Phylogenetic Conservatism and Ambient Temperature Shape Spatial Variation in Bat Occupancy and Species Richness Along a Subtropical Elevational Gradient.

Steep elevational gradients are natural laboratories for understanding species-environment relationships, as they provide high environmental heterogeneity over accessible distances. If species can colonize all available environments, their distributions become mainly a product of their niches, offering a unique opportunity to study these dynamics. Here, we capitalized on this ideal scenario to test whether ecological traits and evolutionary history interact with environmental variables to shape the occupancy of 27 bat species along a ~1300 m elevational gradient in subtropical Brazil. Using a multi-species modeling approach, we integrated data from mist-netting and acoustic recorders, environmental variables, ecological traits, and phylogeny to generate estimates that represent the entire bat assemblage. We found that most bat species in our study area are restricted to low elevations, with only two high-elevation specialists. Ecological traits typically associated with bat-environment relationships, such as body mass, trophic level, wing morphology, and roost type, were poor predictors of species' responses to environmental variables. However, species' occupancy varied with site temperature (and thus, elevation) in a phylogenetically conserved manner. Based on previous studies, we speculate that physiological traits conserved within certain clades, such as the ability to enter torpor, likely drive these patterns. Our study sheds light on the deterministic drivers of bat occupancy along a heterogeneous environmental gradient and suggests that bat elevational niches are phylogenetically conserved in subtropical Brazil.