Conserved but flexible: Genetic control of mimicry in Heliconius butterfly wing patterns

It is now well known that convergent morphology can evolve via repeated recruitment of the same regulatory genes in different lineages. We here contrast three butterfly species, all classic examples of Müllerian mimicry. We use a genetic linkage map to show that a locus, Yb, controlling the presence of a yellow band in geographic races of H. melpomene maps precisely to the same location as the locus Cr, which has very similar phenotypic effects in its co-mimic H. erato. Furthermore, the same genomic location acts as a ’supergene’ determining multiple, sympatric morphs in a third species, H. numata, a species with a very different phenotypic appearance, whose many forms mimic different unrelated ithomiine butterflies in the genus Melinaea. Hence, a single locus from the multilocus colour pattern architecture in H. melpomene and H. erato appears to have gained control of the entire wing-pattern variability in H. numata, presumably as a result of selection for mimetic ’supergene’ polymorphism without intermediates. Our results imply that a conserved, yet relatively unconstrained mechanism underlying pattern switching can affect mimicry in radically different ways. We also show that adaptive evolution, both convergent and diversifying, can occur by the repeated involvement of the same genomic regions. In: Meeting Abstracts: 7th International Workshop on the Molecular Biology and Genetics of the Lepidoptera, August 20–26, 2006, Orthodox Academy of Crete, Kolympari, Crete, Greece