File:Multigene Population Genetics and Microevolutionary Theory3 .12 book.png

English: Caption from the book: "A continuous phenotypic distribution produced by interactions between the genetic variation at a single locus with two alleles (A and a) with environmental variation. The locus is assumed to have an allele frequency of 0.5 and obeys Hardy–Weinberg, with the height of the histogram at the bottom of the figure indicating the genotype frequencies. The arrows coming from a genotype block in the histogram indicate that the same genotype can give rise to many phenotypes depending upon the environment. A thin solid line indicates the phenotypic distribution arising from the interaction of genotype AA with environmental variation, a thin small-dashed line the phenotypic distribution associated with Aa, and a thin large-dashed line with aa. The areas under these normal distributions are proportional to the genotype frequencies in the population. The thick solid line indicates the overall phenotypic distribution in the population that represents a mixture of the three genotypic specific distributions as weighted by the genotype frequencies." (Templeton)