If a group of genes is located next to one another on the chromosome then, in a short time scale, they act as a single gene during genetic processes. This is advantageous in cases when the relevant gene participates in the formation of traits that exist in two or more forms that are advantageous for their carrier, where other forms of the trait that could be formed by random combination of the alleles in the relevant loci would be disadvantageous for their carrier. The occurrence of genes in closely neighbouring loci is then denoted as a supergene.

The best known cases of supergenes were described in study of mimesis in butterflies. Sometimes, a certain type of butterfly imitates several various kinds of poisonous or bad-tasting butterflies. A number of genes affecting the individual traits of the pattern are required for the creation of the relevant pattern on its wings. These genes are located close to one another on the chromosome, so that the parent passes on the relevant combination of alleles to its progeny together. Thus, the progeny consist almost entirely of individuals that inherit the relevant supergene from the father (and imitate one bad-tasting species of butterfly) or who inherited this supergene from the mother (and imitate another species of bad-tasting of butterfly). Individuals that inherited the recombined genotype, whose phenotype would thus not be similar to either of the imitated species and whose mimetic defense against predators would thus be reduced, occur in the progeny of the particular species only rarely.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more