PHYLOGENETIC DIVERSIFICATION WITHIN THE SOREX CINEREUS GROUP (SORICIDAE)

John R Demboski,Joseph A Cook

doi:10.1644/1545-1542(2003)084<0144:pdwtsc>2.0.co;2

Abstract

Phylogenetic relationships among 8 members of the Sorex cinereus group (S. camtschatica, S. cinereus, S. haydeni, S. jacksoni, S. portenkoi, S. preblei, S. pribilofensis, and S. ugyunak) and S. longirostris were estimated using DNA sequence data from 2 mitochondrial genes, cytochrome b (1,140 base pairs) and nicotinamide adenine dinucleotide dehydrogenase 4 (582 base pairs). S. hoyi, S. monticolus, S. palustris, S. tenellus, S. trowbridgii, and S. vagrans also were included in our analyses. Phylogenetic analyses of the combined data recovered 2 major clades within the species group: a northern clade that includes the Beringian species (S. camtschatica, S. jacksoni, S. portenkoi, S. pribilofensis, and S. ugyunak), S. haydeni, and S. preblei and a southern clade that includes S. cinereus and S. longirostris. Mitochondrial DNA clades generally corresponded to previously identified morphological groups with 2 exceptions: inclusion of S. longirostris with S. cinereus in the southern clade and inclusion of S. preblei within the northern clade. With the exception of the 5 Beringian species, taxa were readily differentiated with strong bootstrap support in our topologies. We also noted phylogenetic concordance with the general ecological affiliations of each species; the northern clade generally includes xeric-affiliated species, whereas the southern clade includes species with mesic habitat affinities.

Highlights

University of Alaska Museum and Biochemistry and Molecular Biology Program, University of Alaska Fairbanks, 907 Yukon Drive, Fairbanks, AK 99775-6960, USA Present address of JRD: Biological Sciences Department, California State Polytechnic University, Pomona, 3801 West Temple Avenue, Pomona, CA 91768-4032, USA Present address of JAC: Biological Sciences, Idaho State University, Pocatello, ID 83209-8007, USA
Expanding on previous hypotheses that stressed the importance of Pleistocene glaciations (Hoffmann and Peterson 1967), van Zyll de Jong (1982, 1991) speculated that major diversification within the group coincided with the last major glacial expansion (Wisconsinan) and continued into the Holocene. van Zyll de Jong (1991) hypothesized that the Beringian clade diversified in Beringia and suggested that S. haydeni represented a southward migrant from this refugium to the northern Great Plains
We examined 46 individuals (Appendix I) representing 8 species of the S. cinereus group recognized by van Zyll de Jong (1991)

Summary

Introduction

The Sorex cinereus group comprises 11 species of long-tailed shrews with members distributed across North America and into northeastern Asia (Hutterer 1993; Fig. 1) This group includes the only Palaearctic representatives of the subgenus Otisorex (S. camtschatica, S. leucogaster, and S. portenkoi), the most widespread species of Sorex in North America (S. cinereus), and several oceanic (e.g., S. jacksoni) or continental (e.g., S. lyelli) island forms (Hall 1981). Comprehensive evolutionary synthesis of the S. cinereus group was not available until the expansive morphological treatment of the group by van Zyll de Jong (1991) His cladistic examination of quantitative (13 cranial measurements) and qualitative (e.g., dental pigmentation and pelage coloration) characters revealed 2 major clades within the S. cinereus group: ‘‘Beringian’’ (S. camtschatica, S. jacksoni, S. haydeni, S. leucogaster, S. portenkoi, and S. pribilofensis) and ‘‘southern’’ (S. lyelli, S. milleri, S. preblei, and subspecies of S. cinereus). Expanding on previous hypotheses that stressed the importance of Pleistocene glaciations (Hoffmann and Peterson 1967), van Zyll de Jong (1982, 1991) speculated that major diversification within the group coincided with the last major glacial expansion (Wisconsinan) and continued into the Holocene. van Zyll de Jong (1991) hypothesized that the Beringian clade diversified in Beringia and suggested that S. haydeni represented a southward migrant from this refugium to the northern Great Plains

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