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. Para examinar la estructura de comunidades es necesario analizar las múltiples dimensiones de biodiversidad con el fin de proveer un entendimiento más completo de los factores ecológicos e históricos involucrados en la formación y mantenimiento de las comunidades locales. Para cuantificar los patrones de relación evolutiva en 31 comunidades de murciélagos ricas en especies distribuidas a lo largo de México usamos 3 índices de diversidad filogenética: Índice de Faith, Distancia Promedio al Vecino Más Cercano y Distancia Promedio de Pares. A pesar que cada medida de diversidad filogenética fue afectada de manera diferente por el tamaño del grupo de especies regional, nuestros resultados indican que 17 comunidades se encuentran sub-dispersadas, 13 están dispersadas al azar y solo una se ha dispersado más de lo esperado. La precipitación y la longitud geográfica están correlacionadas con el Índice de Faith, la temperatura se encuentra correlacionada con la Distancia Promedio al Vecino Más Cercano y la temperatura interactuando con la latitud y longitud, están correlacionadas con la Distancia Promedio de Pares.