The genetic value of volans: assessing phylogenetics and population genetics of southern flying squirrels (Glaucomys volans) across their range and at the Kansas range edge

Abstract

Southern flying squirrels (Glaucomys volans) are both charismatic and understudied. A species largely dependent on hardwood forest ecosystems for survival due to diet, locomotion, and nesting preferences, G. volans are widespread throughout the eastern United States. Given the strong associations of the species with forests, understanding the genetic health, history, and connectivity of regional populations can inform broader understandings of forest health, species conservation, and wildlife management priorities. Despite G. volans’ wide range, most previous genetic work has focused along the northern edge of the species range, and large gaps in scientific knowledge have persisted to present. Among other considerations, morphologic assessments suggest the presence of four G. volans subspecies within the U.S., but no range wide phylogenetic assessments have been done. Further, species populations at range edges often experience environmental conditions that alter population connectivity, natural selection, and ultimately survival. My research includes both a range wide assessment and a regional focus on the western range edge of G. volans. In Kansas, G. volans is listed as a species of conservation concern largely due to a lack of data and knowledge as opposed to known population decline or genetic attributes. My master’s thesis focuses on addressing two critical knowledge gaps: (1) range-wide phylogenetic history and diversity and (2) the evolutionary legacy of western range edge populations in Kansas to understand conservation needs. First, I analyzed mitochondrial DNA to understand the maternal history of G. volans and population diversity. I employed third generation Nanopore MinION sequencing to generate complete mitogenomes, allowing for results to provide greater insight and greater confidence than is possible with only a single gene region. Based on mitochondrial DNA, I observed fewer genetic lineages of G. volans across the range than has been suggested through morphometric-based sub-species designations. In addition, I found high regional differentiation, and extremely low levels of genetic diversity at the species’ western range edge. Evidence also supports anthropogenic influences on range-edge inter-population diversity. Second, I expanded the genetic assessment to include thousands of independent loci from across the nuclear genome to assess phylogenetic and population structure, meaningful evolutionary units, including adaptative and management units, and regional diversity and differentiation. This dataset supported greater regional population structure, range-edge genetic fitness concerns, and indicated increased range-wide gene flow that suggests potential for human movement of this species through the pet trade. Ultimately, my research shows that G. volans contains two intra-specific lineages consistent with regional differentiation with overall relatively high genomic diversity, although there remain regional concerns and conservation needs for populations along the western range edge, particularly in Kansas.