Peromyscus mice as a model for studying natural variation

Abstract

The deer mouse (genus Peromyscus) is the most abundant mammal in North America, and it occupies almost every type of terrestrial habitat. It is not surprising therefore that the natural history of Peromyscus is among the best studied of any small mammal. For decades, the deer mouse has contributed to our understanding of population genetics, disease ecology, longevity, endocrinology and behavior. Over a century's worth of detailed descriptive studies of Peromyscus in the wild, coupled with emerging genetic and genomic techniques, have now positioned these mice as model organisms for the study of natural variation and adaptation. Recent work, combining field observations and laboratory experiments, has lead to exciting advances in a number of fields-from evolution and genetics, to physiology and neurobiology.

Keywords: Peromyscus; adaptation; ecology; evolution; mouse; natural history; the natural history of model organisms.

Figure 1.. Simplified phylogeny depicting the relationships among muroid rodent model organisms.

Peromyscus belong to the Cricetidae family, which includes voles (Microtus), hamsters (Mesocricetus), and New World rats and mice. Old World rats and mice belong to the Muridae family, which include the familiar laboratory rat (Rattus norvegicus) and mouse (Mus musculus). Muridae and Cricetidae diverged roughly 25 million years ago. Schematic based on based on phylogeny data from Steppan et al. (2004). Image credit, Nicole Bedford and Hopi Hoekstra. DOI: http://dx.doi.org/10.7554/eLife.06813.002

Figure 2.. North American distributions of eight Peromyscus species currently maintained as outbred laboratory stocks (based on data from Hall, 1981).

Some ranges are narrow and others are extensive, with many overlapping to a large extent. Simplified tree indicating phylogenetic relationships among taxa is shown; branch lengths are arbitrary (based on data from Bradley et al., 2007). The most widespread and ecologically diverse group is also the best represented in the laboratory: six P. maniculatus subspecies are maintained in laboratories across the United States. Collecting localities of colony founders are indicated by numbered squares (see also Table 2). Image credit, Nicole Bedford and Hopi Hoekstra. DOI: http://dx.doi.org/10.7554/eLife.06813.003

Figure 3.. The ecology of Peromyscus varies considerably both within and among species.

(A) The forest-dwelling deer mouse, P. maniculatus nubiterrae, perches high on a tree branch in Southwestern Pennsylvania. (B) The beach mouse, P. polionotus phasma, takes shelter among the dune grasses on Florida's Atlantic coast. (C) Its mainland counterpart, the oldfield mouse, P. polionotus sumneri, is typically found in fallow fields and is sympatric with the cotton mouse, P. gossypinus (D), which occupies adjacent stands of long leaf pine. Image credits: A, Evan P Kingsley; B, JB Miller; C, D, Nicole Bedford. DOI: http://dx.doi.org/10.7554/eLife.06813.005

Figure 4.. Genetic crosses between the pale beach mouse P. polionotus leucocephalus (top row left) and the darker mainland mouse P. p. polionotus (top row right) result in first-generation F₁ hybrids, all with intermediate coloration (second row).

Intercrosses between F₁ hybrids produce a variable F₂ generation, showing a continuous distribution of pigmentation phenotypes ranging from light to dark (third and fourth rows; Steiner et al., 2007). This segregation pattern—initially described by Francis Sumner—is among the earliest empirical evidence that several discrete loci may collectively contribute to a quantitative trait (Dobzhansky, 1937; see also Box 1). Image credit, Nicole Bedford and Hopi Hoekstra. DOI: http://dx.doi.org/10.7554/eLife.06813.008