Dispersal, disturbance, and distance: the connection between ecological processes and spatial genetic patterns in the Pacific jumping mouse (Zapus trinotatus)

Thesis (Ph. D.)--University of Washington, 2005.Ecological mechanisms, such as dispersal, mating system, disturbance, and habitat affiliation can have profound impacts on genetic structure within a population, and on gene flow between populations. In this study, I isolated eight microsatellite loci from the Pacific jumping mouse (Zapus trinotatus ) and used these to explore three components of the relationship between ecological processes and genetic structure. First, the genetic data were combined with field collected data on animal activity to reveal patterns of natal dispersal, mate choice, and reproductive success, and to infer the impacts of these on genetic structure in a small, semi-isolated population of Pacific jumping mice on the Dosewallips River in Washington State. I found a direct connection between patterns of dispersal and mating system, and the standing spatial genetic structure present in the population. Females were philopatric and mated with multiple neighboring males. Dispersal was male biased, but interestingly was motivated by paternal avoidance. Consistent with these patterns, females were related and spatially structured, with proximal females more closely related than distant females, whereas these patterns were not present in males. The occurrence of a 25-year flood between the second and third year of this study allowed for the description of the impacts of the resulting bottleneck on this population. The spatial structuring found in the first component of the study in combination with the spatially explicit nature of the flood lead to spatially oriented survival and strong founder effects in the post-flood population; a rapid increase in relatedness, reduction in heterozygosity, and population divergence within a single generation. Finally, a GIS-based landscape genetics approach was used, in combination with fine scale spatial autocorrelation analysis and the estimation of recent intersubpopulation migration rates, to infer patterns of dispersal and migration among nine populations across the larger three river system that includes the Dosewallips, Duckabush, and Hamma Hamma rivers. Dispersal was found to be limited in distance and movement of Pacific jumping mice across the landscape was directed along riparian pathways. These results indicate that patterns of dispersal and migration in Pacific jumping mice are largely determined by riparian habitat connectivity