PARENT SESSION

Genetics/Evolution 1 -- Session Chair: Hopi Hoekstra-- University Center, Kate Buchanan Room

THE GENETIC BASIS OF COMPLEX COLOR ADAPTATION IN ISLAND POPULATIONS OF PEROMYSCUS. Hopi E. Hoekstra, Catherine Yamada and Rachel J. Hirschmann. Ecology, Behavior and Evolution Section, Division of Biological Sciences9500 Gilman Drive, University of California at San Diego, La Jolla, CA, United States.

ABSTRACT- Characterizing the genetic basis of adaptive change within and between taxa is a fundamental challenge in evolutionary biology. In particular, we would like to know how specific genes produce diversity, and how natural selection acts on this variation. To address these questions, we take advantage of a system in which the ecological context of phenotypic variation is well understood, and the genetic basis of the phenotype is tractable. Here, we explore the molecular basis of color adaptation in deer mice (genus Peromyscus). Peromyscus polionotus occur in the southeastern US and also occur on several barrier islands off the coast of Alabama and Florida. These island populations of mice have lighter pigmentation and a reduction in pigmented areas (relative to mainland mice) driven by natural selection for crypsis to the light-colored sandy dunes they inhabit. We examined the role of one candidate pigmentation gene, the melanocortin-1 receptor (Mc1r), in generating the adaptive light-colored phenotype of the Santa Rosa Island beach mouse (P. p. lecuocephalus). First, by comparing the complete nucleotide sequence of the Mc1r gene from the Santa Rosa Island beach mice (P. p. lecuocephalus) to mainland populations (P. p. subgriseus), we identified a single charge-changing amino acid polymorphism in a functionally important region of this receptor. Second, we genotyped 500 F2 offspring generated by a leucocephalus x subgriseus cross to identify a statistical association between this amino acid polymorphism and phenotypic variation. Finally, we explored patterns of nucleotide variation in Mc1r, with particular attention to this amino acid site, within and between island and mainland populations of Peromyscus polionotus. Together these results suggest that examining the genetic basis of complex color variation in Peromyscus polionotus can identify alleles on which selection acts, providing a model to study adaptive phenotypic evolution in natural populations.

KEY WORDS: adaptation, color, Peromyscus, island