BETA DIVERSITY PATTERNS OF ANURANS METACOMMUNITIES ALONG DIFFERENT VEGETATION TYPES IN ATLANTIC FOREST OF SOUTHERSTERN BRAZIL

Abstract

Beta diversity describes the variation in species composition among different locations and is composed of two components: species turnover and selective gains or losses (nestedness), which contribute to community assembly through processes such as niche filtering and selective colonization/extinction. Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD) can be used to identify key locations and species for conservation. Amphibians in the Atlantic Forest are particularly susceptible to environmental and spatial factors due to their limited dispersal capacity and dependence on different habitats throughout their life cycle. Previous studies have examined the role of historical climate change and geomorphological factors in explaining the phylogenetic beta diversity of amphibians in the Atlantic Forest, but more recent research has focused on the influence of functional traits on their distribution patterns. This study aims to investigate the patterns driving beta diversity of anuran metacommunities in five different vegetation types in the northern region of Rio de Janeiro state. We conducted field surveys of amphibian communities in 16 areas encompassing different vegetation types within the Atlantic Forest domain: Montane Rainforest (FOM), Submontane Rainforest (FOS), Restinga (RES), Tabuleiro (TAB), and Lowland (BAI). For each sampling area, we extracted 19 climatic variables from the BioClim dataset, and for each encountered species, functional traits were characterized based on literature records and previously collected specimens. A total of 1087 individuals representing 62 anuran species were recorded across the 16 areas. We found that different vegetation types contribute differently to LCBD at different scales. Different species also influenced different partitions of SCBD. Overall, variation in anuran species composition across the northern region of Rio de Janeiro can be predominantly explained by species turnover. RES exhibited the highest amphibian species richness but was not the most important vegetation type for LCBD, as it shared several species with other areas. In this case, both taxonomic and functional partitions of LCBD were more influenced by FOM and FOS due to the presence of unique species with distinctive functional traits. SCBD partitions were influenced by different species. While taxonomic SCBD was influenced by relatively common species found in at least half of the sampled areas, functional SCBD was influenced by rare species found only in one location and vegetation type. Additionally, taxonomic LCBD and functional LCBD were positively correlated with climatic variables, as areas with similar climatic characteristics exhibited similar diversity values. The results suggest that preserving different vegetation types is crucial for maintaining amphibian diversity, as different vegetation types contribute in different ways to local and functional beta diversity. Furthermore, our study highlights the importance of considering both taxonomic and functional diversity to understand amphibian distribution in the northern region of Rio de Janeiro state.