adaptive variation in beach mice produced by two interacting pigmentation genes自适应变异在海滩老鼠由两个相互作用的色素基因.pdfVIP

PLoS BIOLOGY Adaptive Variation in Beach Mice Produced by Two Interacting Pigmentation Genes 1 2,3 2,3* Cynthia C. Steiner , Jesse N. Weber , Hopi E. Hoekstra 1 Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America, 2 Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America, 3 Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, United States of America Little is known about the genetic basis of ecologically important morphological variation such as the diverse color patterns of mammals. Here we identify genetic changes contributing to an adaptive difference in color pattern between two subspecies of oldfield mice (Peromyscus polionotus). One mainland subspecies has a cryptic dark brown dorsal coat, while a younger beach-dwelling subspecies has a lighter coat produced by natural selection for camouflage on pale coastal sand dunes. Using genome-wide linkage mapping, we identified three chromosomal regions (two of major and one of minor effect) associated with differences in pigmentation traits. Two candidate genes, the melanocortin-1 receptor (Mc1r) and its antagonist, the Agouti signaling protein (Agouti), map to independent regions that together are responsible for most of the difference in pigmentation between subspecies. A derived mutation in the coding region of Mc1r, rather than change in its expression level, contributes to light pigmentation. Conversely, beach mice have a derived increase in Agouti mRNA expression but no changes in protein sequence. These two genes also interact epistatically: the phenotypic