Population genetics and phylogeography of the Brazilian free-tailed bat (Tadarida brasiliensis) reveal extensive gene flow across southern South America (Chiroptera: Molossidae)

Abstract

Tadarida brasiliensis is a widespread species ranging from the United States to the southern tip of South America. Population genetics studies have been conducted mainly in the northern populations, with only a few samples from South America being included in previous studies. The study of T. brasiliensis populations is relevant due to their ecological importance as an insectivorous species that consumes agricultural pests and their role as a reservoir of diverse pathogens that may represent a potential risk to humans and other animals. Our objective was to analyze the population genetic structure of T. brasiliensis in Argentina in order to better understand the migration patterns of the species in the southern tip of its distribution, evaluate its genetic variation, and predict the impact on the spread of associated viruses, which has direct application to guide sanitary control strategies. We analyzed samples of 94 individuals from 14 provinces of Argentina and the Autonomous City of Buenos Aires using double digestion restriction site-associated DNA sequencing (ddRADseq) technology to obtain variable nuclear genomic markers (SNPs). The average statistics of 29,715 unlinked SNPs revealed high genetic diversity in the samples and an absence of population structure throughout Argentina, suggesting that the population of T. brasiliensis in Argentina behaves as a single panmictic unit. Demographic analyses indicate that the Argentine population underwent a significant growth, starting at approximately 0.27 million years ago and reaching an estimated current effective population size of 2.7 million. The results of complementary analyses using sequences of the mitochondrial gene cytochrome b are consistent with these conclusions and provide further evidence for a deep split between the populations of North America, South America, and the Caribbean. Our findings are congruent with those of previous studies focusing on North American populations, which also found evidence of population expansion and lack of genetic structure within regional populations.