Multidimensional analyses of reptile assemblages: insights from phylogenetic, functional, and taxonomic diversity

Multidimensional biodiversity approaches provide a framework for understanding the ecological and evolutionary processes that shape communities through time and space. In this study, we assess the spatial variation in taxonomic, phylogenetic, and functional diversity of reptile assemblages along Chile's latitudinal gradient to gain insight into the primary assembly processes structuring these communities. We compiled data on distribution, phylogeny, and functional traits and estimated alpha diversity indices of taxonomic, phylogenetic, and functional dimensions. We then assessed the assembly process under the stress dominance hypothesis (SDH), using null models to test whether the observed phylogenetic and functional diversity deviated from random patterns, suggesting the influence of habitat filtering or interspecific competition. We also examined environmental influences on diversity metrics. Our results show that phylogenetic diversity is a poor proxy for functional diversity, highlighting the importance of multidimensional approaches to understanding the drivers of assemblage composition and structure. In support of the SDH, habitat filtering influenced reptile assemblages in arid and cold environments, whereas interspecific competition influenced the assemblages in milder environments, such as the Mediterranean region and Valdivian forests. Furthermore, the spatial mismatch between diversity metrics allowed us to explore how assemblage composition and structure are influenced by local environmental heterogeneity, biogeographic history, and adaptive radiations of squamate reptiles. Environmental variables, particularly temperature, primary productivity, and topographic complexity, emerged as strong predictors of reptile diversity. Our study highlights the importance of integrating species' evolutionary history and ecological traits with taxonomic richness to improve our understanding of community composition, ecosystem functioning, history, and resilience.