Phylogeographic structure and signals of selection provide insight into the range expansion of the Mexican Long-nosed Armadillo ( Dasypus mexicanus )

Abstract Many mammalian species have been experiencing widespread range expansions, accelerated by various environmental changes in the Anthropocene. These expansions serve as natural experiments, showcasing how organisms adapt and persist while navigating a mosaic of environmental conditions, and they also reveal the dynamic processes that drive species to push their boundaries and thrive in the face of new ecological challenges. The objective of this study was to explore genetic structure of the rapidly expanding Mexican Long-nosed Armadillo (Dasypus mexicanus) in the United States. We collected tissue samples and used the double-digest restriction-site associated DNA sequencing (ddRADseq) approach to generate 14,322 SNPs from 80 individuals, mapped to the Mexican Long-nosed Armadillo genome. We performed phylogeographic analyses and genomic scans for selection to describe genetic signals of the range expansion. We hypothesized that D. mexicanus—a highly mobile, generalist mammal with a broad colonization front would deviate from the typical genetic patterns expected in species undergoing a range expansion. Indeed, our findings revealed no geographic structure, high levels of admixture across United States, and high levels of heterozygosity. We detected numerous loci showing a signal of selection, indicating that the range expansion into colder climates may be facilitated by local adaptation. Our research enhances our understanding of the mechanisms underlying range expansion that are likely typical for medium-sized mammals, and evolutionary dynamics during colonization into new and heterogeneous environments.