Conservation genomics of peripheral populations of the least shrew

Least shrews are broadly distributed across central and eastern North America, but are locally rare, and little is yet known about their evolutionary history. New populations occurring peripheral to the recognized distribution of C. parvus have been repeatedly discovered since the 1980s, progressively extending the known range of this species. It is hypothesized that populations in New Mexico represent two distinct taxa. With a reliance on declining mesic grassland habitats, least shrews are listed as threatened within New Mexico, but this listing requires additional genetic data to qualify existing relationships, including genetic diversity, connectivity, and taxonomic status. Northern lineages are hypothesized to be westward expansions thanks to increased irrigation drainage while southern populations are hypothesized to represent a relictual lineage of C. berlandieri, a species recognized to be distributed throughout southern Texas and Mexico. To test this, we performed a rangewide phylogeographic study using reduced representation genome sequencing to assess systematic relationships and investigate genetic diversity of NM populations compared with other clades.