Natural populations of beach mice exhibit a characteristic color pattern, relative to their mainland conspecifics, driven by natural selection for crypsis. We identified a derived, charge-changing amino acid mutation in the melanocortin-1 receptor (Mc1r) in beach mice, which decreases receptor function. In genetic crosses, allelic variation at Mc1r explains 9.8% to 36.4% of the variation in seven pigmentation traits determining color pattern. The derived Mc1r allele is present in Florida's Gulf Coast beach mice but not in Atlantic coast mice with similar light coloration, suggesting that different molecular mechanisms are responsible for convergent phenotypic evolution. Here, we link a single mutation in the coding region of a pigmentation gene to adaptive quantitative variation in the wild.

We isolated and characterized 60 novel microsatellite markers from the closely related oldfield mouse (Peromyscus polionotus) and deer mouse (Peromyscus maniculatus) for studies of conservation, ecological, quantitative and population genetics. We assessed all 60 markers in a wild population of Peromyscus polionotus rhoadsi (N = 20) from central Florida and found an average of nine alleles per marker and an observed heterozygosity (HO) of 0.66 (range = 0.00–1.00). These polymorphic markers contribute to the growing number of genomic resources for Peromyscus, an emerging model system for ecological and evolutionary research.