%0 Journal Article
%T Historic hybridization and persistence of a novel mito-nuclear combination in red-backed voles (genus Myodes)
%A Amy M Runck
%A Marjorie D Matocq
%A Joseph A Cook
%J BMC Evolutionary Biology
%D 2009
%I BioMed Central
%R 10.1186/1471-2148-9-114
%X Identification of M. rutilus and M. gapperi based on the degree of closure of the post-palatal bridge was concordant with the distribution of diagnostic nuclear MYH6 alleles; however, an 80 km zone of introgressed populations was identified. The introgressant form is characterized by having mitochondrial haplotypes closely related to the northern M. rutilus on a nuclear background and morphological characteristics of southern M. gapperi.Introgression appears to have been historic as pure populations of M. rutilus are now isolated to the north from introgressants or pure M. gapperi by the LeConte Glacier. As we do not find pure M. rutilus or M. gapperi individuals throughout the distribution of the introgressant form, it appears that the introgressants are a self-sustaining entity not requiring continued hybridization between pure parental forms to generate this novel combination of characters.The evolutionary significance of hybridization has been widely recognized in some taxa such as plants, but our understanding of how this process contributes to animal diversity, especially in vertebrates is relatively limited [1-3]. Ecological and demographic settings known to contribute to hybridization between otherwise well-defined species include newly established contact (such that behavioral, pre-zygotic filters to breeding may not exist) and low density of one or both parental species such that conspecific mating opportunities are limited [4]. Such biogeographic and demographic conditions are known to characterize many areas of interspecific, post-glacial contact where the leading edges of the expanding ranges of post-glacial colonizers meet [5-8]. Such regions provide a unique opportunity to examine the origin and maintenance of hybrid forms within an increasingly well-understood biogeographic and temporal framework.Hybrid zones between species are thought to be maintained by two primary classes of models that predict 1) differential fitness between pure parental and hy
%U http://www.biomedcentral.com/1471-2148/9/114