Molecular basis and evolution of visual mare recognition in Heliconius butterflies

Heliconius butterflies are known to use wing colouration as a mating cue. H. heurippa is one of the best candidates for speciation by hybridisation in nature. Its red-yellow wing pattern as well as its attraction towards red and yellow colour is assumed to have arisen as a by-product of hybridisation between the red-coloured H. melpomene melpomene and the yellow-coloured H. timareta linaresi. For assortative mating to be maintained among hybrids, alleles determining wing colouration are expected to be in linkage disequilibrium (LD) with alleles causing attraction to the respective colour, in order to counteract the force of recombination. In this study we specifically test whether gene(s) underlying attraction to red colouration are physically linked to the allele(s) causing red wing colouration in H. heurippa, by scoring visual preference of hybrids between H. heurippa and one of the putative parental species, H. t. linaresi.

Heliconius butterflies are known to use wing colouration as a mating cue. H. heurippa is one of the best candidates for speciation by hybridisation in nature. Its red-yellow wing pattern as well as its attraction towards red and yellow colour is assumed to have arisen as a by-product of hybridisation between the red-coloured H. melpomene melpomene and the yellow-coloured H. timareta linaresi. For assortative mating to be maintained among hybrids, alleles determining wing colouration are expected to be in linkage disequilibrium (LD) with alleles causing attraction to the respective colour, in order to counteract the force of recombination. In this study we specifically test whether gene(s) underlying attraction to red colouration are physically linked to the allele(s) causing red wing colouration in H. heurippa, by scoring visual preference of hybrids between H. heurippa and one of the putative parental species, H. t. linaresi.

Despite small interspecific differences in attraction to red colour, we were able to find evidence for a gene causing attraction to red colour in H. heurippa being physically linked to the optix region, which is responsible for presence or absence of the red wing band. This condition may have facilitated the homoploid hybrid speciation of H. heurippa.