Present address: Laboratoire d'Ecologie Animale et Entomologie, Institut de Zoologie, Université de Neuchâtel, CH-2007 Neuchâtel, Switzerland.
Mimicry: developmental genes that contribute to speciation
Article first published online: 28 APR 2003
2003 BLACKWELL PUBLISHING, INC.
Evolution & Development
Volume 5, Issue 3, pages 269–280, May 2003
How to Cite
Naisbit, R. E., Jiggins, C. D. and Mallet, J. (2003), Mimicry: developmental genes that contribute to speciation. Evolution & Development, 5: 269–280. doi: 10.1046/j.1525-142X.2003.03034.x
- Issue published online: 28 APR 2003
- Article first published online: 28 APR 2003
SUMMARY Despite renewed interest in the role of natural selection as a catalyst for the origin of species, the developmental and genetic basis of speciation remains poorly understood. Here we describe the genetics of Müllerian mimicry in Heliconius cydno and H. melpomene (Lepidoptera: Nymphalidae), sister species that recently diverged to mimic other Heliconius. This mimetic shift was a key step in their speciation, leading to pre- and postmating isolation. We identify 10 autosomal loci, half of which have major effects. At least eight appear to be homologous with genes known to control pattern differences within each species. Dominance has evolved under the influence of identifiable “modifier” loci rather than being a fixed characteristic of each locus. Epistasis is found at many levels: phenotypic interaction between specific pairs of genes, developmental canalization due to polygenic modifiers so that patterns are less sharply defined in hybrids, and overall fitness through ecological selection against nonmimetic hybrid genotypes. Most of the loci are clustered into two genomic regions or “supergenes,” suggesting color pattern evolution is constrained by preexisting linked elements that may have arisen via tandem duplication rather than having been assembled by natural selection. Linkage, modifiers, and epistasis affect the strength of mimicry as a barrier to gene flow between these naturally hybridizing species and may permit introgression in genomic regions unlinked to those under disruptive selection. Müllerian mimics in Heliconius use different genetic architectures to achieve the same mimetic patterns, implying few developmental constraints. Therefore, although developmental and genomic constraints undoubtedly influence the evolutionary process, their effects are probably not strong in comparison with natural selection.