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Phylogeography of the dusky shrew, Sorex monticolus (Insectivora, Soricidae): insight into deep and shallow history in northwestern North America
Author(s) -
Demboski John R.,
Cook Joseph A.
Publication year - 2001
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2001.01260.x
Subject(s) - biology , phylogeography , monophyly , sorex , clade , ecology , shrew , zoology , range (aeronautics) , molecular phylogenetics , phylogenetic tree , biochemistry , materials science , gene , composite material
Phylogenetic relationships among the dusky shrew ( Sorex monticolus ) and eight related species ( S . bairdi , S . bendirii , S . neomexicanus , S. ornatus , S . pacificus , S . palustris , S . sonomae and S. vagrans ) were assessed using sequences from the mitochondrial cytochrome b gene (801 bp). Analyses using parsimony and maximum likelihood revealed significant molecular variation not reflected in previous morphological studies of these species. Conversely, three morphologically defined species ( S. bairdi , S. neomexicanus and S. pacificus ) were poorly differentiated. Sorex ornatus and S. vagrans represented basal taxa for a more inclusive group that included: (i) a widespread Continental clade containing S. monticolus (Arizona to Alaska, including S . neomexicanus ); (ii) a Coastal clade containing S. monticolus (Oregon to south‐east Alaska, including S . bairdi and S . pacificus ); (iii) the semiaquatic species ( S. bendirii and S . palustris ); and (iv) S. sonomae . Additional subdivision was observed within the Continental clade corresponding to populations from the northern and southern Rocky Mountains. Average uncorrected sequence divergence between the Coastal and Continental clades was 5.3% (range 4.5–6.2%), which exceeds many interspecific comparisons within this species complex and within the genus Sorex . Lack of resolution of internal nodes within topologies suggests a deep history of rapid diversification within this group. Late Pleistocene/Holocene glacial perturbations are reflected in the shallow phylogeographic structure within these clades in western North America. Our results suggest also that S. monticolus is not monophyletic under current taxonomic nomenclature. This perspective on phylogeographic history was developed within a growing comparative framework for other organisms in western North America.