Biotropica最新文献

Caves impose restrictive environmental conditions that often promote morphological convergence, especially under permanent darkness. Isopods are successful colonizers of these habitats, yet the processes structuring their biodiversity in hypogean systems remain poorly understood. We tested whether hypogean habitats differ from epigean ones in the standardized effect size of functional richness (SES α) and whether functional dissimilarity is driven by distinct β-components. We assembled a site × species matrix (54 sites) and a species × traits matrix, standardized traits, and estimated n-dimensional probabilistic trait spaces (Gaussian-kernel hypervolumes) using three PCoA axes. Functional α-diversity was measured as hypervolume size, and pairwise β-diversity was partitioned into β_total, β_repl, and β_richl. Null expectations were obtained by randomizing the trait matrix, and SES values were computed for α and β metrics. Communities were classified as epigean (Epi), hypogean with troglobites (Hyp), and hypogean without troglobites (HypWT). SES α ranged from strongly negative to strongly positive, with Epi and HypWT showing slightly higher central tendencies than Hyp, but without significant differences among groups. SES β_repl was significantly lower and SES β_richl significantly higher among groups, indicating reduced functional turnover but amplified richness differences. Trait overdispersion was more frequent in Epi and HypWT sites than in Hyp sites. Taken together, these patterns indicate that isopod communities along the epigean–hypogean gradient are shaped mainly by environmental filtering and an uneven occupation of trait space, rather than simple trait replacement.

Tropical nectarivorous birds should have flexible movement behaviors in response to the spatiotemporal availability of flowers. In the Neotropics, hummingbirds (Trochilidae) have diet breadths constrained by trait-matching with flowers, while nectar-robbing flowerpiercers (Thraupidae) typically drink nectar from holes pierced at the flower's base. Distinct movement patterns for these two bird families would be expected from optimal foraging theory due to differences in dietary specialization and behavioral flexibility, yet little is known about the daily movement patterns of tropical nectarivores. We used fine-resolution tracking data from an automated radio telemetry grid to compare movement patterns between hummingbirds and flowerpiercers in high-Andean mountain ecosystems, and obtained an accumulated total of 435,513 location estimates and 452 tracking days from 22 individuals across six bird species. Our results indicate that hummingbirds exhibit a greater diversity of movement behaviors compared to flowerpiercers, with varying space use and recursion patterns that are characteristic of sedentary, commuting/traplining and exploratory strategies, whereas most species of flowerpiercers were classified as central-place foragers. However, there is substantial variation in daily movement metrics and hierarchical clustering does not necessarily group together bird families, species, nor even individuals as more similar to each other. Flexibility in movement behaviors has seldom been described for neotropical nectarivorous birds in the wild. It emerges as an important trait to adjust behavior to variable local contexts, and may be adaptive for the persistence of pollinators in challenging mountain ecosystems, where weather conditions are harsh and floral resources are seasonal.

We used edible glitter to mark 15,526 fruits of three chiropterochorous plants at 700, 1000, 2000, and 3200 m from a bat roost in Brazil's caatinga. Glitter from all distances was detected at the roost, allowing the identification of specific feeding areas accessed, providing a new approach for zoochory studies.

Urban biodiversity is often studied along urbanization intensity gradients, which can overlook the critical influence of site-specific habitat characteristics. We argue that local-scale management, which creates a unique “local habitat signature,” is a primary driver of community composition. We surveyed birds at 60 points across a diverse range of green spaces in a tropical metropolis, recording 148 species. Focusing on the 34 most frequent species, we used Redundancy Analysis (RDA) and variance partitioning to disentangle the effects of local, landscape, and spatial factors on bird communities. Our results showed that local-scale predictors consistently explained the largest proportion of unique variance for both taxonomic (9%) and functional (16%) compositions. The taxonomic analysis identified three ecological groups based on their habitat requirements: (1) Open-Area Specialists, (2) Arboreal Understory Specialists, and (3) Urban Tree-Dwellers and Generalists. Similarly, the functional analysis separated traits associated with forest interiors from those adapted to disturbed environments. The distribution of these groups was strongly tied to specific management practices, especially of soil cover, such as the presence of unmanaged tall grass or litter. Our findings demonstrate that urban biodiversity is mostly shaped by a mosaic of local habitat conditions. However, the surrounding landscape and the spatial arrangement of habitats also influenced community composition, underscoring the importance of a multi-scale approach to assess urban biodiversity composition for effective urban planning.

Range shifts along elevational gradients are a common response of species to changing climate, particularly in tropical regions where temperature decreases sharply with elevation. In this study, we investigate the current and future distribution of seven Geositta species (Furnariidae), which inhabit arid and semi-arid open habitats across different elevations in South America. Using ecological niche modeling, we assessed climatic suitability under two climate change scenarios: an optimistic scenario with reduced emissions and a pessimistic scenario with continued high emissions. Species distribution models were generated with the MAXENT algorithm, using 100 replicates per species. Future projections, based on two General Circulation Models (2061–2080), evaluated the influence of elevation on climatic niche availability. Our results indicate that six of the seven Geositta species will likely face significant habitat loss under all scenarios, with the pessimistic scenario causing the most severe reductions. Climatic suitability patterns differed between lowland and highland species, influenced by vegetational and elevational zonation of the Andean slopes. For highland species, suitable conditions were mostly restricted to higher elevations within their current ranges, reflecting the geographic constraints that limit their ability to shift upslope. These findings highlight the vulnerability of Geositta to climate change, stressing the urgency of conservation efforts. Protecting mid- to high-elevation habitats and transitional zones, while reducing anthropogenic pressures, will be key to safeguarding species with limited dispersal abilities. Although our models suggest most species are likely to retain substantial portions of their climatically suitable range, their future persistence may still depend on habitat availability, dispersal capacity, and other ecological constraints.