Biotropica

AimHuman land-use has dramatically altered the amount, quality, and connectivity of habitat for species worldwide. Understanding how these changes affect individual species is essential for predicting the overall consequences of land-use change for biodiversity. LocationThe Caribbean island of Puerto Rico. Forest cover on the island increased from about 18 to 45% from the late 1940s to the early 2000s. MethodsUsing data on geographic distributions and functional traits for 454 tree species, we evaluated how gain of potential habitat was related to species-specific climatic associations and life-history strategies. We estimated species-specific potential habitat (climatically suitable and forested) with species distribution models and data on forest cover. We characterized each species niche breadth (the range of environmental conditions it occupies) and niche position (the environmental conditions it prefers) to compare with the conditions in reforested areas. ResultsSpecies with relatively more potential habitat in 1951 (climatically suitable and forested) also had relatively larger gains in potential habitat from 1951 to 2000. Species that tend to occupy conditions different from those common in reforested areas (i.e., more marginal habitats) gained relatively less potential habitat and species with broad environmental niches gained more potential habitat. Additionally, species with relatively acquisitive functional traits gained more suitable habitat than those with relatively conservative traits. Main conclusionsOur results show that Puerto Ricos reforestation preferentially increased habitat for species that (1) already had suitable habitat in the landscape, (2) tolerate a wide range of climatic conditions, and (3) exhibit fast, acquisitive functional strategies. These findings illustrate how land-use change in heterogeneous tropical landscapes can generate non-uniform habitat gains across species, potentially favoring generalist over specialist species and reshaping community composition.

Stingless bees are key pollinators in tropical ecosystems, yet their ecological dynamics remain poorly understood in highly seasonal environments such as the seasonally dry tropical forests of Ecuador. These ecosystems experience pronounced climatic seasonality, with sharp transitions between dry and wet periods that strongly affect floral resource availability. Understanding interspecific competition and niche partitioning in such systems is critical, particularly given the global decline of pollinators. We investigated resource use and niche dynamics in two native stingless bees, Melipona mimetica and Scaptotrigona sp., by quantifying pollen, nectar, and resin collection across seasons. Log-linear models were used to test the effects of species, season, and their interaction on resource use, while non-metric multidimensional scaling (NMDS) assessed niche overlap. Contrary to the expectation that niche overlap increases under resource scarcity, we found greater overlap during the wet season, when resources are more abundant. This suggests that both species converge on high-quality floral resources during peak availability, reflecting an adaptive response to strong environmental seasonality. Pollen use remained stable across seasons, consistent with generalist foraging behavior. In contrast, nectar collection increased significantly during the wet season, while resin exhibited a shared seasonal peak, likely associated with synchronized nest construction or maintenance. These findings reveal context-dependent competition dynamics and highlight the role of environmental seasonality in shaping pollinator interactions. Our study provides new insights into the ecology of threatened stingless bees and contributes to their conservation in tropical dry forest ecosystems.

O_LIMegaherbivores are increasingly promoted as agents of nature restoration, yet most research on their ecological effects has focused on temperate and non-forested systems, with limited consideration of tropical forests and their historical land-use contexts. C_LIO_LIA better understanding of megaherbivore impacts in tropical forests is essential to inform rewilding and restoration efforts. This is particularly important in regenerating secondary systems that historically supported megafaunga and remain highly valuable targets for ecological recovery. C_LIO_LIWe address this knowledge gap by comparing tree species composition, forest structural attributes, and understory habitat composition across three disturbance regimes in an East African tropical dry forest: (1) primary forest with megaherbivores, (2) secondary forest with megaherbivores, and (3) primary forest without megaherbivores. C_LIO_LIUnder megaherbivore presence, understory habitat and tree branching architecture converged across primary and secondary forests, suggesting functional consistency in disturbance effects imposed by large herbivores and indicating that key structural ecosystem processes can be rapidly restored. In contrast, canopy structure and tree species composition remained distinct between forest types and strongly constrained by persistent legacies of past human land use. C_LIO_LIOur findings underscore that restoration strategies relying on megaherbivores must explicitly account for historical land-use constraints rather than assuming spontaneous convergence toward primary-forest conditions. C_LI

In relatively aseasonal tropical rainforests, few studies have explored long-term phenological patterns of a high diversity of tree species in relation to climate, phylogeny, and functional traits. In these systems, short-duration seasonal pulses of irradiance and water deficit are expected to provide narrower windows for leafing and flowering and wider windows for fruiting across prolonged wet seasons, potentially mediated by functional traits and phylogenetic relatedness. Here, we document leafing, flowering, and fruiting phenology of 50 tree species (920 - 1077 trees, 10 - 42 trees/species) monitored monthly over an 9-y period (2017 - 26) in a relatively aseasonal south Asian tropical rainforest in the Anamalai Hills, Western Ghats, India. We examined correlations between climatic variables (irradiance, daylength, temperature, precipitation) and tree phenology and Mantel correlations among similarity in monthly phenology, functional traits (wood density, seed size, and maximum height), and phylogenetic relatedness. We then investigated the phylogenetic signal of phenological traits (frequency, amplitude, duration, and peak month) using Pagels {lambda}. Leaf flushing and flowering showed distinct seasonality and negative associations with daylength and precipitation, whereas fruiting showed greater temporal spread and weaker associations with climate. Functional traits or phylogeny did not significantly influence leaf flushing and flowering, whereas dissimilarity in fruiting was correlated with phylogenetic distance and peak fruiting month showed a significant phylogenetic signal ({lambda} = 0.96). The results indicate that in relatively aseasonal tropical rainforests, proximate climatic cues more strongly influence leaf flushing and flowering, whereas phylogenetic constraints affect timing of fruiting and may cause lineage-specific vulnerabilities to climate change.

PremiseLong-term phenological patterns are increasingly being examined from the perspective of climate change and its potential effects. Climatic effects on plant phenology could involve the direct responses to changes in temperature, precipitation and solar irradiance, or could be mediated by these variables through exogenous teleconnections such as the El Nino Southern Oscillation (ENSO). The effects of climatic fluctuations on inter-annual variation in tropical phenology remain understudied. MethodsWe examined long-term patterns of tree flowering and fruiting intensity in a tropical forest site in the Eastern Himalayas between 2011 and 2024. Species-specific patterns were examined for 36 species. Long-term patterns were quantified using Generalized Additive Models, and splines were visualized to infer trends. Through Generalized Linear Mixed Models, we determined if there was a lagged phenological response to ENSO and temperature, precipitation and solar irradiance, and whether ENSO effects were being mediated through the latter group of variables or plant traits. ResultsBetween 2011 and 2019, trends in flowering and fruiting were significant for 17 and 23 species respectively. Flowering increased for 7 species, while fruiting declined for 8 species. Flowering peaked during El Nino, but this association did not appear to be mediated through climate variables, whereas fruiting showed a three-month positive lagged response to solar irradiance, independent of ENSO. The peak season of reproduction was the only trait determining species-specific responses to climate variables. ConclusionOur study highlights nonlinearity in long-term patterns of reproductive phenology, and the importance of solar irradiance in determining inter-annual fruit production.

Landscape composition is central in shaping how pollinators utilise floral resources, yet its influence on foraging behaviour of co-occurring Asian honey bees remains underexplored. Resolving this gap is crucial to understand how closely-related, native and introduced species maintain foraging efficiency in rapidly changing environments. We investigated nectar preferences, sucrose responsiveness, and foraging task partitioning in three co-occurring honey bee species in India: Apis florea (native open-nesting), Apis cerana (native cavity-nesting), and Apis mellifera (introduced cavity-nesting), across forest, agricultural, and urban landscapes. Landscape type strongly influenced crop sugar concentrations of honey bees. While all species collected high-concentration nectar in forests, A. mellifera and A. cerana collected lower concentrations than A. florea in urban habitats. A. florea showed consistent preference for high-concentration nectar across landscapes. Complementing this, sucrose responsiveness assays revealed a lower responsiveness of A. florea compared to cavity-nesting species. Foraging task partitioning differed among species, but interestingly, also among landscapes. While A. cerana predominantly collected nectar, A. mellifera foraged equally for pollen, nectar and water, and A. florea shifted task allocation across landscapes. In conclusion, we provide the first comparative evidence that landscape composition and species characteristics jointly shape foraging preferences and organisation of foraging labour in Asian honey bees.

AimTo examine how variation in frugivore species richness influences dietary specialisation and the organisation of plant-frugivore interaction networks in tropical forests. LocationSix undisturbed lowland wet tropical forest sites across four biodiversity hotspots in south and south-east Asia. Time period2016-2024. Major taxa studiedAvian frugivores and fleshy-fruited woody plants. MethodsWe recorded plant-avian frugivore interactions across six undisturbed evergreen forest sites spanning a seven-fold gradient in frugivore species richness, while holding forest type and phylogenetic composition broadly comparable. Using over 4,200 hours of focal observations on 551 fruiting plants, we recorded more than 34,000 feeding visits by 138 frugivore species on 133 plant species. We used a) Joint species distribution models to determine the relative influence of fruit and seed traits, and b) network analyses to evaluate how dietary breadth and network properties varied with frugivore species richness. ResultsAcross sites, frugivore visitation was primarily explained by fruit and seed morphology, with seed size accounting for an average of 39.7% of explained variation, followed by fruit width (24.4%), fruit crop size (21.9%), and pulp lipid content (14.1%). Frugivores in species-rich communities exhibited narrower dietary breadth (Pearsons r = -0.87 between normalised degree and species richness). Correspondingly, plant-frugivore networks became less connected and nested, and more modular, with increasing frugivore richness (Pearsons r = -0.9, -0.98, and 0.84, respectively). Main conclusionsIncreasing frugivore species richness intensifies dietary specialisation, which in turn drives changes in plant-frugivore network structure. These findings highlight how local species richness shapes interaction networks through changes in consumer niche breadth, with implications for the organisation of tropical forest mutualistic communities.

O_LITropical dry forests are among the most threatened ecosystems globally, yet the consequences of livestock overgrazing for ant communities remain poorly documented, particularly in the Tumbesian biodiversity hotspot of southwestern Ecuador, where uncontrolled goat grazing constitutes the dominant disturbance agent. C_LIO_LIWe sampled ant communities (Formicidae) across a goat-grazing disturbance gradient in Zapotillo (Loja Province, Ecuador), establishing three disturbance levels (Dense, Semi-dense, and Open Forest) with nine 60 x 60 m plots per level (n = 27) and 486 pitfall traps. Community responses were assessed using abundance-based and presence-absence analyses of morphospecies richness, Hill-number diversity, community composition, beta diversity decomposition, and functional guild structure; vegetation structure was characterized using satellite-derived NDVI. C_LIO_LIWe recorded 47,459 individuals belonging to 22 morphospecies in six subfamilies. Morphospecies richness declined with disturbance (Dense: 19, Semi-dense: 15, Open: 12), with four specialist genera exclusive to Dense Forest. Beta diversity decomposition revealed a shift from turnover-dominated dissimilarity at moderate disturbance to nestedness-dominated dissimilarity at high disturbance, indicating progressive habitat filtering as the dominant community-restructuring process. C_LIO_LICommunity composition differed among disturbance levels (PERMANOVA: F = 4.49, R{superscript 2} = 0.272, p = 0.001) and was correlated with NDVI (r{superscript 2} = 0.341, p = 0.013). Cryptic/soil and Leaf-cutter guilds were nearly eliminated from Open forest while the Opportunist guild expanded markedly, indicating that functional homogenization precedes detectable taxonomic impoverishment. C_LIO_LIOvergrazing drives directional ant diversity loss and biotic homogenization at both taxonomic and functional levels in the Tumbesian dry forest, underscoring the conservation value of intact Dense forest. C_LI

Ungulate movements in arid environments are largely driven by rain events, food resources and surface water availability. In hyper arid areas such as the Namib desert these are patchily distributed, fluctuating and overall sparse. As a result, animals living in these environments need to be highly mobile to exploit the ephemeral and spatiotemporally variable resources. In the past few decades, there has been growing recognition of the importance of wildlife habitat connectivity, and the detrimental effects of linear infrastructure on wildlife and their movements. Barriers, such as roads and fences, block or filter wildlife movements, with severe and sometimes lethal effects on wildlife especially in dry periods or resource-poor environments. In the Greater Sossusvlei Namib Landscape we assessed whether fences impacted ungulate home ranges and movements, and identified particular sections of fences or roads which were most restrictive to ungulate movements. To achieve this, the movements of 12 springbok (Antidorcas marsupialis), 13 gemsbok (Oryx gazella) and 15 Hartmanns mountain zebra (Equus zebra hartmannae) were tracked telemetrically. In general, ungulate home range sizes were smaller in the vicinity of physical barriers. Roads and fences were found to impact ungulate movements considerably in some areas: these included the C14 and C19 main roads that run from the coast to Maltahohe and from Solitaire to Maltahohe respectively, several district roads, parts of the Namib-Naukluft National Park fence, as well as farm fences. While Hartmanns mountain zebra were able to cross some fences, springbok and gemsbok were not as successful, their movements sometimes being completely restricted within farms or along fences until they found a fence gap to cross. The findings highlight which barriers are key to consider for modification to allow for wildlife movement.

AimThe assembly of montane plant communities through time is underlain by historical and abiotic factors. However, the extent of evolutionary connectivity between ancient highland ecosystems and surrounding lowlands remains unclear. Here, we investigate the evolutionary connections between the campos rupestres, a hyperdiverse and fragmented montane vegetation complex in eastern South America, and lowland biomes surrounding it: savannas, rainforests, and seasonally dry tropical forests. LocationEastern South America. Time periodCenozoic. Major taxa studiedFlowering plants. MethodsUsing phylogenetic beta diversity analyses for 13 angiosperm clades, we assess the degree of lineage dissimilarity between campos rupestres subregions and adjacent biomes. We also apply generalized dissimilarity modeling to determine the role of climate, soil, and geographic distance in shaping spatial patterns of phylogenetic composition. ResultsOur results reveal high lineage permeability between campos rupestres and surrounding biomes, with lineage sharing largely reflecting biome adjacency. This pattern is mainly driven by shared climatic conditions, which are the strongest predictors of phylogenetic dissimilarity. Main conclusionsWe highlight the importance of lineage exchange between lowland and montane environments for the assembly of highland floras. By showing that lineage movements across biome boundaries have been common over time and spatial scales, our study challenges the idea that ancient Neotropical mountains are isolated sky-islands. Instead, we emphasize the dynamic nature of montane plant diversity and the pivotal role of climate in shaping evolutionary connections between highlands and lowlands.

Long-term field observations typically are the "gold-standard" for inferences of phenological sensitivities in montane systems but are spatially limited. Herbarium specimens provide broader spatial coverage, but their utility to accurately capture montane phenology remains poorly known. We compared flowering phenology of 45 species inferred from herbarium specimens with comparable data from nearly 50 years of direct observations at the Rocky Mountain Biological Laboratory. Estimates of flowering time and phenological sensitivity to snow density were consistent between herbarium specimens and observations, but observations revealed secondary flowering peaks. Herbarium specimens additionally yielded shallower estimates of phenological sensitivity to spring temperature than did field observations. Across co-occurring species, "early" flowering individuals inferred from herbarium specimens, rather than the mean response across all individuals, may better approximate community-level phenological responses to temperature changes. We conclude that herbarium specimens are reliable resources for closing gaps in understanding phenological variation along elevational gradients of montane systems.

Understanding how species that are threatened with extinction utilise human-modified landscapes is essential for evidence-based conservation. We investigated multi-scale habitat selection by the Forest Owlet (Athene blewitti), an Endangered species, endemic to central India with fewer than 1000 mature individuals, in the Dangs district of Gujarat, the westernmost extent of its range. Using a hierarchical Bayesian occupancy framework, we examined how forest cover and three agricultural land-use types (dry agriculture with trees, dry agriculture without trees, and intensive agriculture) affected occupancy across three nested spatial scales: regional (81 km2), landscape (4 km2), and territory (0.25 km2). At the regional scale, the forest x agriculture interaction term was significantly negative ({beta} = -6.82, 95% CI: -9.87 to -1.59), indicating that owlets favour agroforestry-dominated regions over forest-dominated landscapes. Conversely, at the landscape scale, a significant positive interaction ({beta} = 1.36, 95% CI: 0.41-2.50) revealed synergistic benefits from forest-agriculture mosaics. Agriculture type strongly influenced landscape-scale occupancy: dry agriculture with trees showed positive effects ({beta} = 1.17, 95% CI: 0.43-2.02), whereas dry agriculture without trees had significant negative effects ({beta} = -1.19, 95% CI: -2.28 to -0.29). These findings demonstrate that Forest Owlets are not forest-obligate specialists but occupy complex agroforestry mosaics, requiring multi-scale conservation strategies. We propose that the traditional Malki agroforestry system, which incentives tree retention on farmland, offers conditional compatibility with Forest Owlet conservation, provided that mature cavity-bearing trees and small forest patches are explicitly protected.

Gene flow shapes the demographic stability and evolutionary potential of tropical forest trees, yet its dynamics may differ depending on the temporal scale at which it is assessed. We combined spatial genetic structure (SGS), parentage analyses, and reproductive success metrics to investigate historical and contemporary gene dispersal in four populations of Dicorynia guianensis across French Guiana, encompassing sites differing in environment and management history. A total of 1,528 individuals were genotyped using 66 nuclear and 23 plastid microsatellite markers, enabling high-resolution inference of biparental and maternal gene dispersal. Historical mating and dispersal parameters inferred from SGS revealed marked contrasts among populations. Some populations exhibited high historical gene dispersal distances and weak spatial genetic structure, whereas others showed stronger SGS and long-term aggregative dispersal patterns. Contemporary parentage analyses further highlighted differences in seed and pollen dispersal distances, parent assignment rates, and reproductive skew. In certain populations, pronounced reproductive inequality and reduced effective connectivity were observed, while others displayed more balanced reproductive contributions. By jointly evaluating long-term dispersal legacies and present-day reproductive patterns, our study demonstrates the value of combining indirect and direct genetic approaches to assess population dynamics and conservation status in tropical forest trees. This multi-temporal perspective provides a comprehensive basis for long-term monitoring and sustainable management in heterogeneous tropical landscapes.

O_LIFrugivores vary in their selection of fruit traits and their fruit handling methods, leading to differences in the plant species they consume for fruits. While fruit consumption patterns of birds are relatively well understood, much less is known about those of mammals. C_LIO_LIGiven the wide morphological and physiological diversity of mammals, fruit consumption patterns and fruit traits selected by different mammal groups may vary substantially. C_LIO_LIWe investigated differences in fruit consumption among three mammal groups - primates, herbivores, and carnivores - in Asia based on peer-reviewed and secondary literature. We assessed both morphological traits and taxonomic composition and compared patterns across vegetation types and for figs and non-figs. We found that primates (29%) and carnivores (21%) consumed more unique fruit genera than herbivores (6%). Carnivores and primates shared more fruit genera with each other (17%) than with herbivores. These patterns were consistent across vegetation types and for figs and non-figs. C_LIO_LIMorphological traits such as fruit size, colour, type, habit, seed number, and seed arillation showed no major differences among mammal groups. C_LIO_LIThere was no significant relationship between mammal body size and the mean or maximum fruit diameter consumed. However, among mammals that handle fruits exclusively with their mouthparts, body size was positively related to the maximum fruit diameter consumed. In contrast, for mammals that handle fruits using opposable thumbs (primates), body size showed a negative relationship with the mean fruit size consumed. There was no significant relationship between mammal activity patterns and the colour of the fruits they consumed. C_LIO_LIOur results suggest that fruit consumption patterns among mammal groups are not strongly differentiated by the morphological traits investigated; however, carnivores and primates are more similar in their preferred fruit genera. Moreover, morphological trait selection may be influenced by fruit handling methods. C_LIO_LIHerbivores consumed larger fruits and, like primates, preferred dull-coloured fruits, whereas carnivores more often fed on liana and shrub fruits across a wider colour range C_LIO_LIFuture research should focus on chemical and quantitative visual traits, such as volatile profiles and nutritional composition, to better understand the drivers of mammal fruit consumption. C_LI

West African savannahs provide habitats to diverse species assemblages, yet remain understudied compared to their East and Southern African counterparts. The Niokolo-Koba National Park in southeastern Senegal constitutes one of the largest remaining protected areas in West Africa and supports a mosaic of savannah and forest habitats with a diverse assemblage of medium- and large-sized mammals. Here, we analysed camera-trap data originally collected to monitor predator presence in the northwestern sector of the National Park. We deployed 37 cameras across 37 km{superscript 2} from February 2022 to March 2023, resulting in 13,161 camera-trap-days. We assessed alpha diversity indices and spatiotemporal activity patterns of large and medium-sized mammals across habitat types. Evenness values - the degree to which species abundances are distributed uniformly within a community - were higher in the savannah than in forest habitats, although overall species richness was comparable. In contrast, animal sighting rates were higher in forests than in savannahs. Estimated diel activity mostly corresponded with established species-specific behavioural patterns. Our analyses revealed differential use of certain habitat types across the day, likely driven by spatially segregated sleeping sites and foraging locations. Our results provide a reference for future studies and monitoring efforts and highlight the value of the forest-savannah mosaic for the local species assemblage within the larger ecosystem of Niokolo-Koba National Park.

Mangroves play a crucial role in supporting global biodiversity and ecosystem functioning, yet how their multidimensional diversity interact and respond under diverse stress conditions remains underexplored. To address this gap, using species, environmental, functional trait and forest structural data collected from the permanent sample plot (PSP) network (110 PSPs) of the worlds largest mangrove ecosystem, the Sundarbans, we answer three key questions: (Q1) How are structural, functional, taxonomic, and phylogenetic diversities interconnected? We hypothesized that these diversity components are positively correlated (H1). (Q2) What are the key environmental stressors and how the diversity components are influenced by multiple stressors? We hypothesized that these stressors negatively affect all diversity components (H2). (Q3) What spatial patterns emerge in the distributions of these diversity components? Here we hypothesized that these diversity components vary across space under changing environmental conditions (H3). Our results show that taxonomic, functional, structural, and phylogenetic diversity have varying degrees of interconnection. While taxonomic and structural diversity are strongly correlated, functional and phylogenetic diversity exhibit more independent patterns, suggesting distinct ecological processes shape each dimension. Salinity, elevation, silt, community structure and downstream-upstream gradient (i.e., upriver position) have strong influences on all the diversity components although the magnitude of the influence varies. GAM results reveal that salinity and siltation act as the primary negative drivers for most dimensions; however, functional richness and divergence show a unique positive response to salinity. Furthermore, we found that community structure and upriver position significantly influence diversity patterns, often in a non-linear fashion. Though taxonomic, structural, and phylogenetic diversity show higher values mainly in the moderate and low saline areas, functional richness shows higher values in high saline areas. Overall, our results provide strong support for all the hypotheses. Our findings highlight the importance of holistic approach integrating taxonomic, structural, functional, and phylogenetic dimensions for maintaining biodiversity and ecosystem functions in dynamic mangrove ecosystems and emphasize the need for conservation efforts that target moderate-stress zones to preserve both ecological and evolutionary diversity. HighlightsO_LIExplored the interconnection between four dimensions of biodiversity (taxonomic, structural, functional, and phylogenetic) and how they respond to multiple stressors in the worlds largest mangrove forest. C_LIO_LIHigh salinity and siltation act as the primary environmental stressors that negatively affect overall biodiversity. C_LIO_LIStructural diversity is strongly related to species richness, serving as a key indicator of ecosystem health. C_LIO_LIFunctional and phylogenetic diversity follow independent spatial patterns, promoting the need for multi-dimensional monitoring. C_LI

Natural history collections underpin our understanding of species distributions, yet some historical records remain embedded in modern avifaunal checklists despite limited documentation and no independent verification. One such case concerns the Dusky Parrot Pionus fuscus in Colombia: although reported from specimens collected by Melbourne A. Carriker Jr. in 1942 in the Serrania de Perija, the species has not been observed in the country for nearly eight decades yet continues to be included in national checklists and conservation assessments. We reassessed the validity of this record by applying a multi-evidence framework integrating historic archival reconstruction, specimen-based morphological comparisons, climatic niche analyses, biogeographic limit assessment and contemporary survey-effort data. Historical documentation and morphological evidence based on high-resolution specimen images and associated curatorial records demonstrate that the Carriker specimens correspond to Pionus chalcopterus, not P. fuscus. Climatic niche analyses reveal minimal environmental overlap between P. chalcopterus and P. fuscus, and place the Perija locality within the climatic niche of P. chalcopterus, while regional biogeography and extensive modern birdwatching coverage provide no support for the occurrence of P. fuscus in Perija. Together, these concordant lines of evidence demonstrate that P. fuscus does not occur in Colombia. Our findings support its removal from national bird lists and conservation assessments and highlight how integrated, multi-evidence reassessments of historical records strengthen ornithological baselines, improve biogeographic inference and ensure that conservation priorities rest on verifiable evidence.

Temperature fluctuations across space and time create a multidimensional thermal landscape within which organisms are exposed to local climates while conducting their daily activities. Tropical species are considered to be particularly sensitive to climate change, with narrow thermal safety margins - the buffer between operative and lethal temperatures. In tropical rainforests, however, species can hypothetically mediate thermal exposure via activity over two local thermal dimensions: vertical (ground-canopy) and temporal (day-night). Such spatiotemporal flexibility could protect species from elevated temperatures and improve thermal safety margins, but this mechanism has not been previously investigated. We test this hypothesis using rainforest ants at a warm lowland and cool upland site (100, 1200 m a.s.l.) in the Australian Wet Tropics. At lowland and upland sites, we quantified microclimate, foraging activity, community composition, and thermal ecology of ants across vertical and temporal dimensions. To assess spatiotemporal flexibility as a climate change mitigation strategy, we calculated thermal safety margins (TSM) as the difference between a species upper thermal limit (CTmax) and mean activity temperature (Te). For each species in each of their spatiotemporal niches (ground-arboreal-day-night) we test whether shifting activity to cooler niches increases TSM using the hottest niches (arboreal and/or daytime) as a baseline. At both lowland and upland sites, ant species were highly stratified vertically, but the large majority (77 - 87.5%) were active both day and night, indicating widespread temporal generalisation. Shifting activity to cooler parts of the thermal landscape substantially improved TSMs: in the lowlands, species with arboreal diurnal foraging increased their TSM by an average of 4.4 {degrees}C ({+/-} 1.7 SE) by shifting to the ground and 6.7 {degrees}C ({+/-} 1.63 SE) by shifting to nocturnal foraging. Improvements were more modest in the uplands: arboreal diurnal foragers increased TSM by 2.1 {degrees}C ({+/-} 2.07 SE) and 2 {degrees}C ({+/-} 0.28 SE) for ground and nocturnal shifts respectively. We therefore demonstrate that foraging niche flexibility is an important climate-change mitigation trait and is most beneficial in the lowlands. Lowland diurnal canopy specialists, however, are most at risk. This represents a large proportion of tropical rainforest biodiversity, supporting previous hypotheses of lowland biotic attrition under climate change.

Astyanax Baird & Girard, 1854 is a widely distributed and species-rich genus of Acestrorhamphidae, whose abundant populations in Neotropical basins play a crucial ecological role at the trophic level. Taxonomic uncertainties persist within the genus, as seen in Astyanax sp. (formerly designated as A. fasciatus) from the Magdalena basin in Colombia. Concerns about its genetic status are heightened due to ecological threats posed by hydroelectric dams, from habitat loss to river connectivity. We isolated and characterized 17 microsatellite loci to assess the population genetics of this species in a broad sample from the middle and lower sections of the Cauca River, now interrupted by the Ituango dam. Furthermore, a multidisciplinary approach integrating phylogenetic analyses of mitochondrial (COI) and nuclear (rag2) markers with geometric morphometric analyses was employed to evaluate potential cryptic diversity within Astyanax sp. Microsatellites revealed two genetic groups in the studied area, strongly supported as distinct lineages by phylogenetic analyses. Unexpectedly, one of these lineages of Astyanax sp. was recovered in an unresolved clade with samples of A. microlepis and allopatric samples of A. viejita from the Maracaibo Lake basin. Each genetic group showed high genetic diversity, but also evidence of recent bottleneck events and significant-high values of inbreeding. Morphometric analyses provided evidence of significant phenotypic differentiation among A. microlepis, Astyanax sp. 1 (Asp1), and Astyanax sp. 2 (Asp2). Morphological patterns ranged from the robust profile of A. microlepis to the streamlined shape of Astyanax sp. 2 (Asp2), with Astyanax sp. 1 (Asp1) displaying intermediate traits and localized differences in head length and fin placement. Statistical support from permutation tests and a high overall classification accuracy (95.65%) underscore the existence of distinct morphospecies, suggesting that phenotypic differentiation is well-established, despite the complex evolutionary history of the group. This study suggests the presence of cryptic diversity within Astyanax sp. and provides valuable genetic information for the conservation and management of their populations in the Magdalena basin.

1) BackgroundUnderstanding how caterpillar communities vary within tree canopies is key to interpreting forest trophic dynamics and responses to environmental change, yet such variation remains poorly quantified due to the challenges of sampling in three dimensions. 2) AimsWe quantified within-canopy heterogeneity in caterpillar densities, diversity, and herbivory and explored relationships with host tree phenology and commonly used ground-based monitoring approaches. 3) MethodsUsing direct canopy access, we sampled branches from lower, middle, and upper canopy strata of 34 mature pedunculate oaks (Quercus robur) in Wytham Woods, UK, during the spring abundance peak over three consecutive years (2023-2025). We tested for vertical stratification in caterpillar community metrics, examined patterns in early instar distributions at emergence, assessed associations with host tree phenology across spatiotemporal scales, and evaluated how well ground-based methods (water and frass traps) reflect canopy communities. 4) ResultsVertical stratification was modest but varied among years: densities and species richness increased with canopy height in 2023, decreased in 2024, and were uniformly low across strata in 2025. Although within-crown budburst timing varied systematically, with upper branches bursting approximately two days earlier than lower branches, tree phenology did not explain within- or between-year variation in caterpillar communities. Frass trap data correlated moderately well with canopy caterpillar densities, whereas water traps showed weaker and less consistent relationships, reflecting behavioural and methodological biases. 5) ConclusionsCaterpillar communities showed no consistent patterns of vertical stratification across years, instead they are shaped more strongly by inter-annual and tree-level variation. Integrating targeted canopy sampling with scalable ground-based proxies could greatly improve monitoring of arboreal Lepidoptera and inform studies of trophic synchrony and wood-land resilience under environmental change.