We document predation and surplus killing of Aglyptodactylus frogs by ring-tailed vontsira (Galidia elegans) during an explosive breeding event in northern Madagascar. The observation shows how synchronized reproduction after a cyclone provides an important feeding opportunity for a predator.
Currently, land conversion for cultivation, livestock raising, and plantations (i.e., land-use change) is a significant threat to global biodiversity, especially in tropical forests. Hence, this study analyzes the differences in taxonomic and functional alpha and beta diversities of amphibians and reptiles among three land-uses (montane cloud forest, rainforest, and pastures) in central Mexico. Hill numbers were used to calculate both alpha taxonomic and functional diversity, while beta taxonomic and functional diversity were calculated considering their turnover and nestedness components; in addition, we identify functional groups for each taxa. Amphibian taxonomic and functional diversity was similar among land-uses, whereas reptile taxonomic and functional diversity was higher in forests than in pastures. We found high beta taxonomic diversity of herpetofauna among all land-uses, where turnover was the predominant component. However, beta functional diversity was low and functional nestedness predominated in most cases. Likewise, the abundance of reptile and amphibian functional groups differed among land-use types. We suggest that species ecological resilience, homogeneous species distribution, and environmental filters may explain these taxonomic and functional diversity patterns of herpetofauna. Finally, researchers are encouraged to consistently document and publish morphological, reproductive, behavioral, and ecological data on tropical amphibians and reptiles to support current and future studies on the functional diversity of herpetofauna.
Tropical dry forest regeneration in human-modified landscapes may be more complex than previously proposed, since the remaining forest is permanently exposed to myriad of human disturbances. We examined the regeneration of a Caatinga dry forest in the context of extraction of forest products and livestock production to reveal patterns and potential mechanisms driving forest regeneration in a human-modified landscape. Seed, seedling, and adult assemblages from woody species were sampled across a forest chronosequence and old-growth forest (OGF) stands. Community-level metrics were related to the age of regenerating forest stands, precipitation, and human-chronic disturbances via linear and non-linear statistical models and multivariate analyses. Overall, regenerating and OGF stands exhibited similar stem abundance and species richness across all ontogenetic stages. Little directional changes occurred along forest regeneration, with a negligible role played by forest stand age, precipitation, and chronic human disturbance. Moreover, species exclusively recorded as adults or seeds were mostly dispersed by animals, indicating that several species fail in either dispersing or recruiting due to human disturbances (e.g., defaunation) and harsh environmental conditions. In short, the apparent fast recovery of Caatinga is due to a low diversity and the predominance of species abiotically dispersed and able to resprout, suggesting a human-driven degradation trajectory rather than a natural condition.
Army ants prey mainly on invertebrates, occasionally attacking vertebrates. However, it remains unclear whether these attacks are defensive or for consumption. By testing the diet of Labidus coecus, we show that they can be attracted to vertebrate meat, which may expand the army ants' ecological role, spurring new research.
Red-footed (Chelonoidis carbonarius) and yellow-footed tortoises (C. denticulatus) are highly frugivorous, terrestrial chelonians found throughout the Neotropics. We investigated the role of these tortoises as seed dispersers in plant communities in the northern Brazilian region of the Amazon Basin. We analyzed movement patterns of radio- and thread-tracked individuals, estimated gut retention time of seeds in captive tortoises, and analyzed fecal samples for abundance, diversity, and viability of seeds. Our results show tortoises to be effective seed dispersers: of 113 fecal samples examined, 92% contained seeds of 19 plant species. Seeds of 17 of these species were viable. Fecal clumps averaged 2.2 species (range 0–5) per unit with a median of 102 seeds per sample (range 0–1140). Larger-bodied tortoises dispersed more seeds. Integrating these data through movement simulations revealed that long gut retention times for seeds (10–28 days), combined with mean daily tortoise displacements of 103 m, generate seed shadow curves that peak between 300 m (female tortoises) and 400 m (male tortoises) and extended beyond 1 km from the seed source. This study demonstrates differential disperser effectiveness as a result of tortoise size and differences in movement patterns between sexes.
Natural and seminatural habitats provide important resources for many plant and animal species. The destruction of such habitats might reduce biodiversity and disturb ecosystem functions. Sub-Saharan Africa suffers particularly under the destruction and deterioration of ecosystems due to demographic pressure. In this study, we analyzed ecosystem functions in a small remnant of East African coastal forest and the surrounding anthropogenic landscape. We measured pollination activity, predation, and seed dispersal. For each study plot, we also recorded local habitat conditions, which may also influence ecosystem functions. We found no significant difference between the natural forest and anthropogenic agro-environments for seed dispersal nor pollination. Insect predation showed highest rates inside the forest and decreasing rates in the open agro-environments. Local environmental conditions strongly affected ecosystem functions. For example, flower availability showed positive effects on pollination activity, and the availability of herbs on the ground positively influenced the level of predation. Rather homogenous ecosystems such as eucalyptus plantations and arable land showed lowest levels of ecosystem functions. Here, planting of undergrowth such as herbs and flowers may improve ecosystem functions. Our findings underline that natural forest as well as heterogeneous agro-environments provide a large variety of ecosystem functions, which strongly depend on site-specific microhabitat conditions.
Most plant communities worldwide include exotic plants, which did not evolve with local organisms. The central goal of this study is to test if native organisms expanding their interactions to novel hosts are usually generalists or specialists. Here we studied new associations between hummingbirds, flower mites and Musa velutina (Musaceae), an exotic plant native to northeast India currently invading lowland forests in Costa Rica. Hummingbirds are pollinators, but flower mites feed on nectar without contributing to pollen transfer. Flower mites hitch rides on hummingbird beaks to colonize new flowers. To determine the original diet breadth of hummingbird and flower mite species, we assembled hummingbird and flower mite interactions at La Selva Biological Station. We identified four hummingbird species visiting Musa velutina. DNA barcode analyses identified only one species of flower mite colonizing flowers of M. velutina. All new associations with M. velutina involved generalist hummingbird and flower mite species. Musa velutina displays both male and female flowers. Although flowers of both sexes were equally visited by hummingbirds, mites were 15 times more abundant in male than in female flowers. We hypothesize that this is the result of constant immigration coupled with mite population growth. Only half of the mites hitching rides on hummingbird beaks emigrate to newly opened flowers. Our results show that M. velutina integration to a plant community occurs mainly by establishing interactions with generalists.
Biotropica, the flagship journal of the Association for Tropical Biology and Conservation, is a highly regarded source of original research on the ecology, conservation, and management of all tropical ecosystems, and on the biology and evolution of tropical organisms. We aim for timely, fair, transparent, and constructive reviews and editorial decisions on the 400–500 manuscripts received yearly. We value a geographically diverse Editorial Board with broad expertise in tropical taxa and ecological, evolutionary, and conservation research, reflecting our diverse authorship and readership.
In 2024, we ran our second open call for service on our Editorial Board. This year, we selected seven new Subject Editors from a highly qualified pool (Figure 1). Their expertise includes taxa such as mammals, birds, epiphytes, and micro-organisms, and conceptual areas, such as habitat fragmentation, pollination, frugivory, restoration, and plant–soil interactions. Our new Subject Editors represent a geographically diverse group of institutions in Brazil, India, Mexico, Poland, and the United States. Please join us in welcoming our new Subject Editors and thanking those who are rotating off the Editorial Board, which now comprises 64 members based in 20 countries. The open call for editorial service will be an annual call, so please consider serving on our Editorial Board in the future.
In diverse tropical communities, individuals with more distinct traits typically have lower abundance. In many tropical communities, the most distinct plants with regard to their stoichiometry are metal hyperaccumulators. The Celastrales, Oxalidales, and Malpighiales (COM) clades feature more than 50% of known nickel hyperaccumulators. Metal hyperaccumulation likely incurs high energy costs for physiological processes, potentially reducing competitive ability in nutrient-limited environments. We therefore test if COM species that are increasingly stoichiometrically distinct are also rare, and if these effects depend on soil metal concentrations. We measured leaf element concentration for 283 tree species from ten 0.25 ha plots over ultramafic (metal-rich) and non-ultramafic soils in Sulawesi, Indonesia. We fit a phylogenetic mixed-effects model of abundance with calculated leaf stoichiometric distinctiveness, soil metal concentrations, macronutrient concentrations, pH, and whether species belong to COM clades as further predictors. At all soil metal concentrations, species with more distinct leaf stoichiometry are rare, except for COM species. In tropical forests of Sulawesi, metal accumulation does not have a negative relationship with the abundance of COM species but does with other clades. Metal accumulation reflects a niche axis that impacts the structures of communities across ultramafic and non-ultramafic soils.
Heuglin's Gulls (Larus heuglini) GPS-tracked from Sri Lanka to the Arctic in successive years followed a combination of coastal and overland routes through Eurasia (~8000 km) instead of the shortest maritime (~15,000 km) or shortest transcontinental (6346 km) routes, revealing a novel transcontinental passage for seabirds between the Indian and Arctic Oceans.
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