KSEF RDE: Dispersal Congruency and Population Structure Within Imperiled Host-parasite Systems

Freshwater mussels are one of the most threatened groups of taxa worldwide. Kentucky is a global hotspot for mussel diversity, yet 20 of 104 native mussel species have been extirpated. Although the causes for freshwater mussel declines are numerous, the requirement of a fish host for larval development factors into declines of many mussel species and has direct implications for mussel conservation. First, host abundance can influence the abundance of a mussel species at a particular location, and this is expected to influence genetic diversity in populations. Second, dependence on a host for dispersal directly ties dispersal and gene flow of mussel species to that of its host, and the geographic, ecological, and environmental factors that influence gene flow among host populations are expected to influence gene flow among mussel populations. Thus, freshwater mussel conservation centers on understanding the following question: To what extent do host-parasite interactions affect gene flow and population structure among mussel populations? Here, we propose to study population structure and gene flow across the shared Kentucky distribution of the salamander mussel (Simpsonaias ambigua) and its host, the mudpuppy (Necturus maculosus). We will use a genomic approach to perform fine-scale estimates of demography and gene flow for both species at various spatial scales. Collectively, this will permit a dynamic assessment of how the host-parasite interaction, and extrinsic barriers, impact gene flow and genetic variation within and between populations of an imperiled mussel system. Overall, our results will not just aid in conservation of this specific system, but will act as a model for future mussel conservation research within Kentucky and beyond. In addition, this study will offer insight into basic processes of dispersal, gene flow, and co-evolutionary processes for two functionally linked organisms.