Evidence for Fine-Scale Genetic Structuring of a Florida Mouse (Podomys floridanus) Population in a Heterogeneous Upland Landscape

Gopher Tortoise Council, 41st Annual Meeting, Talk, November 15, 2019

Abstract: The Florida mouse (*Podomysfloridanus*) is endemic to Florida’s xeric sandhill and scrub habitats. Due to the widespread loss of these habitats, Podomys is currently considered “Near Threatened” by the IUCN Red List and is part of the Florida Fish and Wildlife Conservation Commission’s imperiled species management plan. Future management efforts for the species requires an understanding how both natural and anthropogenic fragmentation of Podomys habitat shapes connectivity of populations. The Ordway-Swisher Biological Station (OSBS) is a 9500+ acre research facility located approximately 20 miles east of Gainesville in North Central Florida. It consists of 11 natural plant communities, including multiple large swathes of sandhill separated by areas of mesic and hydric habitat. Using 21 microsatellite markers, we assessed whether two spatially adjacent groups of *Podomys* (N₁=73 and N₂=141) at OSBS separated by a combination of non-xeric areas exhibited genetic structure reflecting isolation. Analyses consisted of multiple individual-based approaches, including Principal Components Analysis (PCA), Bayesian clustering using STRUCTURE, and MEMGENE, a tool capable of detecting weak genetic signals within populations. The first two components of the PCA accounts for 4.7% of the genetic variation and a bi-plot of these two components shows a slight but distinct differentiation of the two regions. Similarly, STRUCTURE results show differentiation between the two groups. Finally, the MEMGENE results show small (R²=0.013) but significant support for the presence of genetic structure. Unexpectedly, the first MEMGENE component variable accounting for 26.1% of this variation shows a different pattern of structure than predicted, while the second MEMGENE component variable (19.9% of variation) shows the expected pattern. Combined, these results show evidence of weak genetic structure driven by fine-scale habitat heterogeneity, but raises questions about other potential confounding factors that could be influencing genetic structure in this population of *Podomys*.