Biotropica最新文献

Determining the factors affecting the structure of insect herbivore communities is a major challenge in ecology. Previous research demonstrated that plant defenses determine plant-herbivore associations. However, non-defensive variables may also explain why some plant species are associated with more diverse insect herbivore assemblages than others. Neotropical rolled-leaf beetles (Cephaloleia and Chelobasis) complete their life cycle inside the young rolled leaves of their host plants in the order Zingiberales. The diet breadth of each species in this assemblage is particularly well-known at our study site, La Selva Biological Station in Costa Rica. This study focused on the following non-defensive variables: host plant elevational and geographic range size, soil type, habitat, local abundance, plant size, and leaf size. Because plant characteristics among closely related plants are not independent, we analyzed these variables in a phylogenetic context. We detected a positive effect of leaf width on rolled-leaf beetle species richness (explaining 55% of the variation), abundance (28% of the variation and 57% when habitat is included in the model), diversity (37% of the variation), and community structure (6% of the variation, and 21%–26% when taxonomic family is included in the model). Our study demonstrates that Zingiberales leaf width influences positively rolled-leaf beetle species richness, abundance, and diversity. This effect varies among plant families. Our study shows that plant architecture plays an important role in structuring insect herbivore assemblages in Zingiberales. Our results highlight the importance of including variables beyond plant defenses to understand the ecology and evolution of plant-herbivore interactions.

Understanding biodiversity patterns is essential for ecology and conservation. Globally, conservation efforts often prioritize tropical rainforests due to their high species richness. At the regional scale, the same is true in the Greater Annamites ecoregion of Vietnam and Laos, where conservation efforts have largely focused on broadleaf wet evergreen forest, despite the fact that other habitats remain threatened. One such habitat is the coastal dry forest landscape in southern Vietnam, which has received little conservation focus despite the fact that its forested areas have been severely reduced. Nui Chua National Park (NP) in southern Vietnam harbors one of the few remaining sizable areas of dry coastal forest. In this study, we used camera-trap data and a community Royle-Nichols model to explore community structure of ground-dwelling mammal and birds along a complex habitat gradient in Nui Chua NP. We first investigated species associations among three habitat types: dry forest, semi-dry forest, and broadleaf wet evergreen forest. We then used occupancy-based diversity profiles to assess diversity in these three habitats. Overall species diversity tended to be highest in the transitional semi-dry forest ecotone, which supported species from both dry and evergreen forests. Notably, the semi-dry forest also had the highest occupancies for several endemic and threatened species. Our findings highlight the importance of the semi-dry forest for conservation in the broader coastal dry forest landscape. We emphasize the need for fine-scale biodiversity assessments to inform conservation strategies, especially in habitats that may be overlooked by broader-scale conservation strategies.

Seasonally dry tropical forests (SDTFs) experience large spatial and temporal variation in water and light availability. The effect of heterogeneity in these limiting resources on species water use, physiology, and growth is still not well understood. We used a shade-house experiment to manipulate light and water availability and examine plant water uptake, leaf-level physiology, and sapling growth in four co-occurring SDTF species belonging to both evergreen and deciduous plant functional types. Water uptake varied dramatically among species with a fivefold difference in maximum whole-plant transpiration (WPT). While species differed in how WPT, leaf physiology, and growth responded to shade, there were no differences among species, or between evergreen and deciduous functional types, in responses to limited water. Importantly, responses to shade were independent of water availability in all four species. Changes in WPT in response to limited light and water were largely congruent with changes in leaf physiology and growth. However, the magnitude of change in leaf physiology was largely driven by light, while changes in WPT and growth were driven by water availability. Thus, whole-plant water uptake may be a better indicator of plant growth responses in these species. Overall, these results suggest that responses to light and water limitation may be independent of each other, allowing species in SDTFs to explore a wide range of combinations of light and water responses to adapt to heterogeneous light and water niches.

Anthropogenic fire is a worldwide event that affects many ecosystems and organisms. In Southern Brazil, grassland management with fire has been highly employed since the mid-18th century. Although the practice is regulated by federal law (prescribed fire), there is no detailed information about the impacts of this practice on the small, non-volant fauna. We evaluated the effect of fire management on anuran species richness and community composition in Brazilian grassland areas that have adopted this practice for more than 15 years. Our results show that burning practices lead to a reduction of anuran richness. About 37% of the species occur exclusively in sites free of fire. Sites with fire management have low densities of taller grass and shrubs, which could reduce habitat availability for some anuran species. Nestedness and turnover components of beta diversity did not differ within and between treatments, but there was a tendency for a nestedness organization of the community in burned sites, suggesting that sites with fire management are a subsample of sites where fire is absent. Our results pointed out that prescribed fire practices have potentially negative effects on the anuran diversity. These results suggest that the changes in vegetation, in particular percentages of shrub cover, affect habitat suitability for some species. Therefore, anuran communities tend to become less diverse and lack arboreal species where fire occurs.

Abstract in Portuguese is available with online material.

Tropical deforestation is occurring at alarming rates, creating an urgent need for global prioritization of restoration efforts. One potential forest recovery strategy is to boost seed-dispersing animal activity (e.g., fruit-eating bats) to increase seed availability in degraded areas. In this study, we investigated the efficacy of synthetic chemical lures in attracting fruit bats and enhancing seed rain in northeastern Costa Rica. The chemical lures were composed of a few volatile organic compounds commonly found in ripe bat-dispersed fruits. Daily deployment of the chemical lures resulted in a significant increase in the capture of Carollia spp., a key neotropical seed disperser, but no detectable effect on other fruit bats. The 15-day deployment of chemical lures also increased the average of total seeds collected in seed traps. However, the effect of lures explained only a small portion of the total variance in seed rain, highlighting the potential context-dependency of these results. Still, in contrast to the previously studied essential oil-based lures, synthetic lures hold the potential to be applied across a broader spectrum of restoration initiatives due to simplified manufacturing and improved reproducibility. Although additional research is essential to understand the full potential for use in restoration efforts, our study demonstrates the effectiveness of synthetic chemical lures in attracting fruit bats and potentially augmenting seed rain.

Modified landscapes can restrict the movement of organisms, leading to isolation and reduced population viability, particularly for species with extensive home ranges and long-distance travel, such as white-lipped peccaries (WLPs, Tayassu pecari). Previous studies have indicated that forested areas favor WLP herd movements, but the impact of the non-forested areas on their genetic connectivity is unknown. In this study, we used land use and land cover maps and population genetic data to investigate the impact of non-forested matrices on WLP's genetic connectivity in the Pantanal floodplain and surrounding Cerrado plateau of central-west Brazil. We compared isolation-by-distance (IBD), isolation-by-barrier, and isolation-by-resistance models and tested 39 hypotheses within a modeling framework. Finally, we identified the optimal areas for ecological corridors based on the most effective landscape model. Barrier and landscape resistance were more strongly correlated with genetic relatedness than the IBD model. The model that received the most robust support considered only forest as habitat. All other classes formed a matrix that impeded gene flow, including agriculture, grassland, savannah, and paved and unpaved roads. WLP herds living in landscapes with reduced forest cover are more vulnerable to the effects of genetic isolation. To maintain gene flow, conservation programs should prioritize strategies that strengthen connections between habitats, including facilitating wildlife road-crossing structures and creating/restoring ecological corridors to link isolated habitat fragments.

Abstract in Portuguese is available with online material.