Abstract

Ocean warming alters marine population dynamics, yet species differ in their sensitivity to climatic change. We used empirical dynamic modeling (EDM) to quantify causal influences of sea surface temperature (SST) on fish biomass across multiple Atlantic fisheries surveys. Overall, SST causal strength was positively associated with the magnitude of biomass trends, and this relationship strengthened with increasing regional SST trends, indicating widespread coupling between ocean warming and fish population dynamics. Mixed-effects models showed that SST causal strength decreased with species’ thermal preference but increased with habitat depth range, suggesting stronger SST–biomass coupling in colder-water species and those with broader depth ranges. Among biomass-declining populations, 40.8% exhibited significant SST–biomass causal convergence, with cold-water species predominating. Further analysis revealed that species with lower thermal preferences, lower latitudes, and western Atlantic distributions were more likely to experience both biomass declines and significant SST causal effects. Collectively, our results identify ecological and geographic characteristics associated with SST-linked fish biomass declines and provide a broad-scale framework for assessing the vulnerability of marine populations and fisheries to ocean warming.

Abstract

Biotic interactions are recognized as key modulators of heterogeneous range shifts under climate change, yet their influence remains difficult to test across broad spatial scales. Building on invasion ecology, we developed a framework to evaluate how recipient community structure is associated with early occupancy gains within climatically suitable space. We tested predictions from the biotic resistance versus biotic acceptance hypotheses and Darwin's naturalization versus preadaptation hypotheses. Using the Taiwan Breeding Bird Survey (>300 sites; 136 species), we compared Absence-to-Presence (AP) sites, where focal species showed occupancy gain between 2020 and 2021, with Absence-to-Absence (AA) sites where focal species remained undetected despite climatic suitability; sites were paired within species and restricted to locations with plausible propagule access. Across 428 AP–AA pairs spanning 62 species, AP sites showed higher recipient community diversity, supporting biotic acceptance over biotic resistance. Focal species were functionally similar to resident assemblages at AP than AA sites, supporting Darwin's preadaptation hypothesis; phylogenetic distinctiveness showed no effect. Morphology and climate-preference traits drove functional similarity; habitat and foraging traits differentiated more. By adapting invasion hypotheses to climate-related redistribution, our framework provides an empirically testable basis for incorporating recipient community context into predictions of species range dynamics under environmental change.

Abstract

Plastic responses of offspring phenotypes are triggered by their own environments, such as inducible defense (within-generation plasticity), and by environments experienced by prior generations, such as seasonal polyphenism (across-generation plasticity). In phytophagous insects, these contrasting types of phenotypic plasticity should reflect spatio and temporal variations of microhabitat and host-plant quality. Here, we examined phenotypic plasticity of larval feeding traits within and across generations in two sympatric swallowtail butterflies, Papilio memnon and Papilio xuthus, which use the same species of host-plant but depend on different microenvironment. First, we experimentally measured the inducible responses of larval morphology and feeding performance to leaf toughness. Second, we surveyed seasonal variation in egg size and hatchling morphology. Papilio memnon larvae exhibited within-generation plasticity in their head size and mandibles in response to leaf toughness, while P. xuthus did not show such flexibility. In contrast, P. xuthus exhibited across-generation plasticity in egg size and larval morphology correlated to seasonal variation of leaf toughness, while P. memnon did not show significant seasonal variation. Our results suggest that these different types of plasticity in feeding traits are adaptive to spatio and temporal variations in host-plant quality for each species.

Abstract

Cold stress limits tropical ectotherms' northward range expansion. We compared cold tolerance of two tropical gecko species at their northernmost range edge on Amamioshima Island, Japan. Gehyra mutilata colonized the island decades ago, and Hemidactylus frenatus arrived around 2000. We tested whether cold tolerance varies between the established northern population on Okinawa Island and the newer range on Amamioshima. Results showed differences between species. G. mutilata, highly human commensal, had a higher CTmin than H. frenatus. H. frenatus showed little geographic variation in CTmin, while G. mutilata showed none. These findings suggest differences in thermal physiology relate to human commensalism and thermoregulatory behavior, supporting their different invasion histories. The study also offers insights into Bogert's effect on G. mutilata.

Abstract

High-mountain lakes are sensitive indicators of climate shifts and anthropogenic disturbances, yet paleolimnological records remain scarce on subtropical islands. We present a 2500-year high-resolution environmental reconstruction from Cuifeng Lake, Taiwan, using subfossil chironomid assemblages and sediment geochemistry (total nitrogen, TN; total organic carbon, TOC) to examine baseline climate, historical forestry, and exotic fish introductions. Prior to industrial interventions, gradual increases in TN and TOC reflected natural lake infilling. Between AD 65 and 386, increased chironomid density indicated a water-level transgression driven by a warm, humid climate. In the twentieth century, clear-cut logging (1915–1982) inflicted a severe hydrological shock, shifting the chironomid community and expanding filter-feeders from 22.4% to 33.4%. Post-AD 1989, introducing exotic benthivorous fishes triggered a severe multi-trophic regime shift. This biological invasion collapsed chironomid density and caused an unprecedented exponential upsurge in TN and TOC via metabolic excretion and substrate bioturbation. While chironomid communities showed ecological resilience to macro-climatic transitions, historical logging combined with modern biological invasions has locked this alpine system into a permanently altered, non-recoverable state, shifting modern conservation and restoration baselines.

Abstract

Island biogeography predicts that island area governs species richness, yet whether this relationship extends to population-level resilience within species remains poorly understood. Indeed, species-level extinction typically follows a longer process of population loss, making population resilience an urgent conservation target. Testing this requires a species spanning continental and island systems. Sasakia charonda, the national butterfly of Japan and an umbrella species of the Satoyama landscape, provides such a system, with four subspecies spanning continental East Asia, Japan, and Taiwan. Using range-wide sampling and the first chromosome-level reference genome, we integrated phylogenomics, demographic inference, and genotype-environment association to delimit five conservation units (CUs). Two island CUs sharing parallel founder-effect signatures show distinct demographic trajectories, with the larger, more latitudinally extensive island (Japan) maintaining more subpopulations and greater effective population size than the smaller one (Taiwan). A similar pattern appears on the continent, where a highland-restricted lineage with few subpopulations is vulnerable. Habitat area may thus shape demographic resilience through the number of subpopulations a landscape can sustain. The most vulnerable CUs also face the highest projected climate mismatch, compounding their risk. These findings suggest island biogeography principles may extend from species richness to within-species demographic resilience, informing actionable conservation strategies.

Abstract

Rhizocephalans are highly modified and specialized parasites of other crustaceans. Adult rhizocephalan consists of an external reproductive sac (the externa), which is still connected to an internal system of rootlets that ramifies throughout the interior of the host (the interna). These parasites exert control over the host in order to complete their life cycle. We studied the mechanism of host control using an association of the shore crab Metopograpsus thukuhar parasitized by Polyascus planus. First, control over host's reproduction is sex-specific. For females, production of vitellogenin, is not affected, while ovarian maturation is arrested. As for males, production of vitellogenin is induced and testicular maturation hardly affected. Expression of androgenic gland hormone in parasitized males is significantly decreased. Second, the immunity of parasitized hosts is suppressed, with a higher number of hemolymph bacteria, a lower number of circulating hemocytes, and no significant immune responses to tissue-invading rootlets. Necrosis of circulating hemocytes is a key component of the parasite-induced immunosuppression. Finally, an ecdysteroid surge is required to drive the molt cycle, ovarian cycle and secretory cycle of the colleteric gland of sexually mature externa, which collectively influence the reproductive output of (number of larvae released from) the externa.

Abstract

Horsehair worms manipulate insect hosts to enter water, but their effects begin earlier. In Hierodula mantids, infection causes gonadal reduction and alters male wing shape and grooved basiconic antennal sensilla. Artificial infections show that these sex-dependent effects emerge during host sexual differentiation, suggesting interference with male differentiation rather than generalized developmental arrest or juvenilization. The uninfected mantid Amantis nawai provides a natural parallel. Taiwanese males are macropterous or micropterous, whereas females are exclusively micropterous. Macropterous males have more antennal sensilla than micropterous males, whose counts are intermediate between macropterous males and females. This pattern suggests partially shared, sex-dependent regulation. Juvenile hormone (JH) may link these traits. In A. nawai, wing-bud differences appear by the third instar, whereas differences in antennal sensilla appear only in adults. JH declines during the final instar, but micropterous males show a transient mid-instar increase. DZNep treatment during this window preliminarily increased wing length and sensilla number and induced wing-lifting. Although causality and DZNep specificity remain unconfirmed, these results support a two-stage model: early establishment of wing morphs followed by JH-sensitive terminal differentiation of wings and antennae. Natural variation may modify this system in A. nawai, while horsehair worms may disrupt the same developmental module in Hierodula.

Abstract

Hairworms (Nematomorpha) have a two-phase life cycle: larvae infect aquatic benthic invertebrates, which are then eaten by terrestrial insects in which the worms mature. Mature worms drive their hosts into water, a textbook case of the extended phenotype. However, fundamental information on host range and distribution remains scarce in Asia, including Japan.

Focusing on three Japanese species of the genus Chordodes, we compiled host lists from field surveys and conducted infection experiments on definitive hosts. The results indicated that host specificity is set not by the likelihood of encounter but by a physiological filter: whether larvae can establish and develop once ingested.

Furthermore, molecular phylogeographic analysis uncovered distinct patterns of geographic genetic structure for each species. Given that host dispersal drives gene flow in these parasites—which have limited mobility themselves—we had anticipated high levels of gene flow resulting from the combined dispersal capabilities of both aquatic and terrestrial hosts; however, the data actually revealed genetic divergence associated with specific mountain ranges.

In this talk I use host specificity as a lens for reading these patterns, and ask which of the two environments has shaped the distribution of these parasites.

Abstract

Rhizocephalans (Thecostraca: Cirripedia) are parasitic barnacles that infect diverse decapod crustaceans, including hermit crabs, crabs, and shrimps. Peltogasterella gracilis, a parasite of pagurid hermit crabs, exhibits pronounced sexual dimorphism and sex-specific settlement. Female larvae settle on hermit crab hosts, whereas male larvae settle on immature females and subsequently develop into dwarf males. Here, we investigated how these sex-specific settlement patterns are associated with seasonal sex-ratio variation, sex-biased gene expression, and molecular responses during settlement.

Field surveys revealed seasonal variation in offspring sex ratio: male larvae were absent during summer but were produced from autumn to the following spring. This seasonal pattern was suggested to correspond to the availability of unparasitized hosts for female larvae and immature female parasite bodies for male larvae. Comparative transcriptomic analyses of male and female cyprids identified sex-biased genes potentially involved in sex-specific morphology and settlement. Additionally, comparison of gene expression responses to sex-specific settlement substrates revealed distinct molecular responses between male and female cyprids.

These results suggest that seasonal sex allocation and sex-specific molecular mechanisms of settlement are closely linked in P. gracilis, providing a basis for divergent reproductive strategies between male and female larvae.

Abstract

Maternally inherited female-biased sex ratios are found in many arthropods, and one cause is male-killing, in which males die selectively during embryonic or larval development, resulting in all-female broods. In insects, male-killing is mostly caused by bacteria such as Wolbachia, but some symbiotic viruses also induce it.

Homona magnanima (Lepidoptera: Tortricidae) is a major pest of tea plants in East Asia. Segmented double-stranded RNA viruses, Osugoroshi viruses 1–3 (OGV1–3; Partitiviridae), have been identified as the causative agents of male-killing in this species. Unlike bacterial male-killing, which typically occurs during embryogenesis, OGV-induced male death occurs at the larval stage: OGVs are transovarially transmitted and, in young male larvae, cause molting failure and degeneration of the midgut epithelium. Although 27 dsRNA segments—three encoding RNA-dependent RNA polymerases and 24 encoding proteins of unknown function—have been detected in infected hosts, the mechanism by which OGVs kill males remains unknown.

Here, we report the results of omics analyses and analyses of the endocrine system in OGV-infected male larvae, which suggest an endocrine disruption distinct from that involved in bacterial male-killing.

Abstract

Female dinidorid stinkbugs (Hemiptera: Heteroptera: Dinidoridae) possess a distinctive organ on the hind tibiae that has been long interpreted as a ear. In Megymenum gracilicorne, we found that this organ is, in fact, an external symbiotic organ.

This organ have numerous pores connected to secretory cells, from which fungal hyphae reside. During oviposition, the female applies these fungi onto the eggs with "egg-smearing". Subsequently, the hyphae cover the egg mass, providing a physical barrier to protect the parasitoid wasps.

Each female harbor several fungal species, and community composition differed among individuals, localities, and years. This observation suggests the hypothesis that females reacquire fugal symbionts from the environment with each generation.

The fungi are predominantly members of the family Cordycipitaceae, a group consisting of rich entomopathogens, whereas the symbiotic fungi exhibit mild pathogenicity. Consequently, it is plausible that females selectively cultivate less pathogenic fungi within the entomopathogen-relateds.

The mechanisms through which female insects select fungi, and tolerate or avoid infection, remain unclear. However, our findings indicate that other Diniidridae insects also possess analogous organs and exhibit the egg-smearing, whereas Cordycipitaceae dominance appears restricted to Megymenum. Here, we would like to discuss the potential evolutionary history based on what is currently known.

Abstract

In our earlier work, we developed a simple model to describe patterns of parasitism in nature. In this original model, parasite species were randomly seeded within a food web and subsequently transmitted among host species through predator–prey trophic interactions. At the macroscopic level, the model successfully reproduced the observed pattern of parasite diversity across host species. However, at the microscopic level, it was less successful in reproducing the observed parasite diversity of individual host species. In a more recent model, we incorporated additional mechanisms, including competition among parasite species, but these modifications resulted in only limited improvement in explaining patterns of parasitism at the microscopic level. In the present study, we therefore return to the framework of our original model and introduce a slightly more complex transmission mechanism that more realistically represents the biology of parasite complex life cycles. We examine whether incorporating this additional biological realism improves the model's ability to reproduce observed patterns of parasite diversity at both the macroscopic and microscopic levels.

Abstract

Environmental change can alter ecosystem multifunctionality (EMF) by reshaping biological communities, yet ecological frameworks often assume that community–environment and community–function relationships remain constant over time. This assumption overlooks the possibility that shifting selective pressures can modify species' niches and progressively alter these ecological relationships. Here, we investigated how long-term resource stress influences community niche dynamics and their consequences for EMF using a 9-year biweekly time series from a subtropical reservoir. We measured microbial community utilization profiles of 31 carbon substrates, quantifying community niche breadth (NB) as the number of substrates utilized and EMF as the summed utilization rates across all substrates, within moving annual windows. Because carbon utilization was co-limited by phosphorus, resource stress (re-oligotrophication) was quantified via phosphate scarcity, variability, and depletion. Prolonged nutrient stress drove progressive expansion of community-level NB and strengthened its positive relationship with EMF, such that broader NB contributed increasingly to EMF under resource limitation. Consequently, both NB expansion and its enhanced functional contribution jointly elevated EMF over time. Parallel population-level analyses confirmed our predictions at the population level, though with weaker effects, and revealed that community NB broadening arose from two concurrent mechanisms: species turnover and within-population niche plasticity. Our findings demonstrate that environmental change reshapes niches and their functional consequences through multi-level pathways, challenging static assumptions and underscoring the need for dynamic frameworks to predict ecosystem functioning.

Abstract

Understanding how organisms respond to environmental heterogeneity is essential for predicting population persistence under climate change. In salmonids, anadromous and landlocked forms represent alternative life-history strategies, yet how these strategies interact with environmental variation to shape demographic responses remains unclear. We quantified temperature- and density-dependent life-history and demographic variation across a ~21° latitudinal gradient (24–45°N) in masu salmon (Oncorhynchus masou). Environmental heterogeneity generated two major life-history trade-offs: a latitudinal shift in lifetime reproductive allocation between semelparity and iteroparity, and a temperature- and density-dependent trade-off between maturation and survival. These trade-offs produced contrasting demographic responses between migratory forms. Anadromous populations, distributed in colder, high-latitude environments, exhibited stronger environmental regulation, higher net reproductive rates (R₀) under cool conditions, but steeper declines in R₀ with warming. In contrast, landlocked populations showed weaker environmental regulation and relatively stable R₀ across temperature gradients. Our results demonstrate that environmentally mediated energy-allocation trade-offs determine the sensitivity of population growth to warming and highlight the importance of intraspecific life-history diversity for predicting demographic responses to environmental change.

Abstract

Morphological traits scale with body size and vary over time, providing a unique way to track trait variation within animal populations beyond changes in average size. Here we examine whether relationships between body features and body size of an endemic goby change across the population decline and environmental change. We measure 11 morphological features with size in 3,856 individual specimens of the Gymnogobius isaza, collected in 22 years in Lake Biwa. We find that size-dependency in morphological features varied among years, associated with changes in eutrophic conditions, food availability, and fishery and invasion history for potential competitors and predators. After the goby stock decline, pelvic-fin and left pectoral-fin lengths increase less sharply with body size, whereas eye diameter increases more sharply. Moreover, the association between environmental conditions and allometric relationships differed before and after the population decline. Allometric growth across functional traits clearly reorganizes after a severe demographic bottleneck, suggesting plastic allometric responses may themselves evolve adaptively under ecosystem transitions.

Abstract

Plankton stoichiometry (C:N:P ratios in biomass) critically influences the trophic transfer efficiency and secondary production in marine food webs. Nutrient supply and light intensity are key factors affecting phytoplankton stoichiometry. In addition to resource supply, the trophic strategy body of plankton is associated with the values and variability of their stoichiometry: plankton trophic strategy shift from autotrophy to heterotrophy with body size, and stoichiometric variability is lower in heterotrophic zooplankton. In this study, we collected size-fractioned particulate organic matter (POM) and zooplankton and measured the carbon (C), nitrogen (N), and phosphorus (P) contents in different size fractions along the Kuroshio-affected region in the eastern Japan. We investigated (1) the relationship between nitrogenous : phosphorus nutrient concentrations and size-fractioned POM C:N:P ratios, which reflect the stoichiometry of unicellular protists, (2) the relationship between heterotrophy : autotrophic protist ratio and POM C:N:P ratios, (3) the relationship between body size and C:N:P ratios of size-fractioned plankton. Our study reveals that body size is strongly related to the stoichiometry of plankton. Plankton C:N and C:P ratio decreased with body size and heterotrophy, and variation of C:N ratio across sampling sites are smaller in large-size zooplankton. Plankton N:P ratio exhibited a unimodal pattern with body size, possibly reflecting the difference of growth rate of different-sized plankton.

Abstract

Semidiurnal internal tides generated in the Luzon Strait shoal and break on the slope south of the Taiwan Bank, steepening into bores that drive cold-water run-up and generate a turbulent bottom-mixed layer (BML). Successive bores advect this cold, saline, nutrient-rich layer upslope; over the bank it outcrops, depending on the strength of turbulence and the tidal phase, sustaining the recurrent chlorophyll-rich surface water. The physical supply mechanism is well described, but the biological balance is not. Pico- and nanoplankton growth and microzooplankton grazing mortality were measured in the source region south of the tidal mixing front, in the surface layer and in the aphotic zone. Preliminary profiling placed the 1% light depth at 45 m, so the surface samples lie within the euphotic zone and the 60 m bottom-mixed layer below it. We aim to determine whether growth exceeds grazing in the surface layer, to quantify the rate at which pico- and nanophytoplankton abundance declines in the aphotic BML, and to establish the share of that loss attributable to grazing — the terms that determine whether cells transported upslope can seed the surface bloom.

Abstract

In high-latitude regions, studies have highlighted the significance of carbon export through ontogenetic vertical migration by copepods. This process involves accumulating lipids in the surface layer and consuming them during dormancy in the mesopelagic layer. In the subarctic Pacific, lipid storing copepods dominate the zooplankton community, making lipid pump a potentially critical component of carbon sequestration. However, it is difficult to quantify carbon flux through existing observations due to deficiency of data relating their dormancy. To address this gap, we develop a population dynamics model to simulate the life cycle of the dominant copepod Neocalanus plumchrus, incorporating storing lipid dynamics. This model includes eight developmental phases and tracks abundance, structural and lipid weight for each phase, driven by two environmental variables: temperature from the World Ocean Atlas and chlorophyll a concentration from NASA’s Aqua satellite. As the result, the model can reproduce long-term simulations of copepod population dynamics at three stations (Station A7, K2 and Papa). Moreover, it demonstrates regional differences in copepod abundance and carbon export during dormancy. This research could contribute to quantifying the amount of carbon sequestered by copepod species carrying out ontogenetic vertical migration in the subarctic Pacific.

Abstract

Key habitat structures can influence species coexistence, predator avoidance, resource acquisition, and reproductive success. However, previous studies of coral recruitment have largely focused on artificial structures or the effects of natural reef morphology at relatively large spatial scales. In two 8 × 8 m plots in Kāneʻohe Bay, Hawaiʻi, we used Structure-from-Motion photogrammetry to generate high-resolution orthomosaics and digital elevation models, identifying 807 coral recruits and natural reef crevices to examine habitat preferences among coral growth forms. Digitate and corymbose corals occurred more frequently within or near crevices, whereas encrusting and branching corals showed no clear preference. Crevice width was the most important morphological predictor of recruit distribution, followed by maximum depth and circularity, with preferences differing among coral growth forms. By reverse-engineering natural reefs, this study identifies key microhabitat features that promote coral recruitment, providing a pathway for restoration structure design to move beyond iterative trial-and-error toward nature-informed functional design. Our findings also suggest a potential mechanism by which structural complexity may enhance reef recovery: reefs with more abundant and diverse crevices may provide greater availability of suitable settlement habitat and refugia for coral recruits.

Abstract

Growth is a key demographic process shaping population dynamics by regulating reproduction and mortality, with important consequences for the latitudinal structuring of coral assemblages. Although growth in reef-building corals generally declines with increasing latitude, it remains unclear whether this pattern is consistent across taxa and colony sizes. Here, we test the hypothesis that coral growth responses differ between tropical and subtropical-temperate regions, and these differences are both size-dependent and taxon-specific, reflecting differential environmental constraints and life-history strategies. We quantified annual growth rates for 941 colonies spanning a wide size range (planar tissue area, 0.2–1,904 cm²) from five common coral genera (Acropora, Pocillopora, Porites, Dipsastraea, and Favites) across tropical (7 sites, 5°S–9°N) and subtropical–temperate (7 sites, 26–32°N) regions in the western Pacific from 2012 to 2014. For each genus, we applied linear mixed-effects models to evaluate whether growth differed between latitudinal regions and how it varied with colony size. We found pronounced genus- and size-specific growth patterns across latitudinal regions. Pocillopora and Porites grew faster in the tropical region, with differences decreasing as colony size increased. Acropora showed similar trends but high individual variability obscured significant differences. In contrast, Dipsastraea and Favites exhibited faster growth in the tropical region primarily in juvenile size classes. Our findings challenge the assumption of uniform latitudinal declines in coral growth and demonstrate that growth responses across latitudinal regions depend strongly on both taxon and colony size. Incorporating such variability into demographic models will improve predictions of trajectories and tropicalization in coral assemblages under ongoing climate warming.

Abstract

Social insect colonies are spatially heterogeneous, with castes, activities, and resources distributed unevenly across the nest and thereby creating distinct local social environments. Social parasites acquire host-derived resources within these organized societies, yet most previous studies have emphasized parasite traits or associations with particular host individuals or nest locations. How local social environments influence parasite–host interactions and resource acquisition therefore remains an important question. Here, we investigated the termite-associated rove beetle Trichopsenius japonicus, a social parasite of Reticulitermes speratus. Field surveys showed that beetles were concentrated near termite reproductives in natural nests. In preference assays, beetles occupied chambers containing queens more often than those containing kings or additional workers. Behavioural observations further revealed that queen presence increased beetle begging and provisioning by workers. Together, these results indicate that remaining near queens can enhance opportunities for beetles to obtain resources from workers. More broadly, our findings suggest that resource acquisition by social parasites may depend not only on the host individuals involved, but also on the local social context in which parasite–host interactions take place.

Abstract

Body size is a crucial ecological trait, which could be influenced by elevation. The intraspecific responses and mechanisms which are influenced by elevation in termites remain unclear. Mandibles are the most sclerotized and resource-intensive body parts in termites. It is unknown whether mandibles sustain resource allocation during body size changes under limited resources. In this research, we investigated elevational body size trends and mandibular allometry in four widely distributed termite species in Taiwan: Odontotermes formosanus, Glyptotermes satsumensis, Reticulitermes kanmonensis, and Nasutitermes parvonasutus. The results show that not all species exhibited increased body size with elevation. Shifts in colony mean body size were driven by two potential mechanisms: altered individual sizes within the same instar across environments, or changes in colony instar composition despite constant individual instar sizes. In workers and soldiers of all species, mandibles showed significant negative allometry. However, mandibular growth lacked an asymptote, indicating continuous growth relative to other body parts. During this growth, resource allocation is dynamic; sclerotized volume increases, and the bite force moment of different teeth changes accordingly.

Abstract

The ant genus Strumigenys is one of the most diversified ant groups, with nearly 900 described species. Some species have extremely fast trap-jaw that operate on a latch-and-spring mechanism. According to recent molecular phylogeny, this mechanism evolved multiple times among clades distributed across different biogeographic regions. Furthermore, even among these phylogenetically distant species, they exhibit strikingly similar morphologies, suggesting that not only the trap-jaw mechanism but also various related traits have evolved convergently. The most important advantage of the trap-jaw is likely predation, as they are known as predators of agile prey like springtails. Previous studies have suggested that species without a locking mechanism tend to move slowly and have ambush or stalking hunting strategies. In contrast, trap-jaw species with a locking mechanism exhibit more active prey search. However, actual hunting behavior was observed in only a small number of species, and these observations are also phylogenetically biased. To address this knowledge gap, we observed and compared the hunting behavior of trap-jaw Strumigenys species originating from the Oriental and Neotropical regions. As a result, we observed that a few species exhibit extremely passive ambush-hunting behavior previously unknown to trap-jaw species. In addition, we found the species with this ambush-hunting strategy in both Oriental and Neotropical clades.

Abstract

Colony collapse disorder (CCD) of the honey bee, Apis mellifera, is an abnormal phenomenon marked by the sudden loss of most worker bees, including hive bees and foragers, in a colony. Previous studies have shown that exposure to environmental stressors, such as the neonicotinoid pesticide imidacloprid, can trigger early behavioral maturation in hive bees and impair the flight and homing abilities of foragers. These symptoms are closely linked to the rapid collapse of honey bee colonies. The transition from hive tasks to foraging behavior is coordinated with the increasing level of juvenile hormone (JH) III, which plays a crucial role in age polyethism. Elevated levels of JH III in young hive bees can cause early behavioral maturation and result in precocious foraging activity. Despite these insights, the molecular and physiological mechanisms underlying stress-induced precocious forager behavior remain largely unknown, but they may be associated with the level of JH III.

To investigate the molecular and physiological mechanisms underlying sublethal imidacloprid-induced precocious foraging, we used next-generation sequencing (NGS) and gas chromatography-mass spectrometry (GC-MS) to monitor trends in transcriptome profiles and JH III titers in workers of different ages between imidacloprid-treated and control groups. Our initial findings indicate that the transcriptomic profiles of imidacloprid-treated young workers closely resembled those of older control workers, suggesting accelerated behavioral maturation at the molecular level. More frequent sampling from emergence to day 21 revealed age-specific reductions in nurse-associated gene expression and increases in foraging- and JH-associated gene expression. Correspondingly, JH III titers rose earlier in imidacloprid-treated workers, providing physiological evidence consistent with accelerated worker maturation.

The outcome of this project provides genetic and physiological evidence that exposure to sublethal imidacloprid during the larval stage may disrupt the age polyethism in the colony; this could potentially impair individual bee development and threaten colony stability. Our results highlight the need for further research into the long-term ecological impacts of neonicotinoid exposure on honey bee populations.

Abstract

The yellow crazy ant, Anoplolepis gracilipes, is a globally destructive invasive species due to its substantial impacts on biological diversity and ecosystem sustainability. In Taiwan, invasion of A. gracilipes has been associated with declines in land crab populations at several hotspots, and liquid baiting has been implemented since 2018. A better understanding of its biology, behavior and reproduction mode may provide new insights into the development of future pest management strategies. First, a generalized additive model indicated that worker abundance was associated with the human disturbance levels, suggesting that habitat restoration coupled with the removal of human-made objects that may serve as nesting sites for A. gracilipes could discourage its establishment. Moreover, deployment of artificial nests or trapping boxes in areas with high ant activity may facilitate the removal of entire functional colonies. Field studies showed that a single artificial nest successfully removed thousand of workers along with substantial brood and queens from surrounding environments. Second, multidisciplinary approaches revealed that a subset of A. gracilipes workers possess greatly distended gaster and functional ovaries (i.e., physogastric workers). Physogastric workers are an essential worker subcaste as they produce trophic eggs that constitute a major food source for larvae. Therefore, incorporating a low concentration of juvenile hormone analogue as an active ingredient in bait may disrupt the nutrition supply for larvae and subsequently inhibit colony growth. Third, field assay indicated that A. gracilipes workers preferentially retrieved small-size hydrogel beads (outer diameter = 3.1 mm), which could be readily carried by workers and transported directly back to the nest. The deployment of small hydrogel beads may therefore facilitate the efficient transfer of toxicant within the colony while maintaining the palatability of liquid bait over extended periods. Collectively, these findings support an integrated approach to the sustainable management of A. gracilipes.

Abstract

Chronic wind stress is a major physical driver shaping tree interactions. The Stress-Gradient Hypothesis (SGH) predicts that plant interactions shift from competition to facilitation under extreme stress. However, models often assume these interactions are symmetric, leaving the role of functional traits unclear. To investigate this, 5-year tree growth dynamics were analyzed across a continuous, monsoon-driven wind gradient in a subtropical montane cloud forest. Spatial interactions were evaluated using a spatial model and the Neighborhood Competition Index (NCI), incorporating local wind exposure and differences in Specific Leaf Area (SLA) between target trees and neighbors.

A directional shift toward facilitation was observed under high wind exposure, supporting the SGH. Sheltering effects occurred specifically when conservative neighbors (low SLA) buffered resource-acquisitive target trees (high SLA) against wind stress. This physical shielding provided by conservative neighbors mitigates mechanical damage, offsetting the costs of local resource competition. The results demonstrate that the stress gradient hypothesis manifest only if considering the functional strategies between neighbors and target individuals in the forest.

Abstract

Montane cloud forests (MCFs) are rare and fragile ecosystems in Taiwan, strongly shaped by typhoons, monsoons, and frequent fog. This study explores how fog frequency influences functional trait diversity in northern Taiwan’s MCFs. Using 27 transect plots along a fog gradient, we calculated functional richness, dispersion, and evenness using individual-level data for seven plant traits. Linear regressions were used to test the relationships between fog frequency and these diversity indices. Results indicate that foggier sites exhibit significantly higher functional richness and dispersion. However, the relationship between fog frequency and functional evenness is non-significant. As a stressful environmental factor, fog creates cold, humid climate. Surprisingly, instead of homogenizing plant traits, foggier sites show significant functional differentiation. This study offers new ecological interpretations of fog effect on cloud forest vegetation, providing valuable insights for understanding how MCFs function and better understanding how to conserve them.

Abstract

Kin recognition has been documented in numerous plant species; however, its ecological consequences at the community level remain poorly understood. In particular, how kin recognition (genotype discrimination) among neighboring plants influences long-term species coexistence under different dispersal regimes remains unclear. Here, we developed an individual-based simulation model to investigate how kin recognition-mediated cooperation affects biodiversity in spatially structured plant communities.

The model simulated clonal perennial plants on a two-dimensional triangular lattice, where individuals discriminated neighbors based on species identity and pedigree relatedness. Fitness modifications occurred when two related conspecifics interacted with one heterospecific. We compared two cooperation scenarios: a Zero-sum scenario, in which cooperation redistributed fitness without increasing total productivity, and a Tragedy of the Commons (ToC) scenario, in which cooperation generated additional fitness benefits. Both scenarios were examined under local and global dispersal.

Species diversity was consistently higher under local than global dispersal. Local dispersal preserved spatial kin structure, allowing repeated interactions among related individuals and strengthening kin recognition-mediated cooperation. Species persistence increased particularly in the ToC scenario. In contrast, global dispersal disrupted local kin structure and reduced the influence of kin recognition.

Our results demonstrate that the ecological consequences of kin recognition depend on dispersal mode. Kin recognition alone is insufficient to maintain biodiversity; its benefits emerge when restricted dispersal preserves local kin structure. Thus, limited seed dispersal may be a key condition under which kin recognition-mediated cooperation contributes to long-term species coexistence and community stability.

Abstract

How is symbiotic trait variation partitioned across host evolutionary scales? Using a structured block design, we evaluated multi-trait distributions across 1,004 live host plants to quantify how variance is distributed between versus within host species. We tracked functional traits across shoot biomass, root architecture, and symbiotic organ structures (nodules and galls). Using Bayesian mixed-effects models, we calculated model goodness-of-fit and decomposed latent phenotypic variance into host species phylogeny, interspecies variation, intraspecies variation, and experimental block effects. We show that the influence of host evolutionary history varies substantially across trait types: symbiotic organ variation is primarily driven by within-species differences, whereas whole-plant performance metrics are dominated by between-species variation. These results demonstrate how host phylogeny differentially structures phenotypic outcomes in plant-microbe symbioses across macro- and micro-evolutionary scales.

Abstract

In traditional Chinese philosophy, "Earth's Breath" describes the land's vital energy flow. Biologically, this manifests as plant-soil feedbacks driven by cellular oxidative metabolism across the electron transport chains, gradually converting organic matter into mineral nutrients. Unlike the gentle energy flow of decomposition, wildfires represent an unruly oxidation. Traditionally, plants are viewed as passive, while we hypothesized that plants are active holobionts that dynamically guide microbial functions to regulate Earth's Breath. Fire-avoiding pines (Pinus morrisonicola) promote rapid decomposition and robust nitrogen cycling, sustaining their nutrients by continuously flowing with Earth's Breath. In contrast, fire-tolerant pines (P. taiwanensis) may intentionally suppress soil decomposition, effectively holding Earth's Breath to await the massive nutrient release of a post-wildfire reset. We hypothesize pines evolved to either flow with or suppress this energy. Through shotgun metagenomics, we may monitor these underground energetic states, providing cues for building a climate-resilient ecosystem.

Abstract

Flowering phenology is sensitive to human impacts, such as climate change and urbanisation. Numerous studies have examined how urbanised landscapes affect flowering phenology, by comparing along urban–rural gradients. Phenological patterns among microenvironments in the urban ecosystem have received less attention, even though they often offer unique habitats with varying degrees of artificial influence, such as roadsides, drainage ditches, and vacant lots. If microenvironmental differences diversify flowering phenology, the urban matrix might reduce flowering synchrony with neighbouring populations, limiting outcrossing opportunities and therefore reducing reproductive success.

We investigated the flowering phenology and synchrony of the native annual herb Commelina communis in approximately 250 populations at two rural and two urban sites over three years. Our findings revealed that populations in urban sites exhibited earlier flowering onset compared to populations in rural sites. For flowering synchrony, we found that the population in urban sites, growing in drain habitats, and with artificial disturbances, exhibited relatively lower interpopulation flowering synchrony, suggesting their phenology differed from neighbouring populations within the same landscape. These findings highlight the need to consider not only spatial but also temporal fragmentation from diversified flowering phenology when addressing conservation in the urban matrix.

Abstract

Urban expansion has become one of the most pressing global environmental challenges, increasing the need to design biodiversity-friendly cities. However, the complex stakeholder relationships of urban areas make it difficult to be realised. University campuses provide an ideal model system because they represent simplified urban environments that contain both built infrastructure, semi-natural habitats, and high human density. We used university campuses as a microcosm of urban areas to investigate how land cover types influences frog communities. We applied generalized linear mixed models with an information-theoretic model selection framework to examine the associations of frog diversity and land cover types on the campuses. The results show that road coverage consistently received the strongest model support and was negatively associated with frog species richness and several widespread frog species. In contrast, forest, farmland, and water coverage generally exhibited lower support and species-specific effects, indicating that different frog species respond differently to campus land cover composition. Our findings present that university campuses could serve as practical model systems for understanding urban biodiversity. Although amphibian responses to landscape composition are highly species-specific, reducing road impacts should be prioritised in biodiversity-friendly campus planning. These results also provide a scientific basis for extending campus-scale conservation strategies to broader urban planning and green infrastructure design.

Abstract

Roadkill is a major source of wildlife mortality worldwide, and snakes are particularly vulnerable due to their movement behavior and frequent use of roads. However, the influence of landscape structure on snake roadkill remains poorly understood. We examined species-specific associations between landscape structure and roadkill using 13,288 records of 24 snake species collected through a nationwide citizen science project in Taiwan from 2013 to 2017. Generalized linear mixed models were used to evaluate the effects of landscape compositional heterogeneity, configurational heterogeneity, and habitat amount on roadkill counts. Roadkill counts of four species, *Bungarus multicinctus*, *Psammodynastes pulverulentus*, *Oreocryptophis porphyraceus*, and *Elaphe taeniura*, were significantly associated with landscape compositional heterogeneity, whereas configurational heterogeneity showed no significant effects. Regarding habitat amount, roadkill counts of *Naja atra*, *P. pulverulentus*, and *Ptyas mucosa* were significantly negatively associated with forest cover, while *Ptyas major* showed a significant positive association with farmland cover. These results suggest that landscape compositional heterogeneity may be more important than habitat configuration in explaining snake roadkill risk, while habitat effects vary among species. Our findings highlight strong species-specific responses and emphasize the importance of incorporating landscape characteristics into road planning and wildlife mitigation strategies.

Abstract

Plants use airborne volatiles to coordinate defence, yet environmental stress may alter both signal production and how exposed neighbours relay information. Using maize under well-watered, 2-day drought and 5-day drought treatments, we combined PTR-MS and GC-MS with emitter–receiver assays and an empirically constrained spatial simulation. Water limitation changed the strength and composition of indole-rich herbivore-induced plant volatile sources without abolishing induced emission. Receiver-associated indole output varied with the water status of both emitter and receiver plants. In the 5-day trial, the stronger source from well-watered emitters produced lower receiver output than the weaker drought-derived source, whereas 2-day drought receivers responded positively to both sources. In the simulated stand, measured receiver responses extended volatile signal transmission beyond passive transport, and modelled transmission occurred under every tested water-status combination. These findings show that water availability reorganizes airborne defence information at both the emission and receiver stages.

Abstract

Mountain environments in Taiwan and the Japanese Archipelago harbor exceptionally high levels of plant endemism, yet the biogeographic origins of these montane floras remain poorly understood. The two regions differ markedly in latitude, island age, and orogenic history, providing a striking contrast in their natural histories. We therefore expect that their alpine floras have followed distinct histories of assembly and diversification. In this study, we selected several alpine plant lineages distributed predominantly across the Northern Hemisphere and integrated publicly available sequence data with newly generated data to reconstruct their phylogenetic and historical biogeographic patterns. We further applied biogeographic stochastic mapping to reconstruct the potential histories of dispersal, vicariance, and extinction experienced by these lineages in Taiwan, Honshu, and Hokkaido, while accounting for uncertainty in phylogenetic relationships and ancestral range estimation. We then compared temporal changes in these biogeographic processes to investigate how geographic and biological factors have jointly shaped the assembly of alpine floras across these regions. By doing this, our study will help elucidate the biogeographic processes underlying the rich and highly endemic plant diversity of the western Pacific montane islands.

Abstract

Photosymbiosis has evolved independently across multiple animal phyla, yet the cellular principles that repeatedly enabled animals to accommodate photosynthetic symbionts remain unknown. Here we show that the acoel Praesagittifera naikaiensis establishes intercellular photosymbiosis through division of labour among conserved endodermal cell populations rather than the evolution of a specialised symbiont-hosting cell type. Combining single-cell transcriptomics with perturbation of symbiont photosynthesis, we identify an endodermal transcriptional program underlying symbiont maintenance. Lineage-specific genes associated with photosymbiosis are recruited into this endodermal program. Comparative analyses reveal that independently evolved photosymbioses in acoels, corals and sponges converge on the same ancestral endodermal program despite fundamentally distinct cellular architectures and symbiont localisation strategies. Endodermal cells are enriched for evolutionarily ancient metabolic functions and exhibit elevated transcriptional plasticity, suggesting that they provide a conserved cellular context predisposed to regulatory rewiring and symbiont accommodation. Together, our findings suggest that repeated origins of animal photosymbiosis were enabled through recurrent co-option of an ancestral endodermal program coupled with lineage-specific innovations, revealing a general cellular principle underlying the convergent evolution of complex symbioses.

Abstract

Giant clams are iconic bivalves of coral reef ecosystems that harbor photosynthetic symbionts of the family Symbiodiniaceae. Unlike reef-building corals, which maintain their symbionts intracellularly, giant clams host algal cells extracellularly within a tubular system in the outer mantle. However, the molecular mechanisms and evolutionary basis of this unusual photosymbiosis remain poorly understood.

Here, we generated a chromosome-scale genome of the boring giant clam Tridacna crocea and combined comparative genomics with tissue-specific transcriptomics and dark-induced bleaching experiments to identify host genes associated with symbiosis. These analyses revealed several candidate genes potentially involved in nutrient exchange and maintenance of the symbiotic relationship. Among them, genes related to inorganic nitrogen transport may contribute to nutrient supply to the symbiotic algae, while other candidates suggest molecular features shared with intracellular photosymbioses in cnidarians. Comparative and phylogenetic analyses further provided insights into the evolutionary history of these symbiosis-related genes. Together, our results suggest that both conserved and distinctive molecular features may have contributed to the evolution of giant clam photosymbiosis.

Abstract

Photosymbioses are usually viewed as partnerships in which algal symbionts provide photosynthetically fixed carbon to heterotrophic hosts, while hosts provide nutrients and intracellular habitat. Using the ciliate Paramecium bursaria and its green algal symbiont Chlorella variabilis, we investigated how host cellular organization and lipid metabolism contribute to the maintenance of this endosymbiosis. Spatial proteomics of symbiotic and aposymbiotic P. bursaria mapped host proteins across subcellular compartments, identified a candidate perialgal vacuole-associated protein signature, and revealed pronounced remodeling of host lipid droplets during symbiosis. Imaging and pharmacological perturbation showed that lipid droplets accumulate near intracellular algae and that disruption of host lipid metabolism reduces endosymbiont abundance. We then tested whether these remodeled lipid pools participate in metabolic exchange. Lipidomics showed extensive lipid remodeling in both host lipid droplets and endosymbiotic algae. Stable-isotope tracing with host-supplied 13C-oleic acid, combined with NanoSIMS, EA-IRMS, and isotopologue-resolved lipidomics, demonstrated that host-acquired fatty-acid carbon reaches intracellular algae and is incorporated into algal storage and membrane lipids. These results reveal host-to-symbiont organic-carbon transfer and broaden the conventional view of carbon exchange in photosymbiosis.

Abstract

Synchronization with environmental cycles is fundamental for adaptation to rhythmic environments. In a river, water level fluctuations of a 12.4-hour period induced by tidal cycles become more pronounced further downstream. Consequently, biological rhythms may be modified during colonization of non-tidal to tidal habitats. This study analyzed the activity and transcriptomic rhythms in tidal and non-tidal populations of the freshwater snail Semisulcospira reiniana. Under field and laboratory constant conditions, snails in the non-tidal population exhibited diurnal activity patterns, whereas those in the tidal population displayed tidal activity rhythms. The number of genes with tidal rhythmic expression under constant conditions was greater in the tidal population than in the non-tidal population. These results suggest that snails in the tidal population possess biological rhythms with a 12.4-hour period (i.e., circatidal rhythm). The snails were then exposed to simulated tidal cycles to examine the plasticity of their biological rhythms. In both populations, snails exposed to tidal cycles exhibited circatidal activity rhythms and increased tidal rhythmic genes under constant conditions; however, tidal rhythmic genes were more abundant in the tidal populations under comparable conditions. These findings suggest that differences in the rhythms of wild populations result from environmental factors and evolutionary changes during tidal colonization.

Abstract

Starvation is one of the most serious constraint on somatic growth in animals. It can be particularly critical for arthropods with short life cycles. Under food-limited conditions, animals generally reduce investment in growth and development. In contrast, the herbivorous zooplankton Daphnia enlarge the filter screens on their thoracic limbs in response to food shortage. This response is physiologically intriguing because Daphnia invest in the development of their feeding structures despite limited nutrient availability. Our previous ecological research has shown that the degree of filter-screen enlargement differed between clones, suggesting a genetic basis for variation in this morphological plasticity. However, the developmental and cellular mechanisms underlying this morphological response are unclear. Furthermore, the genetic variants causing morphological adaptability between clones have not been identified. The aim of the present study is to elucidate the developmental and cellular mechanisms that regulate the filter-screen enlargement. To this end, cytological observations were initially conducted to determine the developmental stage at which enlargement of the filtering screen occurs. The distribution of cell nuclei in the thoracic limbs was observed using DAPI staining.

Abstract

Diapause enables organisms to survive unfavorable conditions. Although cues such as photoperiod and crowding induce diapause, its propensity varies within species, contributing to adaptation to diverse habitats. However, the molecular basis of this variation remains poorly understood. The water flea Daphnia produces resting eggs as a diapause stage. We investigated the ecological significance and molecular basis of diapause strategies in asexual Daphnia cf. pulex. Field surveys and laboratory experiments revealed that, among two coexisting lineages in the same lake, the lineage with a lower population growth rate rapidly produced resting eggs as competitor density increased. This may allow production of resting eggs before being competitively excluded, suggesting that differences in diapause strategies contribute to their coexistence. To uncover the molecular basis of these differences, we established a comparative system in which resting eggs were consistently induced only in the diapause-prone lineage. Transcriptomic analysis identified genes whose expression changed prior to resting-egg production and implicated juvenile hormone (JH) signaling. Subsequent experiments demonstrated that JH induces resting-egg production and that JH responsiveness differed between lineages with contrasting diapause strategies. Thus, variation in diapause strategies is associated with differences in JH responsiveness. We are currently using genome editing to elucidate this pathway.

Abstract

Conspecific negative density dependence (CNDD) and understory vegetation are important drivers of forest regeneration, yet their combined effects on seedling performance remain poorly understood. We investigated how neighboring tree identity and understory vegetation affect seedling growth and survival in two dominant subtropical rainforest species, in northeastern Taiwan. Seedlings were planted beneath conspecific or heterospecific adult trees with or without understory removal, and a complementary experiment tested the effects of seedling density on performance.

Understory removal consistently enhanced seedling performance. For Engelhardia roxburghiana, removal increased both growth and survival, particularly during the first 400 days, whereas Machilus zuihoensis showed significantly higher survival and a marginal increase in growth. Neighboring tree identity significantly affected seedling survival in both species but had weak effects on growth, with M. zuihoensis surviving better beneath heterospecific than conspecific neighbors during the first 400 days. Seedling density had no significant effect on growth or survival in either species.

Our results indicate that seedling regeneration in the Fushan subtropical forest is jointly shaped by understory vegetation and neighboring tree identity. Contrasting species responses suggest that shade tolerance and mycorrhizal associations may drive species-specific regeneration patterns, underscoring the importance of biotic neighborhood effects for forest management and restoration.

Abstract

Sexual selection varies enormously in strength across animals, yet why certain lineages evolve extraordinary ornaments and displays remains unclear. Strikingly, several of the bird families with the most elaborate plumage and courtship — birds of paradise, cotingas and manakins — are also specialist frugivores, hinting that dietary and mating-system evolution are linked. We tested this connection in manakins (Pipridae), a Neotropical radiation famous for acrobatic lek displays, combining new genome assemblies with functional assays and comparative phylogenetics. All manakin genomes show Z-to-autosome diversity ratios well below the neutral expectation of 0.75, a predicted signature of the strong reproductive skew of lekking, whereas monogamous outgroups do not. Scans for positive selection highlight genes for muscle function, visual perception and dietary physiology, with protein digestion and absorption the only enriched functional category. Two candidates were tested functionally: the umami receptor T1R1–T1R3, which we show acquired sugar sensing at the base of Pipridae through substitutions concentrated in T1R3, and lactase-phlorizin hydrolase, whose glycoside-hydrolysing activity was reduced earlier, in the Tyrannida ancestor. These physiological changes preceded shifts in breeding system and the evolution of dichromatic plumage, suggesting that intensified frugivory set the stage for one of the planet's most colourful and acrobatic avian radiations.

Abstract

Geographic isolation of islands can leave strong signatures in the genomes of both hosts and their parasites. However, host and parasite may experience very different opportunities for dispersal, potentially resulting in contrasting phylogeographic histories. Here, we investigate this question using the Scops Owl species (Otus semitorques and O. lettia) and their ectoparasitic fly, Carnus orientalis, across Japan and Taiwan. We analyzed genome-wide SNPs generated by MIG-seq and mitochondrial COI sequences from Japanese populations of the owl, together with publicly available COI sequences from a closely related Taiwanese population. For C. orientalis, we analyzed COI sequences from Okinawa, Ishikawa, and Sado in Japan and compared them with sequences from Taiwan. Preliminary results indicate strong geographic differentiation in the parasite, with each island forming a genetically distinct group. Phylogenetic relationships of the host and parasite will be compared to assess the degree of geographic and evolutionary concordance between them. We ask whether the parasite has followed the evolutionary history of its host, or whether its distribution reflects independent dispersal and colonization. By comparing these two interacting organisms across the Japan–Taiwan region, this study explores how island geography and host association jointly shape the evolutionary histories of host–parasite systems.

Abstract

Understanding how introduced species establish populations and affect native species is a central issue in invasion biology. Here, we combined whole-genome analyses, demographic inference, hybrid identification, published survey data, and simulations to investigate the introduction history of Zacco platypus in Taiwan and its potential ecological impacts. Genomic data show that Taiwanese Z. platypus comprise two distinct genomic clusters associated with the Keelung and Xindian rivers. Demographic analyses supported independent introductions of the two populations, each founded by a small number of individuals and followed by rapid population expansion. Genome-wide analyses further confirmed F1 hybridization between Z. platypus and three native Opsariichthyini species. Hybridization with Opsariichthys evolans was strongly asymmetric, with native females serving as the maternal parent in most hybrids, suggesting reproductive costs on native populations. Simulation showed that asymmetric hybridization alone could generate a progressive decline in O. evolans and, under some simulated scenarios, ultimately lead to its replacement by Z. platypus. Consistent with this prediction published survey data revealed declines in the relative abundance of O. evolans in both rivers. Together, our findings reveal multiple independent introductions of Z. platypus in Taiwan and suggest that asymmetric reproductive interference may represent an important mechanism affecting native fish populations.

Abstract

How much individuals invest in cooperation in animal societies usually remains conditional on the environment, yet why populations differ in this conditionality is largely unknown. We combine a common garden experiment, field manipulations and theoretical modeling to ask whether two populations of the burying beetle Nicrophorus nepalensis diverge in these response rules. In the common garden, offspring from Mt. Hehuan in Taiwan responded more strongly to both blowflies and warming, whereas those from Mt. Jiajin in China showed a much smaller blowfly-induced increase and a weaker temperature response. The populations therefore differ in the conditionality of cooperation rather than in how cooperative they are. In the field, the advantage of groups over pairs increased with temperature at Mt. Hehuan but was confined to the cold end at Mt. Jiajin. That cold end is also where the congener competitor N. schawalleri occurs, absent from Mt. Hehuan. Adding this congener to groups reduced investment and breeding success, indicating that benefits generated by cooperation are hard to retain. The favored rule thus depends on what a cue predicts about the loss cooperation can recover and retain, making cooperative conditionality a distinct axis of social evolution shaped by competitor communities.

Abstract

Animals use personal and social information when deciding where to feed, reproduce, and rest, but these information sources may conflict. We tested whether social information outweighs resource quality during roost selection in *Thyroptera tricolor*, a social bat that roosts in ephemeral furled leaves. Flying bats were given a choice between an unoccupied high-quality roost and a low-quality roost occupied by a social group member, with social information conveyed through contact calls. We recorded roost choice, entry latency, and response-call timing. Without social information, bats showed no clear preference between roost types. However, when response calls came from the occupied low-quality roost, bats were approximately 40 times more likely to select it despite the availability of a higher-quality alternative. Bats also entered roosts faster when occupants responded quickly, indicating that social cues influenced both choice and decision speed. These findings demonstrate that *T. tricolor* prioritizes social information over resource quality when the two conflict. The benefits of maintaining social cohesion may therefore outweigh the immediate advantages of selecting the highest-quality resource, highlighting how animals integrate competing information sources under ecological uncertainty.

Abstract

Behavioral lateralization has been documented in various animal species and has been proposed as a potential indicator of physiological state and animal welfare. However, evidence for stress-related effects on lateralization in reptiles remains limited. We investigated behavioral lateralization in relation to stress-related behavioral contexts and body condition in twelve Northern snake-necked turtles (𝘊𝘩𝘦𝘭𝘰𝘥𝘪𝘯𝘢 𝘳𝘶𝘨𝘰𝘴𝘢), a species characterized by asymmetric neck bending. Four behavioral assays were conducted: resting posture and feeding handedness represented non-stress contexts, whereas stimulation response and righting reflex represented acute stress-related contexts. Only one individual exhibited significant lateralization, showing a left-biased neck-bending response during the stimulation assay. No significant population-level lateralization was detected in any behavioral assay, although resting behavior showed a marginal trend toward right-biased lateralization. However, lateralization strength was significantly influenced by an interaction between body condition and behavioral context. Low-condition individuals exhibited stronger lateralization under acute stress-related contexts than those in high body condition, and stronger lateralization during stress-related than non-stress behaviors. These findings suggest that behavioral lateralization is generally weak in study turtles, but its expression may vary with body condition and behavioral context. Our results suggest that behavioral lateralization may have potential as a non-invasive indicator of individual physiological condition in reptiles.

Keywords: behavioral lateralization; body condition; handedness; reptiles; stress

Abstract

Traditionally, abiotic drivers and predator–prey interactions have been considered critical to shaping the species composition of a marine zooplankton community, whereas the role of indirect biotic processes, such as exploitative competition, remains unexamined. The competitive performance of a zooplankton can be limited by biochemical mismatches between its requirements and available prey, known as stoichiometric imbalance. Such imbalance impairs zooplankton growth and reproduction, thereby reducing their competitiveness. Stoichiometric imbalance is known to shape zooplankton communities in freshwater systems; however, its role in marine systems has largely been examined only at species or individual level under experimental conditions. To fill the gap, we measured family-level taxonomic composition and carbon, nitrogen, and phosphorus ratios (C:N:P) of herbivorous zooplankton and their stoichiometric imbalance with prey in the southern East China Sea. Our results showed zooplankton stoichiometry was stable within but variable among families. Family-level relative abundance was significantly associated to phosphorus imbalance. Despite seasonal shifts in dominant families, the imbalance–relative abundance relationship remained consistent, suggesting that stoichiometric imbalance is an important factor contributing to which families can dominate. Notably, phosphorus excess did not negatively affect relative abundance, a pattern that contrasts with the traditional stoichiometric knife-edge hypothesis.

Abstract

Nanoplankton encompass autotrophic, mixotrophic, and heterotrophic taxa that occupy distinct ecological roles in marine food webs, yet how these trophic groups are distributed across environmental gradients remains poorly understood. This study quantified their abundances and evaluated their relationships with environmental gradients in the southern East China Sea. Trophic groups were characterized using a double-staining protocol and a CytoSense flow cytometer. Principal component analysis (PCA) revealed distinct horizontal (shelf – offshore) and vertical sample distributions driven by environmental parameters and nanoplankton abundances. Mixotrophic nanoplankton abundance was marginally correlated with salinity and temperature, consistent with previous studies showing that their distribution is governed by water masses. Heterotrophic nanoplankton abundance was negatively correlated with relative mixed-layer depth (Z / Z_MLD). In contrast, expected environmental drivers, including light availability for autotrophs, showed no significant correlation with the abundance of individual trophic groups, suggesting that strong vertical mixing may weaken the coupling between trophic group distributions and conventional environmental controls, such as light limitation. These findings provide empirical insight into nanoplankton trophic dynamics under well-mixed hydrodynamic conditions.

Abstract

Many studies have shown that microbial food webs dominate more than 70% of carbon cycling in the ocean, particularly through the trophic interactions among pico- and nano-sized plankton. Trophic interactions among pico- and nanoplankton are commonly inferred from their isotopic signatures. However, the complex trophic relationship may blur such isotopic signatures. The objective of this study is to assess this potential mismatch by confronting the empirically measured isotopic signatures and trophic interactions.

In this study, dilution experiments were conducted to estimate isotopic signatures as the growth rates and grazing mortality of pico- and nanoplankton. Size-fractionated filtration was used to separate pico- and nano-sized particulate organic matter (POM) for measuring carbon and nitrogen stable isotope signature (δ¹³C and δ¹⁵N). We have conducted dilution experiments and isotope sampling across marine environments including rocky coast, estuarine, and open ocean. The ultimate goal of this study is to establish a relationship between trophic interactions and carbon and nitrogen stable isotope signatures across different water masses and to provide new insights into grazing dynamics within estuarine and marine microbial food webs.

Abstract

This study investigates how nanoflagellate grazing and viral lysis influence dissolved organic carbon (DOC) quantity and bioavailability in coastal waters.

Modified dilution experiments were conducted using seawater collected from ChaoJin, Taiwan.<0.2 μm and <30 kDa seawater filtrates were used for grazing and viral dilution series, respectively. DOC measurements and subsequent dark incubations assessed changes in DOC quantity and bioavailability.

The viral dilution series generally showed higher DOC concentration-ratio and lability responses than the grazing series.

These patterns suggest that viral processes may contribute to changes in DOC quantity and bioavailability. Further microbial mortality measurements and filtration controls are needed to clarify their contribution relative to grazing.

Abstract

Picoplankton refers to the portion of plankton with cell sizes between 0.2 and 2 micrometers, accounting for approximately half of primary productivity on average. Picoplankton die in two ways: first, through predation, which accounts for 30% to 70% of grazing mortality; second, through viral lysis. Viral lysis can lead to mortality rates of 10% to 50%, thus it can be considered a major cause of bacterial death, and in some cases, its impact can rival that of predation-induced mortality. Therefore, this study aims to explore the seasonal proportional relationship between predation and lysis。I compared the grazing mortality rate and viral lysis rate data from March to August. The results showed that the closer the season progressed toward summer, the higher the net growth rate of heterotrophic bacteria and the higher the mortality rate, but the viral lysis rate did not change much and even showed a slight downward trend.

Abstract

Genomic evidence suggests uncultivated Candidatus Poseidoniales (MGII archaea) rely on algal-derived organic matter, yet in situ standing stocks correlate with ambient nutrients and lag behind primary production. However, compositional biases, shifts in water masses, and the lack of direct carbon flux measurements have obscured the magnitude and timing of MGII responses to environmental change. Here, we tracked a water mass during a 7-day high-frequency Lagrangian cruise in the southern East China Sea, with sampling conducted every 6 h, and quantified MGIIa and MGIIb absolute abundances using amplicon sequencing with an internal genomic DNA spike-in. We found that absolute MGII abundance did not spatially align with peak phytoplankton biomass at the Deep Chlorophyll Maximum (DCM), contrary to the expectation that MGII archaea closely track phytoplankton biomass. Notably, a transient surface nutrient pulse observed during the time series was followed by a surge in absolute MGII standing stocks 6 hours later, capturing a discrete in situ response lag and demonstrating their capacity for rapid population expansion following transient perturbations. In summary, this suggests that MGII populations may not respond immediately after an environmental pulse but instead exhibit a multi-hour delay.

Abstract

Microbial plankton dynamics in shallow coastal lagoons are regulated by bottom-up resource availability and top-down grazing, while their relative importance may shift rapidly under environmental variability and disturbance. We conducted a 21-day high-frequency field study in Chi-gu Lagoon, a shallow oyster-farming lagoon in southwestern Taiwan, to investigate how microbial plankton regulation varies through time and responds to episodic environmental disturbance. At a focal oyster-farming site, paired day and night sampling was conducted throughout the study, with replicated dilution experiments used to assess phytoplankton growth and grazing mortality. Additional sampling at sites with contrasting oyster-farming intensity provided a spatial comparison on selected occasions. The study period also encompassed a typhoon and heavy rainfall, enabling observations across pre-disturbance, disturbance, and recovery phases. Biological sampling was accompanied by measurements of nutrients and microbial community composition, while temperature, salinity, and turbidity were recorded continuously at one-minute intervals. This integrated design provides a framework for examining short-term variability in bottom-up and top-down regulation and how microbial food-web processes respond to environmental disturbance in a highly dynamic coastal ecosystem.

Abstract

Body size is a fundamental trait that structures aquatic food webs by determining predator-prey mass ratios (PPMR). In simple, size-structured ecosystems, trophic position (TP) increases linearly with body size. However, empirical studies reveal that size-TP relationships frequently deviate from linearity, creating non-linear structure. This leads to the research questions: “What are the seasonal patterns in the size-based trophic position relationship?” and “How do environmental changes influence the size-based trophic position relationship in aquatic ecosystems?”. This study aims to investigate seasonal patterns of size-trophic position relationships of the planktonic food web across contrasting mixing regimes in subtropical Feitsui Reservoir. Carbon (δ^13 C)and nitrogen (δ^15 N) stable isotope ratios were analysed to estimate the TP of each size fraction relative to basal sources. Size-TP relationships were evaluated using linear regression. Preliminary results demonstrate that while the overall size-TP relationship was positive across the year, it was statistically significant and steepest exclusively during winter. During spring, summer and autumn, the relationship became non-significant, with points scattering away from the linear regression model. These findings suggest that seasonal hydrographic mixing may affect the linearity of energy transfer pathways in subtropical freshwater ecosystems.

Abstract

Enclosed aquatic systems are often metabolically autotrophic and act as carbon sinks, with primary production generally greater than or equal to community respiration. However, terrestrial inputs introduce allochthonous organic carbon that support microbial respiration, potentially shifting the system toward a heterotrophic state and net carbon release. Because extreme weather can alter the allochthonous inputs from terrestrial systems, its effects on the balance between carbon emissions and sequestration in aquatic systems through changes in terrestrial inputs required further evaluation. To address this issue, we combined a soil-addition experiment with in situ measurements of community respiration to assess how respiration rates respond to soil addition under different environmental conditions. Field measurements showed that respiration rates were significantly lower after extreme rainfall events than before the events at depths of 2 and 10 m (p = 0.01 and p = 0.03, respectively), whereas no significant difference was observed at 20 m. In the soil-addition experiment, respiration rates gradually increased over 48h. These findings suggest that terrestrial inputs likely affect the metabolic status of aquatic systems, especially following extreme rainfall events.

Abstract

A fish population with highly aggregated spatial distribution (i.e., high spatial variability in biomass) can have reduced population resilience and recovery potential following environmental disturbances. Although drivers influencing fish population spatial variability have been a research focus, clear causal linkages remain limited. In particular, bottom-up (i.e., abundance, composition, and spatial variation of prey) effects on spatial variability of marine predatory fishes have not been carefully examined. Using 34-year fish survey data from the North Sea, we applied empirical dynamic modeling (EDM) to quantify the effects of population dynamics (i.e., abundance and age structure of the target population), environmental factors, prey fields (i.e., total abundance, spatial variability, and taxonomic compositions of prey), and fishing on spatial variability of each target fish population. Analyzing six fish populations where data are sufficient, we found that prey beta-diversity exerted positive causal influences on predator (whiting and plaice) spatial variability, suggesting prey-selective feeding behavior shapes fish distributions as prey composition shifts in space. In contrast, high abundance or diverse age structure of fish helps reduce population spatial variability in five species. The causal impacts of temperature and climate indices varied among species in both direction and magnitude, whereas effects of annual fishing mortality were scarcely detected as a causal variable for spatial variability of the target population. Our findings underscore the importance of incorporating spatially explicit drivers into fisheries management.

Abstract

Climate-related environmental change can restructure communities by driving non-random species gains and losses, thereby generating directional shifts in community structure. However, the temporal dynamics of marine fish communities and their association with environmental changes remain poorly understood. In this study, we used environmental and fish community data from the North Sea (1999 –2025) and quantified functional structure using standardized effect sizes of mean pairwise functional distance (SES.MFD) and mean nearest-neighbour functional distance (SES.MNFD), and phylogenetic structure using mean pairwise phylogenetic distance (SES.MPD) and mean nearest-taxon distance (SES.MNTD). Our results showed greater temporal environmental variability and greater changes in community structure in the southern than northern North Sea. In the south, SES.MFD increased after 2015 in Q1, SES.MPD increased in Q1 but decreased in Q3, and SES.MNTD increased after 2012 in Q1. These changes were correlated with nutrient, primary production, and salinity. In contrast, the north showed only decreasing SES.MNFD and SES.MNTD in Q3, correlated with nitrate and salinity. Overall, temporal changes of North Sea fish community were spatially and seasonally heterogeneous, with stronger changes in the more environmentally variable southern region.

Abstract

Fish larval traits, like size when settling in juvenile habitat (settlement size) and time spent before settlement (pelagic larval duration, PLD), are temperature-sensitive and influence juvenile survival and dispersal. Although warming and fluctuating temperatures are known to impact fish size, impacts on larval stage remain poorly understood. We examine how temperature affects these larval traits and the possible pathway in the thermally dynamic intertidal zone. 2604 fish representing 10 species, with individual-based temperature anomaly and variability, representing whether larvae experience higher/lower and more/less fluctuation in mean daily temperature compared to species means, were sampled across Japan and Taiwan. Mixed-effects models reveal that neither temperature anomaly nor variability directly affects settlement size. However, per 1 °C² increase in temperature variability, PLD lengthens by 1.96%, and per 1% increase in PLD, settlement size increases by 0.44%, indicating an indirect pathway from temperature variability to settlement size through PLD. Species-specific PLD responses to temperature variability ranged from 0.33% to 3.49% per 1 °C² increase, and these species-specific slopes were positively correlated with median tidepool depth distribution, indicating stronger PLD responses among deeper-water-associated species. Under anticipated more fluctuating temperatures under warming, subtidal fish larvae may be particularly affected.

Abstract

Habitat mapping is essential for characterizing ecological patterns, yet ground truth annotations aren’t always available because they require time and expertise. Foundation models enable semantic representation learning to extract meaningful features for habitat mapping, yet their potential in low-visibility benthic environments remains under-explored. We collected spatial, visual, and acoustic data during a one-day snorkeling transect survey in Nakijin, Okinawa, Japan, across a substrate mosaic of sand, rock, and branching coral. A Gaussian mixture model was trained on DINOv2 representations and validated against expert annotations in a sand/branching-coral sub-area. Classification achieved a ROC-AUC score of 0.9886. Qualitative analysis of the full transect showed the representation meaningfully captured complex, multi-substrate mosaics beyond the validated sub-area. We further derived eco-acoustic indicators, including snapping shrimp intensity and fish call abundance, which could link acoustic activity to substrate type in further studies. These findings demonstrate the practical value of foundation-model representation learning for scalable benthic habitat mapping, with promising extensibility to other complex habitats. Future work will explore multi-modal integration, fusing visual and acoustic representations across multiple foundation models.

Abstract

Coral mass spawning is an annual event in which numerous colonies release gametes with precise synchrony. As most reef-building corals spawn only once a year, the timing of gamete release is critical for maximizing fertilization. Recent studies demonstrated that moonlight suppresses spawning, and that the dark period between sunset and moonrise serves as a spawning cue. However, the mechanisms underlying this regulation remain poorly understood. In this study, we investigated the effect of the dark cue on gametogenesis and gene expression in the coral Galaxea fascicularis. Coral fragments were maintained in tanks with and without cue, and samples were collected daily until spawning occurred. Histological and transcriptomic analyses were performed to examine changes in gonadal development and molecular pathways associated with the cue. Under dark condition, all colonies spawned synchronously, whereas no spawning occurred in the control under artificial moonlight. Our results show that the dark cue regulates critical stages of gametogenesis, enabling progression toward gamete maturation and spawning. Transcriptomic analysis further revealed sets of genes responsive to the cue, including both common and sex-specific patterns of regulation. Together, these findings provide new insights into the molecular and cellular basis of how environmental cues, particularly lunar cycles, regulate coral reproduction.

Abstract

Many broadcast-spawning corals release gametes within a narrow window after sunset. Spawning synchrony is essential for reproduction success, but whether this timing is determined by sunset alone or is also regulated by an endogenous clock remains unclear. We investigated how altered sunset timing affected reproductive events in the merulinid coral Dipsastraea speciosa. Here we show that advancing sunset by 2 h induced earlier germinal vesicle breakdown (GVBD), egg-sperm bundle formation, and spawning. In contrast, delaying sunset by 2 h or maintaining constant light did not alter the timing of these events, which occurred at the same clock times as in the control. Moreover, preliminary RNA-seq analysis suggested that some gene expression patterns also shifted earlier under advanced sunset. Together, these findings suggest that sunset acts as a cue for the timing of coral spawning. However, spawning did not occur later when sunset was delayed, suggesting that an endogenous clock may also regulate its timing. Further analysis of the RNA-seq data may provide molecular evidence for this possibility.

Abstract

Bleaching opens the possibility for corals to get new symbiotic partners.

Corals host algal symbionts of the family Symbiodiniaceae and rely on their photosynthesis for survival and growth. When corals are exposed to environmental stress such as rising seawater temperatures, they lose their symbionts and bleach. However, bleached corals are still alive, and some can recover if they can repopulate the algal symbionts. Previous studies have reported the changes in symbiont composition before and after bleaching, and thermotolerant symbionts have been found in corals that have recovered from bleaching. Although these observations suggest that bleaching occurs to obtain new algal symbionts suitable for changing environments, it has not been investigated yet. To examine whether bleaching enhances the acquisition of new algal symbionts, we conducted experiments using the model organism sea anemone Exaiptasia. We inoculated algal symbionts into both healthy (control) and bleached hosts, and found that bleached hosts acquired more algal symbionts than controls. Our findings suggest that the expulsion of resident symbionts promotes the uptake of new symbionts. In short, bleaching is a double-edged sword: it acts as an environmental adaptation, but it also leads to starvation.

Abstract

Parasitic crustaceans can modify host sexual traits, but the extent to which these effects vary among host–parasite combinations remains poorly understood. Rhizocephalan barnacles and bopyrid isopods offer opportunities to examine such morphological alterations in decapod hosts. Here, we quantitatively compared morphological feminization associated with rhizocephalan parasitism in hermit crabs of the genus Pagurus. Specimens collected at multiple Japanese localities between 2018 and 2025 were classified as unparasitized females, unparasitized males, or parasitized males. We assessed the presence of female-type pleopods and measured shield and cheliped lengths to evaluate changes in secondary sexual characteristics. Parasitized males showed increased frequencies of female-type pleopods in several host–parasite combinations. Cheliped shortening was also evident in some combinations, with effect size analyses indicating that relative cheliped lengths approached those of unparasitized females. In other combinations, this convergence toward female morphology was not observed. These findings demonstrate that the morphological traits affected and the degree of feminization vary among host–parasite combinations. Comparative analyses across parasitic crustaceans and their hosts may help clarify the diversity of host phenotypic modification and provide a basis for investigating its underlying mechanisms.

Abstract

Parasite spillover occurs when invasive hosts transmit their parasites to native hosts, while spillback arises when invasive hosts acquire native parasites and subsequently amplify their transmission. Both processes can reshape host–parasite dynamics and affect ecosystem health. In Taiwan, the African Sacred Ibis (Threskiornis aethiopicus), a long-established invasive waterbird, has the potential to introduce non-native parasites or alter the transmission of local parasites, yet empirical evidence remains limited. This study investigated parasitic infections in African Sacred Ibises and native herons inhabiting Taiwanese coastal wetlands, using morphological and molecular approaches to assess potential spillover and spillback events. Two major helminth parasites were identified in the African Sacred Ibis populations: an acanthocephalan (Southwellina hispida) and a trematode (Patagifer sp.). Comparative analyses with parasites from native herons suggest that S. hispida, a generalist infecting multiple waterbird species, represents a likely case of spillback, whereas Patagifer sp., which exhibit host specificity, may indicate potential spillover. These findings provide new insights into parasite exchange between invasive and native waterbirds and underscore the broader ecological implications of host–parasite interactions in invasion biology.

Abstract

Mosquito–environment dynamics are often nonlinear, with the direction and strength of environmental effects varying with system state. Linear models with fixed parameters may inadequately capture these relationships, limiting our understanding of population fluctuations. We integrated weekly ovitrap egg counts and meteorological data from Tainan, Taiwan, within 2 km hexagonal grids. MDR S-map models were fitted separately to each grid to estimate time-varying coefficients for environmental variables at different time lags. Relationships between mean coefficients and urbanization intensity were also examined across grids. Current-week temperature, precipitation lagged by two weeks, and relative humidity lagged by two weeks showed positive associations with egg counts, whereas precipitation lagged by one week and wind speed showed negative associations. With increasing urbanization, the coefficients for precipitation lagged by one week tended to become more negative, while those for precipitation lagged by two weeks tended to become more positive. These patterns suggest that urbanization may be associated with differences in mosquito responses to precipitation. By examining time-varying coefficients, this study characterizes mosquito–environment relationships across temporal lags and land-use contexts, contributing to a dynamical understanding of mosquito population fluctuations and informing mosquito monitoring and control.

Abstract

Mosquito populations respond to environmental conditions through complex nonlinear relationships that are difficult to characterize using conventional linear approaches. This study applies Empirical Dynamic Modeling (EDM) to predict mosquito activity in Tainan, Taiwan. Weekly ovitrap egg counts and meteorological data were integrated into grid-based time series for analysis. We applied Sequential Locally Weighted Global Linear Maps (S-Map) and Gaussian Process Empirical Dynamic Modeling (GPEDM) to evaluate predictive performance and uncertainty. S-Map achieved a mean correlation of 0.770 between predictions and observations across the study grids, capturing variation in mosquito activity. GPEDM achieved a mean correlation of 0.640, with predictive intervals containing 92.23% of observations with valid predictions. These findings demonstrate the potential of nonlinear dynamical methods for mosquito prediction. Combining predictive estimates with uncertainty information may inform mosquito surveillance planning and vector management.

Abstract

Population abundance of Aedes albopictus is an important indicator of the potential risk of mosquito-borne diseases, but its distribution and abundance may vary among habitat types and elevations because of differences in local environmental conditions. To better understand the ecological mechanisms underlying variation in mosquito abundance, we conducted a systematic survey across different habitat types and elevations and evaluated the hypothesized direct and indirect relationships among environmental variables. We surveyed mosquitoes, potential mosquito predators, and water quality across three habitat types and three elevations in northern Taiwan. Mosquitoes were sampled monthly for one year using three sampling methods. A total of 4,667 Ae. albopictus individuals were collected, and 238 potential mosquito predators were recorded. Ae. albopictus was consistently more abundant in anthropogenic habitats across all three elevations. Furthermore, elevation and habitat type were associated with local temperature and water turbidity, which were in turn related to mosquito abundance and the occurrence of potential predators. Our results demonstrate that habitat characteristics can influence Ae. albopictus populations through both direct and indirect ecological pathways, highlighting the importance of considering local environmental context when assessing spatial variation in mosquito abundance.

Abstract

Human-dominated landscapes, including agricultural and aquaculture landscapes, are often considered to have limited value for wildlife conservation. However, growing evidence suggests that these landscapes can support biodiversity and provide important ecosystem functions. Their role in conserving migratory species remains poorly understood. Using data from the Taiwan New Year Bird Count, we examined associations between wintering bird diversity and land-use types across different regions of Taiwan. Generalized linear mixed models revealed that northern and southwestern Taiwan supported higher wintering bird richness, with aquaculture landscapes exhibiting particularly high diversity. Agricultural landscapes were positively associated with the occurrence of 4 wintering waterbird species, 6 landbird species, and 1 raptor species, while aquaculture landscapes, particularly in southwestern Taiwan, were associated with 13 wintering waterbird species. These findings demonstrate that human-dominated production landscapes can provide valuable habitats for migratory birds and different production landscapes can support distinct assemblages of species. As natural habitats continue to decline worldwide, promoting biodiversity-friendly management of agricultural and aquaculture landscapes could help compensate for habitat loss and enhance the conservation of migratory birds.

Abstract

This study investigated the impacts of forest monoculture on the temporal co-existence mechanisms of medium-to-large mammalian communities. Camera trap monitoring was conducted during the autumn and winter seasons of 2025–2026 across three natural forest sites and one plantation forest site. Species relative abundance was evaluated using the Occurrence Index (OI). Daily activity rhythms were quantified via Kernel Density Estimation, and temporal co-existence strategies were analyzed using the overlap coefficient. Our results indicated that the Formosan reeve's muntjac ( Muntiacus reevesi micrurus ) maintained an absolute numerical dominance across all habitat types. However, spatial community analysis revealed severe behavioral restriction and localized clustering within the plantation forest, driving a significant increase in the spatial turnover rate (~0.55) during winter. Regarding temporal partitioning, species-pair overlap analysis demonstrated that sympatric herbivores and carnivores effectively achieved coexistence through microhabitat selection in natural forests. Conversely, within the structurally simplified and resource-limited plantation forest, several species exhibited significant temporal phase shifts, modifying their typical diurnal or crepuscular rhythms to achieve temporal avoidance. This study quantifies how plantation monocultures alter the spatio-temporal utilization strategies of mammalian communities. These findings provide critical baseline data for future ecological restoration and habitat management of plantation forests.

Keywords: Camera trapping, Forest monoculture, Activity rhythm, Temporal overlap, Muntiacus reevesi micrurus

Abstract

The yellow pond turtle (Mauremys mutica), a species native to Taiwan, is listed as Endangered (EN) by the IUCN and is designated as an Endangered Species of Protected Wildlife in Taiwan. Beyond protected, low-disturbance habitats, little is known about whether agricultural wetlands on the urban fringe can support the persistence of its populations. In this study, we compared two sites with sharply contrasting levels of anthropogenic disturbance. Urban farmland in Shulin District, New Taipei City, represents a highly disturbed site, where high densities of the invasive red-eared slider (Trachemys scripta elegans) co-occur with the native Chinese stripe-necked turtle (Mauremys sinensis), which poses a risk of hybridization. In contrast, the aquatic pond at Fushan Botanical Garden, Yilan, represents a low-disturbance site that is free of invasive species and provides a complete habitat meeting the needs of the species’ entire life history. Turtles were live-captured using cylindrical fish traps and individually marked by marginal scute notching. A total of 98 individuals were recorded (47 at Shulin and 51 at Fushan). Six morphological traits were measured, body condition was assessed using the residuals of a linear regression of body mass on straight carapace length, and monthly variation in captures was expressed as catch per unit effort (CPUE). Population structure differed significantly between the two sites: the Shulin site had a higher proportion of juveniles (30/47), and its adults were predominantly female (14 females, 3 males), whereas the Fushan site was significantly dominated by adults (42/51) and had a higher proportion of males (30 males, 12 females). Morphologically, males showed no significant differences in any trait between the two sites. Females at Fushan were significantly larger only in shell height; however, Shulin females exhibited significantly greater individual variation in five morphological traits, including carapace and plastron measurements, as well as in body mass. Body condition of adults did not differ significantly between the two sites, although Fushan females showed significantly greater individual variation. Captures at both sites peaked in spring and summer and dropped to their lowest levels in autumn and winter, indicating seasonality in capture rates. Our current results suggest that urban farmland may have the potential to support local reproduction and maintain a stable population of M. mutica, as the interconnected network of irrigation ditches may simultaneously provide corridors for dispersal, refuges for juveniles, and alternative food sources. In addition, we speculate that the significant difference in sex ratio between the two sites may be related to the influence of environmental temperature on sex determination; however, the exact mechanism requires confirmation with more comprehensive microhabitat temperature and population data in the future. We recommend that future conservation strategies encourage the incorporation of wildlife-friendly agricultural landscapes into ecological networks in lowland hills and urban fringes as other effective area-based conservation measures (OECMs), and the establishment of urban blue-green infrastructure, so as to create favorable habitats for the yellow pond turtle.

Keywords: yellow pond turtle; population structure; morphological comparison; urban blue-green infrastructure

Abstract

Sound source localization is an emerging technique in ecoacoustics for investigating population dynamics and individual movement tracking. This approach relies on bearing angle estimation of sound sources. However, noise interference severely affects the robustness of estimation, particularly in complex soundscapes such as tropical forests characterized by abundant ambient noise. To address this issue, we propose using source separation to reduce noise interference and thereby enhance the robustness of spatial localization across multiple channels. In this study, we computed the time difference of arrival (TDOA) of acoustic events from multi-channel recordings of a sika deer (Cervus nippon taiouanus) population in an uplifted coral reef nature reserve, where insect sounds served as intense biophonic noise affecting TDOA estimation of the target signal. Two denoising treatments were compared: the Butterworth filter as a traditional method, and the source separation method provided by soundscape_IR. Results showed that TDOA estimation under source separation produced more continuous and convergent spatiotemporal distributions. Compared with the bandpass filter treatment, source separation achieved higher confidence levels under high-intensity noise interference. In some cases, individuals from different bearing angles could be distinguished from mixed acoustic events following TDOA enhancement. Our results support that source separation can effectively improve TDOA estimation by isolating target signals from noisy conditions, with potential applications in estimating abundance and characterizing individual and population-level behavioral dynamics in complex soundscapes.

Abstract

Headwater watersheds in Taiwan are rarely assessed for ecosystem function because they lack discharge gauges, continuous water-quality monitoring and standardized biological inventories. Stream corridors, the lotic and riparian habitats where land-use decisions have the greatest marginal effect, are the least documented. We tested whether indicators derived from secondary data can complement field observation in the Zhongguakeng Creek watershed, Nantou, central Taiwan. From orthophotos spanning six decades we reconstructed a chronology of channel and riparian morphology at 130 transects spaced 100 m along the order ≥3 stream network, and derived composite indicators of four riparian functions: flood and debris attenuation, water-quality buffering, habitat connectivity and bank stabilization. In 2025–2026 we surveyed benthic macroinvertebrates and riparian vegetation across three sites and compared the field metrics with the remotely sensed indicators at reach and sub-basin scales. The orthophoto-derived indicators are compared with the field-surveyed riparian condition and biotic integrity, and the historical chronology provides rich context of fluvial and landscape morphological change. Aligning the two sources yields a transect-resolution, watershed-wide assessment that is repeatable from archival imagery and anchored by field evidence, offering a low-cost basis for prioritizing riparian management in data-scarce watersheds.

Abstract

Snakes are commonly kept in small, transparent, unenriched containers during display, sale, and transport, raising concerns about restricted behavior and welfare. We examined how container size affects behavioral responses of corn snakes (Pantherophis guttatus) under static, simulated vibration, and real vehicle transport conditions. Ten juvenile corn snakes were individually tested in three container sizes (small: 14.5 × 11 × 7.5 cm; medium: 30 × 20 × 15 cm; large: 40 × 30 × 20 cm), with at least 48 h between trials. The first 60 min of each condition were analyzed for stationary and resting behavior. Under static and vehicle conditions, stationary and resting durations were significantly longer in the small container than in the medium and large containers. Under simulated vibration, both durations differed significantly among all three sizes, with the longest durations in the small container and the shortest in the medium container. These findings suggest that smaller containers may facilitate sustained resting and provide greater physical stability during short-term transport, although responses may depend on the pattern and direction of movement.

Abstract

Many organisms use camouflage to avoid predation. Background matching is a camouflage strategy in which the organism hides on backgrounds that resemble their appearance. Other strategies do not require exact background matching, such as masquerade or disruptive coloration. In this study, we investigated the camouflage strategies of a Taiwan-endemic katydid, Trachyzulpha formosana, which exhibits two distinct morphs: one resembling moss and one resembling lichen. We hypothesize that each morph prefers backgrounds that match its own appearance. We evaluated their background preferences using two types of choice experiments: one with images of moss and lichen, and one with real moss and lichen attached to the images. We also applied visual modeling to determine whether predators can distinguish katydids from their backgrounds. In both experiments, moss-morph katydids showed a preference for moss background. Lichen-morph katydids also showed a preference for moss, but only in the experiment with real substrate. Visual modeling suggests that predators can distinguish both katydid morphs from non-matching backgrounds, but not from matching backgrounds. Our results reveal a mismatch between appearance and substrate choice. Only the moss morph selected its matching background, suggesting that the lichen morph may rely on other camouflage mechanisms.

Abstract

Species accumulation curves (SACs) are essential macroecological tools for estimating regional species richness, yet their accuracy is constrained by data input order and the subjective choice of extrapolation functions. While standard randomization methods minimize ordering bias, they often obscure vital ecological structures that contain valuable predictive information. This study is a new attempt to incorporate nested community structures to enhance the predictive power of SAC fitting methods, using comprehensive Taiwanese avian dataset as a prime example. We evaluated the degree to which ordering data based on nested structures—rather than randomized inputs—improves total species richness estimates. These data-ordering methods were fitted to negative exponential, logarithmic, and Clench functions at multiple spatial scales, including national level and 10x10 km grid cells. Ordering data based on nestedness is expected to detectably increase the predictability of species richness at finer spatial scales, especially coupled with the logarithmic function, due to a perfect complementary effect between community structure and mathematical model. This study aims to demonstrate that leveraging non-random ecosystem heterogeneity, such as nestedness, transforms subjective empirical choices of prediction curves into an objective, data-driven framework to optimize sampling efforts and accurately assess biodiversity in complex, species-rich island landscapes.

Abstract

The species composition of communities in ecosystem can be influenced by environmental or climatic factors. Biodiversity may also change due to the impact of global warming. To understand the relationship between species diversity and climatic factors, researchers often use species diversity analysis to construct statistical model between climatic factors and species richness estimates, aiming to explore the relationship between variables, and to evaluate model performance. However, the suitability of using estimated species richness as the response variable in diversity analysis has rarely been systematically discussed in previous studies. The methods for estimating species richness as response variables are evaluated and compared based on regression coefficient estimates, test statistics, and the significance rate of explanatory variables. The simulation results show that, for regression coefficient estimation, under the condition of minimizing bias, the parametric species richness estimators, Gamma-Poisson-based (𝐺𝑃), is considered more suitable as response variables for species richness diversity analysis in abundance data. For model test statistics, the standardized species richness estimation method based on sample coverage, yields test statistics closer to the true model, making it more suitable as a proxy for the test statistics of number of species in communities.

Abstract

Understanding how competing species coexist despite the competitive exclusion principle has long been a central question in ecology. Recent studies have highlighted two factors that strongly influence competition and coexistence: mutualistic interactions and rapid evolution. However, how these two factors jointly shape competitive dynamics remains unclear. Using a three-species Lotka–Volterra model with two competitors and one mutualist, we show that rapid evolution of the mutualist can drastically alter coexistence outcomes. We model the evolution of two mutualistic traits: total mutualistic investment and partner preference. Evolutionary changes in these traits generally reduce niche differences within the framework of modern coexistence theory, thereby shrinking the parameter space that permits coexistence and promoting either competitive exclusion or priority effects, whereby early-arriving species monopolize niches. Consequently, models that ignore evolutionary dynamics may substantially overestimate the potential for coexistence. Our results demonstrate that the effects of mutualism on species coexistence are evolutionarily dynamic and underscore the importance of incorporating rapid evolution of species interactions into modern coexistence theory.

Abstract

A species’ growth rate when rare, known as its invasion growth rate, helps ecologists understand species persistence and coexistence. However, estimating this rate becomes challenging when individuals differ in their life stages or other states. For example, a stage-structured population introduced as juveniles may initially decline, while the same species introduced as adults may increase, making initial growth an unreliable indicator of long-term invasion success. We developed a unified framework for distinguishing these transient responses from long-term population growth while the invader remains too rare to alter its environment. Using a stage-structured competition model as an example, we showed that populations with different initial stage compositions converge to the same invasion growth rate once transient differences in stage composition disappear. With this insight, we demonstrated how analytical expressions of the invasion growth rate can be derived using timescale separation and matrix theory. Mathematical calculations and computer simulations yield consistent estimates in our worked example. We further applied the framework to models of intraguild predation, plant–soil feedback, and parasitoid interactions, illustrating how invasion growth can be quantified in structured population models when individuals differ in developmental stage, soil environment, or infection status.

Abstract

Pollinating insects are decreasing worldwide due to various environmental stresses (so-called pollinator crisis), raising concerns that plant productivity could be undermined in natural and agricultural ecosystems. To date, however, few studies have reported a concurrent decline in both pollinators and plants, and little is known about when a “plant crisis” occurs. Here, we propose that anthropogenic environmental stresses on pollinating insects (e.g. climate change, habitat loss, and pesticide usage) can negatively affect herbivorous insects (e.g., pollinator larvae and crop pests) as well, and effects of pollinator declines may be masked by positive effects of herbivore declines. To test the idea, we theoretically investigated plant population dynamics mediated by two insect groups: one representing a pollinator that is mutualistic at the adult stage but antagonistic at the larval stage, and the other representing a non-structured pest herbivore. Our model revealed that environmental stresses (increasing insect mortality) can have counterintuitive effects on plants. Nonetheless, plant abundance generally decreases with decreasing pollinator abundance, especially when plant populations grow slowly without pollinators, when pollinators are effective mutualists, or when pollinators are susceptible to environmental stresses. These findings offer a theoretical basis for assessing the pollinator crisis for biodiversity conservation and agricultural management.

Abstract

Predators play diverse and crucial roles in determining the structure and dynamics of ecological communities. Human activities, such as overexploitation and habitat destruction, drive the decline and extinction of apex predators. The decline of apex predators often triggers mesopredator release (the population surge of mid-ranking predators). Consequently, shared prey populations can decline even further than before the apex predator's loss. This phenomenon, known as the mesopredator release effect, poses a significant challenge for biodiversity conservation involving predator management. However, the impact of losing apex predators extends beyond merely reducing direct predation on mesopredators. Mesopredators frequently scavenge carrion left by apex predators; thus, the loss of these carrion providers can negatively affect them. Conversely, scavenging often increases the mesopredator's risk of direct predation by the very apex predator providing the meal. Therefore, this provisioned carrion acts as a "fatal attraction" for mesopredators. In this presentation, we use a mathematical model to theoretically analyze how carrion provisioning and its fatal attraction influence the dynamics of mesopredator release and its subsequent effects on shared prey populations.

Abstract

Death-feigning is an anti-predator trait in which prey remains motionless to distract predator. It is known that the duration time of death-feigning is often consistent within an individual but varies among individuals within a population. It is also known that duration evolves to become longer in the presence of predators. From them, we can gain two questions. Firstly, why is there a variation among population? Secondly, how the population dynamics of preys and predators and the evolutionary dynamics of duration time interact? To solve them, two models have been developed.

To solve the first problem, I made a hypothesis. That is “Prey survives by death-feigning making someone moving decoy”. By using the framework called “War of attrition game”, I verified the hypothesis. Consequently, it turned out that there was no single optimal duration time and the exponential distribution was a stable distribution within the population.

Eco-evolutionary dynamics was used to solve the second problem. Analyzing this system, it turned out that the evolution of prey could affect the maintenance of predators’ population.

This study can explain how the variation of defensive traits is made and how the evolution of it affects the population dynamics.

Abstract

Batesian mimicry allows palatable prey (mimics) to avoid predation by resembling unpalatable prey (models). Natural selection is therefore expected to increase mimetic accuracy. However, the accuracy of Batesian mimicry varies widely, from perfect to imperfect resemblance, and some species exhibit dimorphisms between mimetic and non-mimetic phenotypes within a population. To identify the ecological conditions generating such diversity of Batesian mimicry, we constructed and analyzed eco-evolutionary dynamics of Batesian mimicry (Tomizuka & Tachiki 2026 Am. Nat.). Predator discrimination under uncertainty about prey palatability was modeled using signal detection theory. We assumed that acquiring mimetic traits was associated with a physiological cost, creating a trait space with two adaptive peaks corresponding to mimetic and non-mimetic phenotypes. We found that the carrying capacity of models was the primary determinant of evolutionary outcomes.

As the carrying capacity of models increased, the evolutionary outcome shifted sequentially from non-mimicry to dimorphism, perfect mimicry, and imperfect mimicry. Dimorphism evolved when the carrying capacity of mimics slightly exceeded that of models, with evolutionary branching allowing stable coexistence of mimetic and non-mimetic phenotypes. Our results reveal that distinct states of Batesian mimicry can emerge from a single eco-evolutionary framework that links predator decision-making, population dynamics, and phenotypic evolution.

Abstract

Soil microbial effects from plant conditioning are key drivers of plant community competitive dynamics, and negative microbial effects are known to promote plant coexistence. However, previous studies have rarely considered the conditioning duration, despite evidence that plant–soil feedback strength may vary across ontogenetic stages. We conducted a greenhouse experiment using Bidens pilosa and Youngia japonica, where we let the two species condition the soil until either the pre-flowering or post-flowering stage. Seeds of the two species were then sown in soils with different conditioning histories. During germination, negative microbial effects were consistently weaker in soil from the pre-flowering stage than from the post-flowering stage. However, during the growth phase, microbial effects were strongly negative in soil from the pre-flowering stage, while those of the post-flowering stage shifted towards positive. In addition, we used a patch occupancy model to examine how stage-dependent microbial effects drive community dynamics. We found that seedling-conditioned negative microbial effects determine whether plant populations can persist in the system, while adult-conditioned microbial effects further regulate the size of the parameter space allowing plant coexistence. Overall, our empirical and theoretical results show that conditioning duration linked to ontogeny plays an essential role in plant community dynamics.

Abstract

A microbial population's spatial scale fundamentally depends on its dispersal capacity. Because bacteria rely heavily on passive transport via environmental vectors (e.g., wind and water) or macroorganisms, we hypothesize that dispersal limitation inherently drives genetic divergence among Bradyrhizobium lineages across different spatial contexts. This limitation potentially shapes distinct genomic features even within the same plant host genus, Grona, a native Taiwanese legume. However, environmental filtering, such as soil chemical composition, can disrupt this expected pattern. Resolving the antagonistic forces between local selection and gene flow in microorganisms remains an important yet unsolved evolutionary challenge. To address this, we apply a reverse ecology approach by isolating symbiotic Bradyrhizobium strains from diverse geographic locations for whole-genome sequencing. Following de novo genome assembly, we will define the accessory genomes characterizing each bacterial population. Furthermore, genetic neutral sites will be aligned and analyzed to determine whether a distinct pattern of isolation by distance exists across the sampled regions. By elucidating these underlying genetic units within this non-model legume-rhizobia system, we aim to robustly redefine rhizobial population structures and rigorously evaluate the true ecological drivers shaping their symbiotic diversity.

Abstract

Bird’s nest fern (Asplenium nidus) is a common tropical and subtropical epiphyte whose bowl-shaped base provides habitat for microarthropods. We investigated microarthropod community succession within bird’s nest ferns, isolating community changes from those associated with vegetation turnover. From a Cryptomeria japonica plantation in northern Taiwan, we sampled 9 small and 9 large fern individuals to represent relatively early and late successional stages of microarthropod communities. Our findings indicated that species addition, rather than turnover, was the major process driving microarthropod community succession. Species composition and community dispersion differed significantly between small and large ferns, with large ferns exhibiting a significantly lower community dispersion and thus community convergence during succession. Oribatida and Collembola were the first and second most abundant taxa regardless of fern size. However, the relative abundance of Oribatida decreased from small to large ferns, while that of Collembola increased. This shift may reflect greater tolerance of Oribatida to the harsh environment during early succession and the addition of Oribatida predators during late succession. Together, our results highlight bird’s nest fern as a useful model system for studying microarthropod succession.

Abstract

Bryophytes are non-vascular plants, sensitive to environmental conditions, and prefer to grow in humid conditions. The mountain cloud forest provides a cooler, humid environment suitable for bryophytes to occupy different habitats. Although bryophytes can persist in different habitats, the microclimate conditions might be different across habitats and fog-frequency gradients, and interact with the substrate type and bryophyte community. We want to figure out the interaction between fog and bryophyte community composition and measure functional traits to understand bryophyte persistence strategies across habitats. We collected species composition and environmental data along a horizontal transect in Northern Taiwan, with 81 microplots established across three microhabitats (tree trunks, soil, and decade wood). The environmental data show a distinct pattern along the fog frequency gradient, and the three habitats have different patterns. The mixed-effects model shows that fog and microhabitat interact with bryophyte richness, and the PCA shows that bryophyte species composition clusters by microhabitat, suggesting that community composition changes across microhabitat types.

Abstract

Moso bamboo expansion may alter forest water cycling, but its effects on evapotranspiration remain uncertain. We measured sap flux at four bamboo stands in Japan and Taiwan and developed a canopy conductance model to compare water use between bamboo forests and conifer plantations. Annual stand transpiration ranged from 460 to 560 mm, with seasonal variation largely corresponding to vapor pressure deficit. A common model incorporating responses to vapor pressure deficit, solar radiation, and temperature reproduced transpiration at the three Japanese sites but underestimated it at the Taiwanese site, suggesting additional influences such as culm age structure. We then combined modeled transpiration with published estimates of rainfall interception to compare evapotranspiration between bamboo forests and conifer plantations under standardized meteorological conditions. The comparison suggested that differences depended on stand density: bamboo forests could have higher evapotranspiration than sparse conifer plantations but lower evapotranspiration than dense plantations. These findings suggest that the hydrological consequences of bamboo expansion depend on the structure of the vegetation being replaced and highlight the need to consider stand characteristics when assessing changes in forest water use.

Abstract

The Cucurbitaceae family comprises approximately 90 genera and 950 species, most insect-pollinated and monoecious or dioecious. Floral traits vary widely in shape, size, color, and odor. Fruits are typically fleshy, varying widely in size and shape. Floral display attracts pollinators, and increased pollination frequency and pollen load promote fruit enlargement and seed production. We hypothesized that there’s a correlation between the traits in fruits and pollinator-attracting floral traits in cucurbits. In this study, using 10 species and 1 variety of wild Cucurbitaceae plants distributed across the subtropical, warm-temperate, and temperate zones of the Japanese archipelago, we analyzed floral traits associated with fruit size and seed production.

Results show significant interspecific variation in floral morphological traits related to pollinator attraction, such as flower display size and petal length (PC1: 64.7%), and in pollen grain size and number. Seed numbers per fruit ranged from a maximum of 108.6 ± 24.9 (Trichosanthes multiloba) to a minimum of 1.3 ± 1.2 (Schizopepon bryoniifolius). Although significant variation in fruit size was observed among species (PC1: 85.2%), it showed no strong correlation with seed number. This presentation reports whether floral traits related to pollinator attraction explain interspecific variation in seed production.

Abstract

Non-destructive environmental DNA (eDNA) sampling methods have recently gained attention for surveying biological communities on woody plants. Although several non-destructive eDNA sampling methods have been developed, few studies have compared the biological communities detected by different methods on the same plants. Here, we compared two non-destructive eDNA sampling methods, wipe sampling and stemflow collection, on woody plants. Biological communities detected by each method were analyzed using DNA metabarcoding to evaluate the applicability of these methods to community monitoring. We primarily focused on arthropod communities, while fungi, mammals, and birds were also targeted. eDNA samples were collected from three Quercus serrata trees from April to August 2021 in a satoyama area of the Faculty of Agriculture, Kindai University, Nara, Japan. Arthropod DNA was detected using both eDNA sampling methods. A total of 12 arthropod species were identified by wipe sampling and 18 species by stemflow collection. Trombidiformes, Hemiptera, and Lepidoptera had high read numbers in the wipe samples, whereas Lepidoptera and Symphypleona had high read numbers in the stemflow samples. Fungal eDNA is currently being analyzed, and the results for fungi and other taxonomic groups will also be presented at the conference.

Abstract

When plants are attacked by herbivores, they release volatile compounds known as herbivore-induced plant volatiles (HIPVs). The composition and emission patterns of HIPVs vary depending on herbivore species, density, and time since the onset of herbivory. Exposure to HIPVs can also alter volatile emissions from neighboring undamaged plants. This study aimed to characterize temporal changes in volatile emissions from komatsuna (Japanese mustard spinach), Brassica rapa var. perviridis, during infestation by the green peach aphid, Myzus persicae (Sulzer), and to examine their relationship with aphid abundance. We also examined temporal changes in volatile emissions from adjacent plants without experimental aphid introduction. Under greenhouse conditions, M. persicae was introduced onto komatsuna plants, and aphid abundance and plant volatiles were monitored for approximately one month. Plant volatiles were collected three times per week from aphid-introduced plants, adjacent plants without experimental aphid introduction, and aphid-free plants protected with insect-proof mesh. Samples were analyzed by gas chromatography–mass spectrometry (GC–MS), and detected peaks were tentatively identified using an MS database. Principal coordinate analysis (PCoA) was used to examine temporal patterns in volatile profiles among treatments based on peak-area data.

Abstract

The fire ant Solenopsis invicta provides a powerful model to study the genetic basis of social behavior. Its colony structure—having a single-queen (monogyne) or multiple-queens (polygyne)—is determined by a “social supergene’’. This supergene contains hundreds of genes, including those for odorant-binding proteins (OBPs) like Gp-9 and enzymes for cuticular hydrocarbon (CHC) synthesis, which are hypothesized to control queen recognition. This project aims to functionally validate this model by using novel CRISPR-Cas9 delivery methods (ReMOT Control, DIPA-CRISPR, Vitellotag) to enable high-throughput mutagenesis of key candidate genes. We will first optimize these techniques by targeting the visible marker gene cinnabar, then apply the most efficient method to disrupt specific OBPs (e.g., OBP12b') and desaturase enzyme genes potentially involved in CHC production or detection. The resulting phenotypic changes in worker behavior and colony social organization will be assessed. This functional genetic approach will directly test the role of specific supergene components in orchestrating complex social traits.

Keywords: social chromosome “supergene”, odorant-binding proteins, cuticular hydrocarbon.

Abstract

In most ant colonies, workers are sterile, yet their labor is essential for colony survival. Since all workers are diploid females while males are typically haploid and do not perform worker tasks, proper sex determination is crucial for colony function. We have confirmed that the fire ant, Solenopsis invicta, uses complementary sex determination (CSD). QTL mapping indicates that the primary sex determination locus likely contains a novel non-coding gene rather than the homologs of known hymenopteran primary sex determination genes. The fire ant candidate primary sex determination gene maps to a 15kb region, which corresponds to a hypervariable region within a conserved syntenic genomic position across hymenopteran lineages. We annotated the region and also generated RNA-seq which revealed a long non-coding RNA, HVRt. We also used ATAC-seq to examine the chromatin accessibility pattern within this region. RT-PCR experiments also suggest the expression of HVRt is detectable at the earliest stage of embryonic development, consistent with the expected timing of a primary sex determining signal. Currently, we are conducting CRISPR/Cas9 mutagenesis and RNA interference experiments to test if HVRt is the primary sex determination gene in the fire ant.

Abstract

Dispersal of social insects involves independent colony foundation (ICF) and dependent colony foundation (DCF). ICF enables long-distance dispersal but has low founding success, whereas DCF has the opposite trade-off. The ant genus Myrmecina is notable for its diversity of queen morphology and dispersal strategies. We discovered that Myrmecina amamiana has three distinct queen morphs: large and small alate queens (LAQ and SAQ, both winged) and ergatoid queens (EQ, permanently wingless). Field surveys, dissections, and morphometric analysis revealed distinct social characteristics related to queen morphs. The numbers of ovarioles in LAQ, SAQ, EQ, and workers are 4.3 ± 0.6, 4.2 ± 0.4, 6.1 ± 0.3, and 2.2 ± 0.6, respectively. Colonies were small (12.4 ± 9.1 workers) and nested preferentially in shallow (<10 cm), compact clay outcrops. AQ-monogynous, EQ-monogynous, EQ-polygynous, and queenless colonies were found, but no AQ-polygynous or AQ-EQ mixed colonies occurred. AQ and EQ were produced exclusively in AQ and EQ colonies, respectively. SAQ tends to be produced in smaller AQ colonies while LAQ is produced in larger AQ colonies. To our knowledge, this is the first known case of three distinct queen morphs in ants, suggesting remarkable reproductive polymorphism.

Abstract

Cleptobiosis in ants is a form of compound nesting in which one species steals food from another, yet host dependence and host impacts remain poorly understood. We investigated the cleptobiotic association between the attine ant Strumigenys incerta and its ponerine host Cryptopone sauteri. Field surveys showed that S. incerta nested exclusively within C. sauteri nests, and laboratory rearing showed substantial colony growth only in the presence of the host. Behavioral assays revealed that S. incerta primarily stole prey temporarily stored by host workers and rarely hunted independently. After host removal, workers attempted to hunt, but their success was significantly lower than that of congeneric species, indicating strong dependence on cleptobiosis for food acquisition. Host aggression toward S. incerta was rare, and S. incerta typically remained motionless with retracted appendages during encounters. Cuticular hydrocarbon analyses showed distinct profiles between the species, providing no evidence for chemical mimicry. The presence of S. incerta had no detectable effect on host colony growth. These findings indicate that S. incerta is an obligate cleptobiont and that its association with C. sauteri is close to commensalism.

Abstract

Many ant species live at high densities in enclosed nests, where the introduction of pathogenic microorganisms can potentially lead to disease transmission among colony members. To reduce such risks, ants have evolved diverse forms of social hygiene behavior, collectively referred to as social immunity. Here, we focused on fecal waste, a potential carrier of pathogenic microorganisms and investigated how ants manage feces within the nest. First, using the ponerine ant Diacamma cf. indicum, which is known to deposit feces collectively in designated toilet areas, we examined the mechanisms underlying toilet formation through behavioral experiments. We then conducted simulations incorporating fecal odor and nest spatial structure. Our results suggest that, in D. cf. indicum, fecal odor promotes fecal aggregation, whereas toilet location is strongly influenced by spatial features of the nest. Finally, we examined toilet formation across 40 ant species and found that clearly defined toilet areas were formed in almost all species tested. Together, these results suggest that spatially organized fecal management is widespread among ants and may represent an important component of social hygiene within the nest.

Abstract

In many animals, individuals engage in contests over resources such as food and mating opportunities. However, lethal fights are rare because the conditions favoring their evolution are limited. The spider mite is a group that includes several species showing lethal male-male fights. Because these species maintain many unmated females within their silk nests, winner males monopolize females capable of mating. At present, however, few studies have reported proximate factors that cause such fights. We established four experimental treatments: a nest containing an egg, a nest containing a female, a nest without an occupant, and no nest, and compared the proportions of lethal male–male fights among the treatments. In this study, we investigated whether the frequency of lethal fights in Schizotetranychus brevisetosus Ehara depends on the female age or the presence of the nest itself, and demonstrated that lethal fights were affected only by the nest presence. These results suggest that males fight to defend the nest, which provides future mating opportunities.

Abstract

Phoresy is a dispersal strategy in which animals use another species for transportation. Phoresy occurs in various taxa, but is most common among small arthropods. However, the behavior of phoretic animals from attachment to detachment has not been well described.

Pseudoscorpions form phoretic associations with a wide range of hosts, such as Coleoptera, Diptera, and Hymenoptera. In this study, we report phoretic behavior in a Haplochernes sp. (Chernetidae) under laboratory conditions.

When pseudoscorpions and longhorn beetles (Chlorophorus japonicus or Monochamus subfasciatus shikokuensis) were placed together in a Petri dish, pseudoscorpions attached to the beetles’ antennae or legs. These individuals were also observed repeatedly swaying their bodies while grasping the beetles with their pedipalps. Furthermore, they moved along the beetles’ antennae using their pedipalps.

This behavior may be involved in maintaining phoresy by selecting a position on the host.

Abstract

This study used a portable spectrometer to characterize peak emission wavelength (λmax) and luminescent intensity of 20 native and one introduced firefly species in Taiwan, combined with cytochrome oxidase I (COI) barcoding to clarify phylogenetic relationships. Average λmax ranged from 551 nm (green-yellow) to 579 nm (yellow-orange), with Lampyrinae showing narrower ranges than the more diverse Luciolinae. Mean luminescent intensity ranged from 0.1–3.2 lux, with Abscondita cerata and Pyrocoelia analis among the brightest species. Ambient light measurements confirmed that fireflies began flashing at 2–10 nW/cm² and took flight below 0.2–1.5 nW/cm², supporting flash intensity as a nocturnal activity cue. Phylogenetic analysis revealed substantial taxonomic ambiguity, including paraphyly within Abscondita, Luciola, Aquatica, and Curtos, and between Diaphanes and Pyrocoelia. Several public Chinese COI sequences were identified as likely misidentifications, while new sequences from China and Southeast Asia resolved monophyly in Abscondita. Additional cryptic lineages were detected within Luciola, Aquatica, and Curtos, suggesting underestimated regional diversity. These results show that integrating portable luminescent measurements with COI barcoding provides a robust framework for firefly taxonomy and habitat characterization, offering practical parameters for firefly-friendly habitat design and emphasizing careful species verification before public database submission.

Abstract

Kin recognition plays a crucial role in mating across diverse taxa by helping prevent inbreeding. In humans, surnames have historically served as indicators of kinship, and same-surname marriages were prohibited or discouraged in some societies. Here, we tested whether surnames still influence partner choice in modern society using nationwide name databases from Taiwan. In 2018, same-surname marriages occurred less frequently than expected, consistent with historical taboos against such marriages. However, this pattern was absent in 2023, suggesting a recent shift in social attitudes. To further explore this trend, we conducted a questionnaire survey among university students. Attractiveness ratings of opposite-sex face images were not significantly affected by whether the surname matched that of the respondent, contrasting with traditional customs. Although preliminary, these results suggest that the role of surname match or mismatch in partner choice may be diminishing under rapidly changing socio-cultural conditions. Further studies across regions and generations are needed to clarify how modernization and globalization reshape the role of surnames in human mate choice.

Abstract

Cave-dwelling organisms exhibit extremely low dispersal ability due to specialized adaptations to subterranean environments, including the reduction of eyes and wings, making them suitable models for studies of speciation and biogeographic history. Among them, cave trechine beetles (Carabidae:Trechini) frequently form distinct lineages restricted to individual cave systems.

Shikoku Island is a hotspot of trechine diversity in Japan, harboring 17 of the 32 genera known from Japan, including eight endemic genera. One of these, the genus Ryugadous, has been divided into the subgenera Ryugadous and Yuadorgus based on morphological characteristics, but their phylogenetic relationships have not been tested using molecular data.

In this study, we investigated the relationships between the two subgenera using comparative morphology and molecular phylogenetic analyses. Maximum likelihood and Bayesian analyses of nuclear and mitochondrial DNA sequences recovered Ryugadous as a monophyletic lineage, with Yuadorgus positioned outside this clade. Morphological comparisons revealed that species of Ryugadous possess large and complex copulatory pieces with well-developed teeth patches, whereas Yuadorgus exhibits simpler genital structures. Our results are consistent with the previous taxonomy and provide a basis for future studies of the evolution and biogeography of subterranean beetles in Shikoku.

Abstract

Species delimitation in Caenorhabditis nematodes is commonly based on an initial assessment using sequence identity at the ITS2 barcode and confirmed by mating tests for compatibility. To date, when two independent isolates, or strains, have ITS2 sequence identity <96.0%, they have always been different species. In contrast, strains with >99.0% identity have reliably indicated reproductively compatible. We have been using this framework to study the biodiversity of Caenorhabditis in Taiwan and Southeast Asia, and here we report our recent surveys results. Interestingly, for three strains ITS2 sequence identity was >96% to its nearest species, but the closest pairs were reproductively incompatible in all cases. Because ITS2 is only one nuclear sequence, we sequenced, assembled, and annotated the mitochondrial genomes for these three strains. Mitogenomic phylogenetic analysis matched the ITS2 analysis for two strains but not a third, indicating that these two markers can conflict. Overall, we have identified three new cryptic species. Our results raise the possibility that other cryptic Caenorhabditis species have already been isolated but assigned incorrectly to known species based on high ITS2 sequence identity.

Abstract

Gonadotropin-releasing hormone (GnRH) signaling regulates diverse physiological processes across bilaterians. It primarily regulates sexual maturation in deuterostomes and energy metabolism in protostomes, but its ancestral function and how it diversified during evolution remain unclear. To clarify the evolutionary origin of GnRH signaling, we investigated two early-diverging bilaterian models: the acoel Praesagittifera naikaiensis and the polyclad flatworm Comoplana pusilla. Phylogenetic analysis revealed that acoel GnRH receptors cluster with vertebrate GnRHRs, whereas polyclad flatworm receptors group with arthropod corazonin receptors. In both animals, GnRH family peptides are synthesized in neurons of the central nervous system. Moreover, low-temperature treatment increased GnRH transcript levels in both species. Despite this shared temperature responsiveness, downstream functional responses differed between the two species: in acoels, GnRH peptide administration increased expression of the germline marker (nanos) and promoted reproductive organ development. In contrast, GnRH treatment in polyclad flatworms suppressed the expression of energy metabolism-related gene without affecting nanos expression. These results indicate that low-temperature responsiveness is a conserved feature of ancestral GnRH signaling, whereas its downstream physiological functions have diversified among bilaterian lineages. Our findings suggest that the functional divergence of GnRH signaling into deuterostome-type (sexual maturation) and protostome-type (metabolic regulation) may have occurred around the protostome-deuterostome split.

Abstract

How do marine communities respond when the ocean becomes exceptionally warm, and does cooling bring them back? Modern observations capture rapid ecological change, but rarely span the full course of disruption and recovery. Fossil records offer a unique, longer view. We use tiny fish otoliths preserved in deep-sea sediments to reconstruct lanternfish communities in the tropical western Pacific across six exceptionally warm periods. We found that lanternfishes are abundant members of ocean food webs, and that their fossils allow us to track changes in fish production, diversity, community composition, and body size over hundreds of thousands of years. Our record links extreme warmth to declines in fish production and diversity, accompanied by shifts in body-size structure. We develop a biomass-flux proxy, asking whether shifts toward larger fish can conceal a decline in the fish mass represented through time. Differences between pre- and post-warming size distributions also raise the possibility of delayed or altered recovery. By comparing events with contrasting warming histories, we examine how warming intensity, duration, and rate relate to ecological disruption, and whether different aspects of community structure and biomass flux recover together during subsequent cooling. The central question is not simply whether fish communities decline under extreme warmth, but how they reorganize and whether the communities that emerge afterward resemble those that came before. These deep-time records provide a long-term perspective on the vulnerability and resilience of marine ecosystems in a warming world.