Biotropica最新文献

The impact of land use changes on pollinator diversity can vary depending on factors such as the size of remaining natural habitat patches, the type and intensity of anthropogenic activities, and the functional composition of pollinator communities. This understanding is particularly crucial for mangrove ecosystems, which are critically endangered by human activities and prioritized in global conservation strategies. This study investigates how anthropization affects mangrove pollinator diversity by examining how pollinators with different functional traits respond to variations in mangrove patch size and anthropogenic changes in the surrounding landscape matrix. We found that overall pollinator abundance, richness, and diversity increased in smaller mangrove patches, potentially helping to mitigate negative effects such as inbreeding and genetic drift—common in naturally patchy and isolated mangrove populations. However, these pollinator metrics declined with increasing landscape anthropization, with notably lower values in urbanized landscapes compared to agricultural ones, despite the smaller patch sizes in more anthropized settings. This negative trend was consistent across pollinators with varying traits, though the magnitude of the effect differed among pollinator groups. Ground-nesting and exposed-nesting pollinators were most influenced by patch size, while lepidopterans and wasps, as well as species with either very small or large body sizes, solitary behavior, and nesting in exposed sites or cavities, were most affected by landscape anthropization. Conservation and management efforts should prioritize habitat provisioning for these most impacted groups to support mangrove ecosystem resilience.

Ethical practice is at the core of scientific practice, notably in the tropics where conservation is confronted with diverse ecological systems, social contexts, and histories of injustice. The Association for Tropical Biology and Conservation (ATBC) recognizes the importance of ethical standards for supporting a scientifically robust, inclusive, and responsible global research and conservation community. Members of ATBC are generally engaged in research and cooperation spanning cultures, disciplines, and frontiers. This reality calls for more than technical proficiency—it requires ethics of shared respect, responsibility, and care. As such, the ATBC Diversity, Equity, and Inclusion (DEI) committee has developed a Code of Ethics to publicly share the core values and guiding principles that shape the ethical and professional responsibilities of our organization's members. The DEI committee aims to foster diversity and inclusion in the ATBC community, contributing to creative and innovative thinking, and allowing for diverse solutions and better science. The Code of Ethics articulates broader ethical commitments and serves as a foundation for ethical decision-making in research, conservation, outreach, and professional conduct. It differs from a Code of Conduct, which focuses on specific behavioral expectations and enforcement mechanisms for professional interactions, including at conferences and society events. By adopting this Code of Ethics, ATBC commits to maintaining a professional environment that supports diversity, respects local and Indigenous communities, upholds scientific integrity, and advances biodiversity conservation as a shared responsibility. This document represents the values and voices of an inclusive group committed to reshaping the way tropical biology is practiced and served. We view these codified ethics as an opportunity to form deeper trust, heal harm, and achieve fairer and better conservation outcomes. Through this Code, ATBC reaffirms our commitment to promoting ethical leadership and accountability within and beyond our organization.

Understanding insectivorous bat diversity and activity is crucial for conservation efforts, particularly in under-researched regions like sub-tropical savannas. Our study assessed bat species richness and seasonal activity (i.e., number of passes) in MalaMala Game Reserve, located within the south-western region of the Greater Kruger National Park (KNP), South Africa, a hitherto unsampled site. We conducted acoustic monitoring using ultrasonic detectors over two distinct seasons: the wet season (January to March) and the dry season (June to August) in 2022. Our findings revealed 16 species from six families, representing 40% of the bat species known in KNP. The Molossidae family was the most dominant, followed by Vespertilionidae, while the Hipposideridae family recorded the fewest calls, likely due to their high-frequency echolocation calls, which attenuate rapidly, or possibly because these bats were less active in our study area, or a combination of both factors. Seasonal variations in bat activity were observed, with significantly higher activity during the wet season, likely due to increased insect abundance and reduced thermoregulatory costs. By targeting a previously unsurveyed region and incorporating seasonal comparisons, our study addresses a critical spatial and temporal knowledge gap and provides a valuable foundation for the development of long-term, standardized bat monitoring across the Greater KNP landscape.

Habitat modification, including global climate change, deforestation, and urbanization, poses significant challenges for species. For organisms that can persist and thrive in altered landscapes, new habitat structures may lead to niche expansion and phenotypical changes. Here, we investigated the variation in morphology and thermal physiology between natural and neonative (urban) populations of Gymnophthalmus underwoodi Grant, 1958, a parthenogenetic lizard found in Amazonia, and forecasted its current and future distribution under climate change scenarios. We compared morphological and thermal traits and assessed urban environments as a potentially stressful habitat using asymmetry indexes. Additionally, we utilized a hybrid species distribution model to infer potential dispersion routes and changes in the species' distribution until 2100 under different climate change scenarios. We found that the neonative population demonstrates enhanced sprint performance compared to the native population as a result of larger hindfeet and forearms of individuals. The distribution model indicates a strong association of the species with open areas near rivers and cities, which may facilitate individuals' dispersion across southern Amazonia. Additionally, the species shows low risks of local extinction and a degree of tolerance to predicted future climates even in extreme scenarios, with distribution ranges inferred to increase over open areas within Amazonia. Our study represents one example in which an Amazonian thermoregulator lizard species may actually benefit from anthropogenic environmental changes, highlighting landscape modification as an important factor in the dispersion of neonative species.

African elephants (Loxodonta africana), in conjunction with the community of browser species, exert substantial top-down control over the woody vegetation in savannas by utilizing large amounts of plant biomass, as well as through non-consumptive effects. However, how much browsers affect the pattern of proportional growth between different tree components remains understudied. Using vegetation data collected in 2000–2001 and 2019 for more than 3500 trees inside and outside Madikwe Game Reserve, South Africa, we determined the long-term effects of an increasing elephant population, in conjunction with the community of meso-browsers, on structural relationships in 13 tree species. The number of trees utilized by elephants increased between 2000 and 2019, but individual trees were not more intensively utilized. After almost two decades of use by elephants, we observed a reduction in the logged initial growth rate of the structural relationship between tree height and stem diameter, without modification of the asymptotic change in growth rate. Despite species-specific variability, tree height was overall reduced for a given stem diameter. Canopy area, as well as its structural relationship with stem diameter, remained mostly stable. We suggest that elephants are responsible for hedging by reducing tree height. Together with impala (Aepyceros melampus), the dominant species in this meso-browser community, they could stimulate regrowth by browsing the canopy of the vegetation maintained in the browsing trap. Our study emphasizes the necessity of long-term, species-specific studies to improve our understanding of how the browser community, and elephants in particular, affect structural relationships in trees.

Agriculture is one of the major drivers of forest loss and fragmentation in tropical regions. Although typically associated with biodiversity loss, agricultural-forest mosaics are increasingly recognized as important targets for conservation as they can support significant bird diversity. This requires understanding how birds respond to habitat amount, quality, and configuration and using this to inform management strategies. Here, we investigated the effects of local and landscape variables at different spatial scales on bird species richness and abundance by conducting 131 point count surveys across forest and matrix habitats in six sites in Northeastern Luzon, Philippines. We found varying significance and direction of community responses to local and landscape factors across different functional groups based on diet and habitat dependency, showing that management interventions must be implemented with clear targets. Overall bird abundance increased with canopy openness, while richness did not show a significant response. In comparison, functional groups exhibited stronger responses. Forest dependent species responded positively to forest area, edge density, and tree species richness. However, several forest species known to inhabit the region were notably absent from our study, suggesting that historical anthropogenic disturbances may have led to their extirpation in the fragmented landscapes. Responses also varied in strength with the spatial scale at which the landscape metric was considered. Therefore, habitat management needs to be tailored to the species targets and spatial scales relevant for conservation.

Belowground resources are key determinants of seedling growth and survival in tropical forests. Nutrients and light may limit plant growth the most in tropical wet forests, whereas water may limit plant growth more in tropical dry forests. Nitrogen (N)-fixing species play an important role in the nitrogen and carbon cycles across tropical dry forests. However, studies investigating the joint effects of water and nutrients on the physiology and performance of N-fixing species are scarce. We implemented a full factorial shade house experiment that manipulated water and nutrients (NPK 20:20:20 and complete micronutrients) using eight tree species representing N-fixing and non-fixing tree species in the tropical dry forest of Costa Rica to determine: (1) How plant responses to water and nutrient availability vary between N-fixing and non-fixing tree species?; and (2) How nutrient and/or water availability influences seedling water- and nutrient-use traits? We found that growth and physiological responses to water and nutrient addition depended directly on the capacity of species to fix atmospheric N₂. N-fixing species responded more strongly to nutrient addition, accumulating 67% more total biomass on average (approximately double that of non-fixing taxa) and increasing average height growth rate by 41%. N-fixing species accumulated more biomass without compromising water-use efficiency, taking full advantage of the increased nutrient availability. Interestingly, results from our experiment show that increased water availability rarely influenced tropical dry forest seedling performance, whereas nutrient availability had a strong effect on biomass and growth. Overall, our results highlight the ability of N-fixing seedlings to take advantage of local soil resource heterogeneity, which may help to explain the dominance of N-fixing trees in tropical dry forests.