Spatial and non-spatial patterns of genetic diversity in Neotropical bats

Macroecological studies that predict genetic diversity and its correlation with other biodiversity dimensions are essential to conservation in a rapidly changing environment. However, in bats (order Chiroptera), studies associating abiotic or ecological traits that could help to predict genetic diversity are scarce, even for singular species. In the Neotropics, the highest concentration of mammal and amphibian genetic diversity has been found in the Andes mountains and the Amazon Rainforest, yet it is an open question whether bat genetic diversity is also higher in these regions, or even if any abiotic factors are correlated with bat genetic diversity. Additionally, it is not known if any species-level ecological traits should be significantly correlated with species-level genetic diversity. To test the hypothesis that there is a correlation between bat species diversity and average genetic diversity, I calculated intraspecific genetic diversities from publicly available mtDNA datasets collected from bats, one of the most diverse groups of mammals in the Neotropics with economic and ecological importance. I divided the study into two classes of analyses: non-spatial and spatial. In my non-spatial analyses, I estimated nucleotide diversity per bat species or OTU, and compared it to 19 environmental factors, two vegetation indices, five ecological traits, and phylogenetic family membership. In the spatial analyses, I used the same bioclimatic environmental variables, vegetation indices, and one measure of species richness, and compared these measures to average intraspecific genetic diversity calculated from 66 geographically distributed grid cells. Using a map of bat occurrence data, I estimated the average nucleotide diversity across bat species from each 300 x 300 km grid cell that contained at least three sequences of the same OTU. Across the same grid cells, I also compared these abiotic variables with a proxy of phylogenetic diversity derived from the total average pairwise distances among locally sampled allele copies. In my non-spatial analyses, I found a significant correlation between nucleotide diversity and the family-level taxonomy, geographic range size, trophic guild membership, annual precipitation, and precipitation of the wettest month. The spatial analyses showed that the highest estimates of genetic diversity and phylogenetic diversity are found in the Mesoamerican forests and the Andes mountains and that there was a positive and significant correlation between bat species richness and average intraspecific nucleotide diversity per grid cell. Temperature variables were positively correlated with average nucleotide diversity, and phylogenetic diversity was positively correlated with precipitation variables and vegetation. The best model explained around 24% of the average nucleotide diversity (Adjusted R²= 0.240), 20% of the phylogenetic diversity (Adjusted R²= 0.202) across the Neotropical region. However, the available bat mitochondrial DNA mined from public databases highlights many largely unsampled areas in the Neotropical region, which may be creating error and bias in overall results of this study. This study highlights the many gaps in knowledge and the importance of filling them to have a better understanding of species history, as well as potential species responses to climate change in the Neotropics