ABSTRACT Urbanization is a major driver of biodiversity loss in Southeast Asia, yet its impacts on insect communities remain poorly understood. To address this knowledge gap, we analyzed dung beetle diversity, community composition, and beta diversity across an urbanization gradient from forested areas to managed urban parks in Singapore, a Southeast Asian city. To comprehensively assess the dung beetle communities, we deployed flight interception traps and pitfall traps with varying bait types at 12 sites across the gradient. We found a decline in dung beetle richness and diversity, with changes in community composition and high species turnover with increasing urbanization. Forest‐restricted species, including the ecologically important large nocturnal tunneller, Catharsius cf. renaudpauliani and Singapore's only rolling species, Paragymnopleurus maurus , were found in less urbanized sites, while disturbance‐tolerant species predominated in more urbanized sites. Flight interception traps and human dung‐baited pitfall traps captured distinct dung beetle assemblages, highlighting their complementary value. Importantly, our findings demonstrate that Singapore's remaining forests are vital in sustaining populations of forest‐associated dung beetles and the ecological functions they provide. This study establishes a useful baseline for monitoring the future impacts of urbanization and the effectiveness of Singapore's ongoing greening efforts and naturalizing of urban areas.
ABSTRACT Urban flora is essential for maintaining biodiversity in urban areas, but there is still a knowledge gap, especially in tropical metropolises. Our hypothesis is that there is a dominance of exotic species used in the landscaping of squares, which promotes biotic homogenization, driven by cultural and aesthetic preferences. We believe that larger and older squares have less dominance and greater species diversity. This study investigated the composition, diversity, and representativeness of Amazonian flora across 35 public squares in Manaus, Central Amazonia. We recorded all specimens with a diameter at breast height (DBH) ≥ 5 cm. We recorded 1218 individuals from 88 species and 31 families. Species origin was classified by biogeographic region, with only Amazonian taxa considered native. Exotic species predominated (61.4%). Notably, 15 exotic species with invasive potential were identified, posing significant risks to local biodiversity. We tested the influence of square area and age on community structure. Area was the sole significant predictor of richness, whereas larger and older squares exhibited higher dominance by a few species, such as Mangifera indica (mango) and Moquilea tomentosa (oitizeiro). Age was the only significant negative predictor of alpha diversity. Beta diversity was not influenced by any predictor, indicating a highly homogenized species pool. Urgent management actions are needed that consider both individual squares and the broader landscape to gradually replace exotic and invasive species with native Amazonian species while aligning with the preferences of local residents, thereby restoring ecological functions and enhancing the conservation of urban forests.
ABSTRACT Mistletoe species depend on viscid seeds landing on suitable branches for parasitism, often requiring a limited set of seed dispersers. In Madagascar's southeastern rainforests, our study revealed a surprisingly diverse array of birds consuming mistletoe fruits, but with two small nocturnal lemur species as the major contributors to fruit removal.
ABSTRACT Seed traits offer valuable insights into colonization strategies under climatic unpredictability. In seasonally dry tropical forests, such traits help explain species adaptations to water availability, which is critical for effective restoration. This study analyzed seeds from 22 native species in a Brazilian dry forest to evaluate whether trait‐based approaches can guide the selection of germination pre‐treatments for restoration purposes. Laboratory experiments using 400 seeds per species tested the effects of mechanical, chemical, and thermal scarification on germination performance. We used generalized linear models to evaluate treatment effects on germination for each species and to test how seed size and water content predict dormancy, while generalized linear mixed models tested whether these seed traits influence the efficacy of pre‐treatments. Seed sizes ranged from 5.5 to 2483.2 mg/seed −1 , with water content between 4.8% and 16.3%. Nine species exhibited physical dormancy, while thirteen lacked physical dormancy. Germination percentage increased with seed size following seed coat scarification. Small seeds germinated fast and synchronously in response to mechanical and chemical treatments, whereas larger seeds showed slow and non‐synchronous germination. These patterns suggest that seed size reflects germination strategies and can inform the selection of effective pre‐treatments. Trait‐based approaches may enhance restoration outcomes by accelerating germination of stored seeds. Incorporating a range of seed sizes can support varied regeneration strategies, with non‐synchronous germination helping species cope with rainfall unpredictability and optimize establishment during favorable conditions.
ABSTRACT Anuran vocalizations are crucial for essential behaviors such as reproduction and territoriality. While advertisement calls are extensively documented, subtle courtship calls remain poorly studied. This is worrisome as these calls play an important role in mate selection and reproductive success. Oophaga sylvatica is an ideal study object due to its abundance, disturbance adaptation, and complex reproduction behavior, whose courtship call has never been described. This study provides the first characterization of the O. sylvatica courtship call from northwestern Ecuador and compares it directly to the advertisement call. Utilizing modern bioacoustic analysis to convert sound into quantifiable data, we determined that the courtship call consists of uniform, non‐modulated pulsed notes (mean duration: 0.083 s; dominant frequency: 3239 Hz). The courtship call differs from the advertisement call by having longer notes and narrower frequency, with no change in amplitude. This suggests an adaptation for private, close‐range communication, potentially allowing a male to signal his fitness to a female while minimizing the risk of alerting competitors or predators. These findings provide new insights into the acoustic communication in this species, helping bridge knowledge gaps in its reproductive behavior and discussing the role these calls play in courtship, mate selection, and reproductive success.
ABSTRACT Plants dispersed by visually oriented frugivores may enhance fruit detection through bicolored displays. Using manipulative experiments, I show that higher proportions of unripe fruits, rather than bicolored display alone, increase frugivory. This increased visual contrast amplifies ripe fruit conspicuousness and may serve as an efficient mechanism that enhances dispersal success.
ABSTRACT Poor‐soil Amazonian ecosystems, such as white‐sand ecosystems (WSE, sensu lato), were widespread in the past, reflecting a diverse origin, and have a history of repeated expansion and contraction in response to climate fluctuations and landscape reconfiguration. Although modern climate change outpaces natural processes, we hypothesize that soil nutrient degradation will trigger a cascade of ecosystem reconfigurations, favoring the eventual expansion of WSE‐like habitats long into the future. This expansion may be a nuanced aspect of the broader process of Amazon degradation. Long‐term monitoring and field experiments remain necessary to test these predictions regarding the “once and future” Amazon Forest.
ABSTRACT Global increases in tree mortality from climate change and land‐use are altering forest structures, impacting canopy‐dwelling plants like vascular epiphytes, which depend on host trees (phorophytes). When a phorophyte dies standing, it becomes a snag, the local substrate conditions change and microclimatic exposure may increase, particularly in more canopy‐exposed individuals. The ecological role of snags in supporting epiphyte diversity remains poorly understood. We examined how snags contribute to epiphyte diversity in a dwarf cloud forest in southeastern Brazil. We surveyed 887 phorophytes (778 alive, 109 dead) across 24 plots, recording 127 epiphyte species. Snags, comprising 12% of phorophytes, supported 57% of the total epiphyte richness. Community composition on snags was a nested subset of that on living trees, with no species exclusive to dead phorophytes. Sample‐based rarefaction confirmed that, overall, snags supported significantly lower species richness ( q = 0) and dominant species diversity ( q = 2). Structurally, snags also differed significantly, being shorter, having smaller diameters (DBH), and rougher bark than living trees. While NMDS showed community structure correlated with elevation, height, and bark, this pattern was phorophyte‐species‐dependent. Contrary to the general trend, analysis of the dominant phorophyte Eremanthus erythropappus (“ candeia ”) revealed no significant differences in epiphyte richness ( q = 0) or dominant diversity ( q = 2) between living and dead individuals. Our results suggest snags function as secondary refuges, but their capacity to buffer epiphyte loss could be mediated by host species traits.
ABSTRACT In fragmented landscapes, pollination is key for connectivity within and between plant populations, improving fecundity and genetic diversity. Pollination research has largely focused on crops and understory plants, while trees, the key components of tropical forests, have received much less attention. In this study, we used colored sticky traps to investigate the pollination biology of a large‐seeded tree, Antiaris toxicaria Lesch. (Moraceae), across six forest fragments within a 10‐km radius in Xishuangbanna, southwest China. We explored how forest fragmentation shapes pollinator assemblages and potential pollen mass flow patterns, and how these patterns varied across different pollinator groups. We collected 1137 morphospecies that were confirmed to carry pollen grains of A. toxicaria . Dipterans and hymenopterans were the most species‐rich and carried the greatest number of pollen grains. Pollinator richness and abundance showed hump‐shaped relationships with fragment size, potentially due to edge effects in the medium‐sized fragments and dilution effects in the largest fragments. In contrast, pollen mass flow increased with increasing fragment size, except in the smallest fragment, where we found a substantial increase likely due to the high density of focal trees. These results suggest that habitat fragmentation only negatively impacted potential pollination processes in small fragments through reduced pollinator diversity. Protecting and improving connectivity among medium to large fragments may help sustain pollination processes in fragmented landscapes. Future research on pollinator behavior and whether pollen is successfully dispersed among fragments would provide additional insights as to whether the populations of large‐seeded plants retain viability in small to medium‐sized fragments.
ABSTRACT Cloud lines, defined as persistent bands of stratus clouds along elevational gradients, create abrupt shifts in temperature, humidity, and visibility that can profoundly influence biodiversity. We investigated the effects of cloud lines on avian species richness and community structure along a one‐kilometer elevational gradient (480–1420 m) located in the sub‐montane zone of Sri Lanka—a tropical continental island in the northern Indian Ocean. Standardized avian surveys were conducted over 1 year using visual, acoustic, mist‐net, and camera‐trap methods across ten permanently marked transects situated along contour lines spanning the gradient. The elevation of the cloud line was recorded using visibility charts, and environmental covariates were measured in each transect. Species richness declined significantly with increasing distance from the cloud line (Pearson r = −0.22, p = 0.05). In negative binomial models controlling for elevation, light intensity, and habitat complexity, the cloud line emerged as a significant predictor of avian richness (ΔAIC > 18). Among the 96 species recorded—including 23 endemics—those with broader elevational ranges exhibited a stronger association with the cloud line ( p < 0.001). The distribution of birds was non‐random with respect to cloud line elevation (Chi‐square: p < 0.001), particularly at lower elevations. These findings underscore critical conservation concerns, as climate‐driven shifts in cloud line position may disproportionately affect biodiversity confined to cloud‐associated habitats such as tropical cloud forests.
ABSTRACT Elevation gradients are powerful drivers of changes in species composition, richness, and functional traits. We studied bee communities at 14 sites across a 3000 m elevational gradient in the Colombian Andes. We measured morphological traits on all individuals (body size, relative leg length, relative wing length) and used assemblage data to measure composition, richness, evenness, Simpson's diversity, and trait diversity. We found that assemblage composition turned over rapidly with sites greater than 1000 m in elevation apart, sharing less than 1% of species. Bee richness decreased with elevation, with low elevation sites (< 2000 m) having an average of 26 species and high elevation sites (> 3000 m) averaging 3.4 species. Simpson's diversity and trait diversity showed similar patterns, while evenness did not change with elevation. Assemblage trait means also changed with elevation, as high elevation communities had larger body sizes and shorter wings and legs. These results fit with predictions from both Bergmann's and Allen's rules, suggesting thermoregulation may be a factor driving changes at high elevation. This is the first study of its kind in the Andes and adds to a large number of bee assemblage studies that also show decreases in bee diversity with elevation, indicating that it is a near‐universal pattern. However, results from the small number of existing studies on bee morphological trait changes with elevation are highly variable, suggesting these changes have a variety of mechanisms driving them and are likely context dependent.
ABSTRACT Drought tolerance inferred from functional traits has been shown to explain tree species distributions with respect to rainfall and topography in dry tropical forests, but the extent to which drought tolerance may influence species distributions in wet tropical forests remains unclear. We measured the leaf water potential at turgor loss point ( Ψ TLP ), a leaf hydraulic trait associated with drought tolerance, and representing the leaf water potential threshold for wilting, for 58 abundant tree species in an aseasonal lowland tropical forest in Peninsular Malaysia. We tested whether tree spatial distribution in relation to topographic soil moisture levels (i.e., Topographic Wetness Index; TWI) within a 50‐ha forest plot (the ForestGEO Pasoh plot) was related to Ψ TLP . We found that 76% of species showed spatial associations with TWI within the 50‐ha plot. Species' spatial association with soil moisture levels was statistically independent of Ψ TLP . Even in wet tropical forests defined by no distinct dry season, soil moisture associated with topography exerts a strong influence on tree species distributions, but topographic distributions are not associated with one of the components of species' drought tolerance as quantified with Ψ TLP . These findings highlight the sensitivity of tropical forests to variation in soil water levels, regardless of species' capacity to maintain physiological function under drier conditions, leading to a potential shift in community assemblages and structures following extreme events.
ABSTRACT Large omnivorous mammals can play multifunctional roles in tropical ecosystems by linking trophic processes with plant regeneration dynamics, yet their contributions remain poorly understood in seasonally dry forests. We investigated seasonal variation in sloth bear ( Melursus ursinus ) diet and their potential role as seed dispersers in a semiarid deciduous forest of the Aravalli mountains in western India. Diet was assessed through scat analysis in the winter and summer seasons from November 2020 to October 2021, and seed dispersal effectiveness was evaluated using germination and survival experiments on seeds recovered from scats and those collected directly from plants. Sloth bear diet exhibited pronounced seasonal shifts, with fruits dominating winter diets and insects constituting a larger proportion during summer. Fruit consumption was selective and not consistently proportional to availability, indicating preferential foraging. Seeds of six plant species remained viable after gut passage, with germination success varying among species. For four species, post‐germination survival of seedlings from scat seeds and from plant‐collected seeds was not significantly different, while seedlings from plant‐collected seeds of Grewia flavescens and from scat seeds of Diospyros melanoxylon survived better. Germination of the nonnative invasive shrub Lantana camara occurred only from scat‐derived seeds. Our findings demonstrate that sloth bears function as selective seed dispersers, including enhancing the germination success of an invasive shrub in dry deciduous forests. Our findings highlight the importance of increasing focus on how large omnivores influence plant regeneration thereby potentially affecting landscape‐level vegetation dynamics in tropical seasonal ecosystems.
ABSTRACT We report tail luring and rain‐harvesting in two species of Bothrops pitvipers from the Atlantic Forest of Brazil. Our observations challenge the widely held views that tail luring is largely restricted to juvenile pitvipers, and that rain‐harvesting is an adaptation evolved by vipers to cope with life in water‐limited environments.
ABSTRACT Species distributions are shaped by complex biotic and abiotic interactions, which are often not fully understood. We investigated the ecological basis of co‐occurrence and distribution of four partially sympatric and allopatric cryptic mouse lemur species ( Microcebus spp.) in the Ambatosoa and Analanjirofo region of northeastern Madagascar. Using structural habitat characteristics, adaptability to habitat degradation, bioclimatic niches, and morphology (incl. body mass variability), we estimated n ‐dimensional hypervolumes of niche sizes and overlaps. M. jonahi and M. simmonsi were found almost equally often in forest‐ and fallow‐derived habitats (52% and 58%, respectively), while M. lehilahytsara predominantly occupied fallow habitats (71%) that result from shifting cultivation practice. M. lehilahytsara exhibited the largest niche and range size, followed by M. jonahi and M . simmonsi . M . jonahi and M . simmonsi displayed significant fat deposition before the austral winter, indicating heterothermy as an adaptation to unpredictable environmental conditions. These two species were only found in allopatry, likely due to competition for critical resources like sleeping sites. The smaller M . lehilahytsara co‐occurred with M . jonahi and M . macarthurii potentially by adjusting its niche to avoid competition with these larger‐bodied species. We hypothesize that heterothermy allowed M . jonahi and M . simmonsi to persist in lowland habitats during cold phases of the Pleistocene but that it did not promote co‐occurrence. In contrast, M . lehilahytsara may have lost lowland distributions due to a lower capacity to deposit fat. Our findings require further testing but provide a plausible explanation for a complex distributional pattern of sympatric and allopatric occurrences in northeastern Madagascar.
ABSTRACT Although street trees may ameliorate the negative impacts of urbanization on biodiversity and improve cities' sustainability standards, they have been globally used with poor ecological criteria. In many cities, there is a notable lack of standardized assessments of street afforestation, particularly those outside major urban centers. Here we evaluate the distribution, richness, and species composition of street trees in 10 semi‐arid Brazilian cities, analyzing the proportion of native and non‐native species and the potential of these urban areas to support biodiversity. In each city, we sampled four 300‐m linear transects of woody vegetation along public roads and conducted a satellite‐based supervised classification to examine the relationship between species richness and the percentage of local impervious surface. A total of 1381 trees of 69 species were identified. About 80% of the individuals and 52% of the species were non‐native. More concerning, approximately 60% of the individuals belonged to exotic invasive species; the Indian Neem alone, Azadirachta indica , accounted for 700 individuals. As expected, the increase in impervious surface cover negatively affected the native species richness. Five cities were classified as antagonistic for biodiversity due to the high proportion and dominance of non‐native species. These findings reveal a concerning bias towards exotic invasive tree species in the studied Brazilian cities, potentially causing negative effects on the remaining urban biota. We strongly recommend that street afforestation strategies remove the invasive species from their portfolio, reduce the use of exotic non‐invasive ones, and increase the adoption of native trees as much as possible.
ABSTRACT Inter‐reproductive complexes, also known as hybrid zones, are sites where no apparent barriers exist to gene flow between two species or populations. In systems where domesticated plant species coexist with their wild relatives, such complexes can facilitate the generation of hybrid offspring, which may serve as genetic bridges for the incorporation of domesticated genes into wild populations. This gene flow may introduce non‐adaptive alleles, potentially compromise the adaptive capacity of wild populations, and threaten their long‐term survival. In tropical regions of Mexico, backyard gardens provide an ideal setting to study these dynamics, as they promote genetic interactions between domesticated and wild individuals. In this study, we used a population genomics approach to assess the genetic structure, genetic diversity, and gene flow among wild, hybrid, and domesticated Carica papaya within four inter‐reproductive complexes located in Mayan communities of the Yucatan Peninsula, Mexico. We analyzed 5647 SNP markers from 180 individuals. Our results revealed three distinct genetic groups (wild, hybrid, and domesticated), with the highest diversity found in the wild populations ( H E = 0.207), the lowest in the domesticated populations ( H E = 0.136), and an intermediate genetic diversity in the hybrid group ( H E = 0.202). Gene flow analysis showed that the hybrid group exhibited the highest migration rate into the wild group ( m = 0.045). These findings highlight the potential for gene flow to alter the genetic structure and diversity of papaya populations in inter‐reproductive complexes in the Yucatan Peninsula, part of the origin center of the species.
The practice, geography and nature of tropical ecology have shifted substantially over past decades, but existing syntheses rarely resolve long-term, pantropical patterns across biomes. This gap is partly due to the challenge of analyzing vast and rapidly growing literature. The advance of large language models enables such analysis for the first time. We analyzed over 170,000 tropical ecology publications (1960-2023) to quantify long-term research trends across five major biomes, identify the most studied countries and leading contributors (based on first-author affiliations), and evaluate their relationships with national socio-economic indicators. Using GPT-4o mini to extract contextual location and biome data, we found that research output has increased across all biomes, but the rate of increase has been highest for tropical forests and lowest for grassy biomes, resulting in a growing dominance of forests and a relative decline of grassy ecosystems. Tropical coastal and freshwater biomes have seen modest relative increases, while oceanic biomes remain stable in relative effort. This relative decline is particularly concerning for Africa, where savannas cover similar to 70% of tropical land. Since 2010, 73% of tropical ecology papers have come from research hosted in ten tropical countries, led by Brazil (25%). China, India, Mexico, Indonesia and Malaysia are slowly rising to be powerhouses of tropical ecology. Conversely, early research featured broader African representation. This geographical disparity is more closely tied to socio-economic capacity than biome extent. Our analysis highlights both this encouraging shift and the remaining disparities, underscoring the need to strengthen research capacity in underrepresented tropical regions.
Tropical forests play a crucial role in global carbon cycling but face increasing stress from rising temperatures and atmospheric drought (vapor pressure deficit, VPD). While most studies assess photosynthetic performance at fixed time points, short-term diurnal variation in photosynthetic parameters remains underexplored. We examined how the optimum temperature of photosynthesis, photosynthetic capacity, electron transport rate, and thermal tolerance vary throughout the day in tropical tree species Calophyllum inophyllum. Morning and afternoon measurements were conducted using gas exchange (FAsTeR and Dynamic A-Ci methods) and chlorophyll fluorescence. Photosynthetic capacity declined significantly in the afternoon, with lower light-saturated photosynthesis rates, A max (-29%), maximum carboxylation rate, Vcmax (-32%), and triose-phosphate utilization rate, TPU (-21%) than in the morning, despite consistent measurement conditions. These declines were not driven by stomatal or mesophyll conductance, suggesting biochemical downregulation. In contrast, thermal tolerance metrics (T 50 and T crit) remained stable between morning and afternoon, indicating decoupling between heat tolerance and metabolic performance. Our findings support a physiological strategy in C. inophyllum that prioritizes morning carbon gain and modulates photosynthetic efficiency throughout the day without compromising heat tolerance. This dynamic regulation underscores the need to account for diurnal variation and temperature-sensitive constraints into models of tropical forest function. Relying on photosynthetic capacity estimated under favorable morning conditions risks overestimating carbon uptake under future climate scenarios.
Climate change is driving increases in the frequency and intensity of extreme climatic events locally and globally. For instance, severe frost events seem to be happening on average every 5 years, rather than 7 years, as previously reported in the southern limit of the Cerrado, a Neotropical savanna. Although frost effects on leaf and branch damage are relatively well studied, the effects of frost on fleshy fruit production in natural vegetation and its potential effects on frugivorous animals are largely unknown. We conducted this study in the Cerrado, where severe frost events allowed us to compare fruit production and frugivorous bird abundances before and after the disturbance, and between sites affected and non-affected by frost. Frosts decreased fleshy fruit production and the number of plant individuals bearing fruits but had no clear effects on species richness and abundance of frugivorous birds. However, bird abundances increased locally with fruit production only in sites affected by frost. Our results suggest that frost events in Cerrado reduce fruit availability, indirectly impacting frugivorous bird abundances. These findings suggest that frosts may trigger cascading effects on seed dispersal and plant recruitment, and the broader frugivore community, especially under future scenarios of more frequent and extreme climatic events. As mudan & ccedil;as clim & aacute;ticas est & atilde;o desencadeando aumentos locais e globais na frequ & ecirc;ncia e intensidade de eventos clim & aacute;ticos extremos. Por exemplo, eventos severos de geada parecem estar ocorrendo em m & eacute;dia a cada cinco anos, ao inv & eacute;s de a cada 7 anos, no limite sul do Cerrado, uma savana neotropical. Embora os efeitos da geada sobre folhas e ramos sejam relativamente bem estudados, os efeitos da geada sobre a produ & ccedil;& atilde;o de frutos carnosos em ecossistemas naturais e seus potenciais impactos sobre animais frug & iacute;voros permanecem amplamente desconhecidos. Nosso estudo foi conduzido no Cerrado, onde eventos severos de geada nos permitiram comparar a produ & ccedil;& atilde;o de frutos e a abund & acirc;ncia de aves frug & iacute;voras antes e ap & oacute;s a perturba & ccedil;& atilde;o, e entre & aacute;reas afetadas e n & atilde;o afetadas pela geada. As geadas reduziram a produ & ccedil;& atilde;o de frutos carnosos e o n & uacute;mero de indiv & iacute;duos de plantas com frutos, mas n & atilde;o tiveram efeitos claros sobre a riqueza de esp & eacute;cies e a abund & acirc;ncia de aves frug & iacute;voras. No entanto, a abund & acirc;ncia de aves aumentou localmente com a produ & ccedil;& atilde;o de frutos apenas nas & aacute;reas afetadas pela geada. Nossos resultados sugerem que eventos de geada no Cerrado reduzem a disponibilidade de frutos, impactando indiretamente a abund & acirc;ncia de aves frug & iacute;voras. Isso indica que geadas podem desencadear efeitos em cascata sobre a dispers & atilde;o de sementes, o recrutamento de plantas e a comunidade de frug & iacute;voros como um todo, especialmente em cen & aacute;rios futuros de eventos clim & aacute;ticos tornando-se mais frequentes e intensos.
