Molecular Population Genetics of Coat-Color Variation in Pocket Mice

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9981810NachmanThe primary objective of the proposed research is to identifymutations responsible for naturally occurring coat-color variation inpopulations of light and dark rock pocket mice that live on light and darksubstrates. In particular, the proposed research will (1) documentvariation in coat color of mice and environmental heterogeneity in soilcolor for six paired localities in New Mexico and Arizona where each pairconsists of one light and one dark locality, (2) conduct a screen toidentify genes contributing to the observed phenotypic differences, (3)characterize mutant alleles at the loci implicated in phenotypicdifferences, and (4) characterize genetic variation at coat-color loci inpopulation samples from dark and light localities. Together, these studieswill (1) identify the number and relative effects of different genescontributing to coat color variation, (2) determine whether pigmentationdifferences are due primarily to structural changes, regulatory changes, orboth, (3) determine whether dark coat-color has evolved independently indifferent populations, and if it has, determine whether the same ordifferent mutations are involved, and (4) determine the extent to whichselection at one site in the genome has shaped patterns of geneticvariation at linked neutral sites. A central goal in biology is to explicitly connect genotype withphenotype for traits that are ecologically important. This has been anelusive goal because the genetic basis of most traits is not wellunderstood. Coat-color variation in rodents is a classic example ofphenotypic variation in response to local adaptation: in many species,dorsal pelage color closely matches the color of the soil on which theanimals live. A century of research on the genetics of coat color in housemice has produced a rich database of candidate genes and mutant effects.The combination of striking phenotypic variation in coat-color of pocketmice (Chaetodipus intermedius) and candidate pigmentation loci cloned inthe laboratory mouse presents an unparalleled opportunity to investigatethe genetic variation underlying a key morphological trait in nature.