Antitrendy mouse evolution

A paper in this week's Science by Hopi Hoekstra and colleagues (DOI link) ends with this provocative paragraph:

This work has specific implications for understanding the evolutionary mechanisms responsible for adaptive phenotypic change. First, the identification and functional characterization of a single amino acid mutation's effect on quantitative variation provides a convincing exception to a growing number of examples demonstrating that variation in morphology is governed by changes in gene regulatory regions (19, 20). Second, the observation that different combinations of alleles can produce similar pigmentation patterns suggests that distinct molecular mechanisms can underlie adaptive convergence even in similar selective environments (but see 21). Finally, Mc1r represents a large effect locus, containing a quantitative trait nucleotide (QTN) contributing to variation in fitness, consistent with the view that adaptation may often proceed by large steps (Hoekstra et al. 2006:104).

That certainly packs in a lot of contrarianism on the main recent strains of "how phenotypic evolution works" literature.

The study itself is about pigmentation in Florida beach mice, which are more lightly colored to blend in to dunes. They found that an amino acid change in Mc1r had a large effect on lighter pigmentation in Gulf Coast mice, and not Atlantic mice (hence the different mechanisms of adaptive convergence).

It is most interesting to see pushback against the "regulatory evolution" story that has been strongly emerging in the past several years.

References:

Hoekstra HE, Hirschmann RJ, Bundey RA, Insel PA, Crossland JP. 2006. A single amino acid mutation contributes to adaptive beach mouse color pattern. Science 313:101-104. DOI link