The contemporary geographic distribution and interrelation of populations result from landscape structure, habitat specificity, and historical climate fluctuations. We examined the impact of Pleistocene environmental history on mitochondrial genealogies of the water shrew (Sorex palustris) in montane systems of western North America to test hypotheses concerning historical recolonization. Our main focus lies on the regional scale of the Pacific Northwest and the extent to which disjunct populations are associated with discrete, isolated mountains. We analyzed 87 specimens from the entire western portion of the species range to assess broadscale genealogical relationships. We then examined 61 individuals selected from 21 specific high-elevation sites in the Pacific Northwest to test whether these populations are structured in accord with distinct montane regions. Across western North America in general the relationship among S. palustris lineages is unresolved, suggesting a recent and rapid radiation from a common ancestral population. In the Pacific Northwest we found evidence of clades that are uniquely associated with individually isolated montane regions, clades that are distributed across several montane regions, and distinct clades that co-occur within the same montane region. We conclude that populations of S. palustris in western North America are derived from a single, southern, late-Pleistocene refugium. We also suggest that lineages shifted geographically by following the most northerly postglacial expansion of the boreal forest system.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 91 • No. 4