Research Article

Linking a mutation to survival in wild mice

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Science  01 Feb 2019:
Vol. 363, Issue 6426, pp. 499-504
DOI: 10.1126/science.aav3824

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How natural selection affects mouse coat color

Evolution, at its core, involves changes in the frequency of alleles subject to natural selection. But identifying the target of selection can be difficult. Barrett et al. investigated how allele frequencies affecting pigmentation change over time (see the Perspective by Pelletier). Wild-caught mice (Peromyscus maniculatus) were exposed to avian predators against naturally occurring dark or light backgrounds. Natural selection yielded shifts in coloration owing to genetic variants in the mouse coat color Agouti gene.

Science, this issue p. 499; see also p. 452


Adaptive evolution in new or changing environments can be difficult to predict because the functional connections between genotype, phenotype, and fitness are complex. Here, we make these explicit connections by combining field and laboratory experiments in wild mice. We first directly estimate natural selection on pigmentation traits and an underlying pigment locus, Agouti, by using experimental enclosures of mice on different soil colors. Next, we show how a mutation in Agouti associated with survival causes lighter coat color through changes in its protein binding properties. Together, our findings demonstrate how a sequence variant alters phenotype and then reveal the ensuing ecological consequences that drive changes in population allele frequency, thereby illuminating the process of evolution by natural selection.

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