(A, Reprinted, with permission, from Barrett et al. (Right panel) Increased attack rates on noncryptic clay models relative to cryptic clay models on both light (beach) and dark (inland) soils demonstrate that visually hunting predators are an important selective agent targeting color variation within and between P. The selection coefficient is given for this SNP. One of the three single-nucleotide polymorphisms (SNPs) (40 kb), but not the others, varies clinally. Pie charts and mice are arranged N (top) to S (bottom) and light allele frequencies are indicated in white. (Middle panel) Allele frequencies at three polymorphic sites (stars) within the pigmentation gene Agouti (large boxes: coding exons small boxes: untranslated exons) sampled from eight populations along the same N-S transect. (Left panel) Representative mice and soil sampled from collection sites along a 150-km transect from northwestern Florida (beach) to southeastern Alabama (inland). (B) Selection on coat color in the oldfield mouse Peromyscus polionotus. (Right panel) Relative to the complete Eda allele (C), individuals carrying the low Eda allele (L) enjoy decreased predation by insects (left) and increased growth rates in fresh water (right). Selection coefficients are given for selection against the low allele from July to October (s L ) and from selection against the complete allele from October to July (s C ). (Middle panel) Changes in low Eda allele frequency within a single generation in four replicate ponds (colored lines).
(Left panel) Complete (top), partial (middle), and low (bottom) lateral plate morphs. (A) Selection on body armor in the threespine stickleback, Gasterosteus aculeatus. Two examples for which both the targets (phenotypic and genotypic) and agents of natural selection have been identified.
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