Environmental correlates of phylogenetic structure in Mexican bat communities.

Contemporary examination of community structure requires analyzing multiple dimensions of biodiversity to provide a more holistic understanding of the ecological and historical factors involved in the formation and maintenance of local communities. We used empirical data on bat communities across Mexico to investigate patterns of taxonomic and phylogenetic diversities. More specifically, we 1) characterized phylogenetic structure using multiple measures of diversity and identified environmental factors that serve as potential drivers of the underlying structure, 2) determined whether any bat community showed evidence of phylogenetic overdispersion or underdispersion and characterized how taxonomic structure differed among overdispersed, randomly dispersed, and underdispersed sites, and 3) examined the relationship between phylogenetic diversity and size of the regional species pool. We used 3 indices of phylogenetic diversity (Faith's index [FI], mean nearest neighbor distance [MNND], and mean pairwise distance [MPD]) to quantify patterns of evolutionary relatedness in bat communities across Mexico. To determine whether a particular community was overdispersed, randomly dispersed, or underdispersed, we used randomization procedures with latitudinal and longitudinal constraints to define the regional species pool for each bat community. We used regression trees to investigate which climatic factors explained variation for each measure of phylogenetic diversity. Precipitation and longitude were correlated with FI, temperature was correlated with MNND, and temperature along with latitude and longitude were correlated with MPD. We found that just over one-half of the communities were underdispersed, just under one-half were randomly dispersed, and only 1 was overdispersed. Each measure of phylogenetic diversity was differently affected by the size of the regional species pool. [ABSTRACT FROM AUTHOR]