Phylogeography of a Holarctic rodent (Myodes rutilus): testing high‐latitude biogeographical hypotheses and the dynamics of range shifts. (27th November 2014) - Kohli, Brooks A.
Abstract Aim We used the Holarctic northern red‐backed vole (Myodes rutilus) as a model organism to improve our understanding of how dynamic, northern high‐latitude environments have affected the genetic diversity, demography and distribution of boreal organisms. We tested spatial and temporal hypotheses derived from previous mitochondrial studies, comparative phylogeography, palaeoecology and the fossil record regarding diversification of M. rutilus in the Palaearctic and Beringia. Location High‐latitude biomes across the Holarctic. Methods We used a multilocus phylogeographical approach combined with species distribution models to characterize the biogeographical and demographic history of M. rutilus. Our molecular assessment included widespread sampling (more than 100 localities), species tree reconstruction and population genetic analyses. Results Three well‐differentiated mitochondrial lineages correspond to geographical regions, but nuclear genes were less structured. Multilocus divergence estimates indicated that diversification of M. rutilus was driven by events occurring before c. 100 ka. Population expansion in all three clades occurred prior to the Last Glacial Maximum (LGM) and presumably led to secondary contact. Species distribution modelling predicted a broad LGM distribution consistent with population and range expansion during this period. Main conclusions The biogeographical history of M. rutilus differs from other boreal forest‐associated species. Well‐differentiated clades and the existence of secondary contact zones indicate prolonged isolation and persistence in Eurasian and Beringian refugia. Dynamic demographic and distributional changes emphasize the impact of pre‐LGM glacial–interglacial cycles on contemporary geographical structure. The Bering Strait was not a significant factor in the diversification of northern red‐backed voles.