Morphological variation and taxonomy of chromosomally differentiated Peromyscus from the Pacific Northwest

Abstract

Analysis of 28 morphological characters supports the existence of two karyotypically defined species of Peromyscus on Vancouver Island and islands in the Queen Charlotte Strait and the Strait of Georgia. Morphology of insular and mainland populations from Washington and British Columbia is congruent with karyotypic data indicating that only the smaller, low fundamental number deer mice should be retained with Peromyscus maniculatus, and that the larger, high fundamental number forms should be referred to Peromyscus areas. Accordingly, P. maniculatus ranges throughout Vancouver Island, is the only deer mouse inhabiting the islands of the Strait of Georgia, and occurs on some of the more northern small islands. Insular forms of P. areas occur on northern and western Vancouver Island and on the islands in the Queen Charlotte Strait. The existence of two species in this geographic area indicates the need for a revision of the subspecific taxonomy. From the patterns of morphological variation among the examined populations of karyotypically characterized individuals, we offer hypotheses that should be tested in the development of formal intraspecific taxonomic decisions.

Systematic and Taxonomic Implications of Karyotypic, Electrophoretic, and Mitochondrial-Dna Variation in Peromyscus from the Pacific Northwest

“…From morphometric analysis of chromosomally identified specimens, Allard and Greenbaum (1988) demonstrated that populations previously thought to represent P. sitkensis from islands off northern Vancouver Island (Thomas, 1973) are associated with P. oreas from mainland Washington and Vancouver Island. Chromosomal (Gunn, 1988) and morphometric comparisons of P. areas to specimens of P. sitkensis from BaranoffIsland supported the hypothesis that these forms are conspecific, but distinct from P. maniculatus.…”

Body-size trends inPeromyscus(Rodentia: Cricetidae) on Vancouver Island, Canada, with comments on relictual gigantism

“…Peromyscus keeni was initially characterized as a separate species from P. maniculatus based on the larger body size and shorter tail length of P. keeni (Sheppe 1961; McTaggart-Cowan and Guiguet 1965). The taxonomy and distribution of P. keeni were later refined by Hogan et al (1993), who considered morphological, karyological, and genetic information (Osgood 1909; Gunn and Greenbaum 1986; Allard et al 1987; Allard and Greenbaum 1988). More recently, genetic studies based on mitochondrial cytochrome- b in modern mice confirm the species designation (Zheng et al 2003; Lucid and Cook 2004).…”

Microevolution Rate, Pattern, Process

“…Because our interest is in contemporary microevolution, only cases where evolution occurred within the approximate life span of a human being were considered (Dobzhansky, 1941, p.12;. In many cases the time frame of evolution, while brief on evolutionary time scales (hundreds to thousands of years), was longer than our working definition (e.g., Berry, 1969;Berry & Rose, 1975;Aquadro & Kilpatrick, 1981;Allard & Greenbaum, 1988). The studies used in our meta-analysis were: (1) Berry (1964), a study of Mus musculus on the Welsh island of Skokholm; (2) Berry, Jakobsen and Peters (1978), a study of M. musculus on the Scottish Faroe Islands;…”

“…Examples include studies of Peromyscus (Gill, 1980;Aquadro & Kilpatrick, 1981;Melton, 1982;Ashley & Wills, 1987;Allard & Greenbaum, 1988;Calhoun & Greenbaum, 1991;, Clethrionomys (Corbet, 1964), Mus (Davis, 1983) & Rattus (Patton, Yang & Myers, 1975;Yom-Tov, Yom-Tov & Moller, 1999). Examples include studies of Peromyscus (Gill, 1980;Aquadro & Kilpatrick, 1981;Melton, 1982;Ashley & Wills, 1987;Allard & Greenbaum, 1988;Calhoun & Greenbaum, 1991;, Clethrionomys (Corbet, 1964), Mus (Davis, 1983) & Rattus (Patton, Yang & Myers, 1975;Yom-Tov, Yom-Tov & Moller, 1999).…”