Known to scientists as Peromyscus polionotus, mice living on the mainland have dark coats, which help them blend in with the vegetation and avoid their main predators--owls, hawks and herons--that hunt prey by sight. But on five barrier islands off the Florida Gulf coast and three off Northern Florida's Atlantic coast, geographic isolation of the populations has resulted in eight distinct subspecies of beach mice, each with distinctive coat patterns that are lighter in color than their mainland counterpart.
"We know from geological evidence that the barrier islands are very recent, less than 6,000 years old," says Hoekstra. "So these color mutations may have evolved rapidly."
While scientists have been studying the genetics of complex coat patterns of these mice for nearly a century, few suspected that the simple mutation of a single nucleotide could have such a major impact on their coloration.
"We were surprised that this one gene could explain up to 36 percent of the variation we see in the mice," she says. "It's a large effect mutation. And what it says is that adaptation does not always occur gradually, but may happen in these relatively large jumps."
Hoekstra and her colleagues--Rachel Hirschmann of UCSD's Division of Biological Sciences and Richard Bundey and Paul Insel of UCSD's Department of Pharmacology--discovered the single nucleotide mutation in the melanocortin-1 receptor, a gene which regulates the pigmentation of hair color.
In laboratory mating of the different subspecies to produce genetic crosses, the UCSD scientists report in their paper that the v
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Contact: Kim McDonald
kmcdonald@ucsd.edu
858-534-7572
University of California - San Diego
6-Jul-2006