Vista Nortena: Tracking historical diversification and contemporary structure in high latitude mesocarnivores.

摘要

Contemporary high latitude diversity may be largely structured due to vicariant events during major glaciations and subsequent species radiations during the Pleistocene. Little is known about how diversity was produced at high latitudes, although recent studies suggest that these regions may have increased rates of both speciation and extinction because of large scale climatic changes. In this study, I focus on the high latitude islands of the North Pacific Coast and track the historical processes responsible for contemporary diversification of multiple species. I characterize the holarctic distribution for Mustela erminea in light of three previously described monophyletic clades. Using a suite of molecular markers, I provide evidence for a mid-Pleistocene divergence of the species into the three distinct clades currently found in North America. I also use a comparative approach based on studies in Europe to draw parallels between the hypothesized diversification events. Finally, I hypothesize the location of potential refugia from which each clade may have arisen.;I examine the historical biogeography of two forest-associated mammals, the Pacific marten (Martes caurina) and the pine marten ( Martes americana). Although they are sister species and have similar ecologies, these species represent independent evolutionary trajectories within the region. M. caurina is a relictual species of late-Pleistocene colonization, while M. americana is a recent colonizer into the region.;Using information gleaned from previous studies, I look closer at the effects of contemporary island life on the two species of marten. In particular, I define levels of endemicity found on islands in the North Pacific for M. caurina. I use genetic parameters to measure heterozygosity, effective population size, and estimates of gene flow to describe population connectivity and dispersal in light of historical information known for each population.;Finally, I explore the implications of my work for land use policies within these North Pacific Coast archipelagos. Understanding both historical and contemporary processes that drive diversification and subsequent species assemblages across regional landscapes is required for making effective conservation plans, management decisions, and predictive models of landscape connectivity to ensure the persistence of species in these vulnerable high latitude biomes.