Conservation genetics of the spotted bat: Insights from ancient, historical, and modern samples.

Spotted bats (Euderma maculatum) are cryptic (nocturnal, volant, and roost solitarily) and thus their biology remains largely undescribed. Only 35 specimens were known to science before the mid-1960s. Hence, they are ideal candidates for genetic studies to uncover population genetic diversity and structure, and thereby inform conservation. We analyzed nuclear microsatellite loci (N = 17) and mitochondrial control region sequences from 121 individuals spanning ancient (up to 2,100 years BP), historical (1904-1991), and contemporary (1994-2025) timeframes across the species' range in western North America, from Canada to Mexico. Ancient specimens shared haplotypes with modern individuals from the same locality, suggesting long-term population continuity. Microsatellite data revealed isolation-by-distance and a weak genetic cline from the genetically diverse U.S. Southwest core population into the less diverse northern range, consistent with male-biased dispersal and post-Pleistocene range expansion. Mitochondrial data showed stronger regional structure, with distinct haplogroups in the north, central, and southern populations. At a rare cave aggregation, analyses of fine‑scale relatedness identified father-son pairs and a male‑biased sex ratio, suggesting swarming behavior. Our integrative approach across temporal scales highlights the conservation importance of preserving genetically diverse core populations, vulnerable leading-edge populations, and isolated relict lineages.