| Historical and contemporary factors interact over different spatial scales to determine the intraspecific genetic diversity of an organism. The objective of my dissertation was to gain understanding of the interaction between these factors by examining their effects on the genetic structure of mountain whitefish (Prosopium williamsoni).; I examined the distribution of genetic variation across the range of mountain whitefish to explore the effects of historical factors at a large geographic scale and I compared my results with other species to learn about the species-specificity of these effects. I found evidence for five major genetic groups of mountain whitefish, which potentially reflects geographic isolation that occurred in glacial refugium. In the species surveyed, I found several examples of concordant geographic patterns of genetic differentiation that reflect similar responses to landscape features, as well as non-concordant patterns of differentiation that reflect either species-specific responses to landscape features or differences in aspects of their ecology and life history. I also found that gene flow occurred over a larger geographic scale for mountain whitefish than for other native salmonids.; On a smaller geographic scale, I examined interactions between contemporary factors by comparing the genetic structure of mountain whitefish to that of bull trout (Salvelinus confluentus) in the Clark Fork River, Montana. Mountain whitefish had much less genetic differentiation among local populations than bull trout, which potentially reflects differences in the physical location of spawning sites, population size, and spawning behavior. I examined the effects of a putative snout-related trophic polymorphism on genetic subdivision to further explore the effects of contemporary factors within a single population. I examined phenotypic variation in snout morphology and tested for assortative mating for this trait in the Bitterroot River, Montana. I found continuous snout variation and subtle but consistent differences in diet associated with this morphology. I did not find evidence for assortative mating and thus found no effect of this trait on genetic subdivision.; I was supported by an NSF Ecologist, Educators and Schools fellowship for one year. Here I present a mark-recapture class investigation I created during this fellowship. |
