Variation, Adaptation and Developmental Constraints in the Mimetic Butterfly Papilio dardanus

Summary Wing patterns in mimetic butterflies can diversify rapidly to match a chemically defended model, and polymorphic species as the African Mocker Swallowtail, Papilio dardanus, even may mimic several different models. Evolutionary geneticists have ascribed the accurate control of complex differences in wing patterns to the action of ‘supergenes’, i.e. tightly linked multiple genes each specifying particular elements of the wing pattern. However, this concept appears less plausible in the light of modern developmental biology. Instead, we propose that Turing type mechanisms of morphogen gradients may account for a co-ordinate system that while largely buffered from variation, can be modified to produce new or alternate phenotypes by changing a small set of parameters during wing development. The sequential specification of cells in the developing wing allows for the repeated intervention of regulatory components to affect the phenotype, producing complex variation even if genetic differences are small.