Genetic and ecological processes promoting early diversification in the lowland Mesoamerican bat Sturnira parvidens (Chiroptera: Phyllostomidae)

Abstract

With 22 species, Sturnira is the most speciose genus of frugivorous Neotropical bats. Sturnira parvidens inhabits lowland tropical areas from Mexico to Central America. The elevation of this taxon to species level was recent, and discrepancies with respect to its geographic limits and phylogenetic position continue to exist. In order to identify genetic and ecological processes likely involved in the diversification and current distribution of S. parvidens, we evaluated relationships, researched phylogeographic and demographic history, and tested the divergence/conservatism of the climatic niche of this bat. We used data from mitochondrial loci (cytochrome b and the hypervariable D-loop region I) and the nuclear recombination activating gene 1, in 173 samples of S. parvidens and 77 samples of related species. We performed Bayesian analyses to infer phylogenetic relationships and analyzed phylogeographic structure, genetic diversity, divergence times and historical demography. Sturnira bakeri is the sister group of S. parvidens, and inhabits Western Ecuador. The two species diverged c. 1.84Ma, and their distributions are disjunct and separated by Sturnira luisi. Within S. parvidens there are two haplogroups with nearly allopatric distributions that are limited to the Sierra Madre del Sur, on the Mexican Pacific Slope. The divergence time between haplogroups was c. 0.423Ma and we detected signals of demographic expansion. We also analyzed 526 occurrence data of S. parvidens to test for changes in environmental niche of this species. We detected signals of divergence of climatic niche, mainly in temperature and seasonality variables. Likely, both genetic and ecological processes have shaped the evolutionary history of S. parvidens. Despite many climatic fluctuations during the Pleistocene, only the most intense oscillations had an impact on these bats. In addition, ecological differentiation prevents admixture of genetic lineages that are in contact and lack apparent geographical barriers at the southern Sierra Madre del Sur. We concluded that speciation in Sturnira was promoted by this taxon’s ability to colonize new geographical and environmental spaces and form genetically structured groups when populations become isolated.