title: Evolution of dominance mechanisms at a butterfly mimicry supergene.
abstract: Genetic dominance in polymorphic loci may respond to selection; however, the evolution of dominance in complex traits remains a puzzle. We analyse dominance at a wing-patterning supergene controlling local mimicry polymorphism in the butterfly Heliconius numata. Supergene alleles are associated with chromosomal inversion polymorphism, defining ancestral versus derived alleles. Using controlled crosses and the new procedure, Colour Pattern Modelling, allowing whole-wing pattern comparisons, we estimate dominance coefficients between alleles. Here we show strict dominance in sympatry favouring mimicry and inconsistent dominance throughout the wing between alleles from distant populations. Furthermore, dominance among derived alleles is uncoordinated across wing-pattern elements, producing mosaic heterozygous patterns determined by a hierarchy in colour expression. By contrast, heterozygotes with an ancestral allele show complete, coordinated dominance of the derived allele, independently of colours. Therefore, distinct dominance mechanisms have evolved in association with supergene inversions, in response to strong selection on mimicry polymorphism.
authors.affiliation: CNRS UMR 7205, Muséum National d'Histoire Naturelle, CP50, 45 rue Buffon, Paris 75005, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Poul
authors.affiliation: CNRS UMR 7205, Muséum National d'Histoire Naturelle, CP50, 45 rue Buffon, Paris 75005, France.
authors.forename: Annabel
authors.initials: A
authors.lastname: Whibley
authors.affiliation: CNRS UMR 7205, Muséum National d'Histoire Naturelle, CP50, 45 rue Buffon, Paris 75005, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Chouteau
authors.affiliation: CNRS UMR 7205, Muséum National d'Histoire Naturelle, CP50, 45 rue Buffon, Paris 75005, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Prunier
authors.affiliation: CNRS UMR 7205, Muséum National d'Histoire Naturelle, CP50, 45 rue Buffon, Paris 75005, France.
authors.forename: Violaine
authors.initials: V
authors.lastname: Llaurens
authors.affiliation: CNRS UMR 7205, Muséum National d'Histoire Naturelle, CP50, 45 rue Buffon, Paris 75005, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Joron
mesh_terms: D000483:Alleles; D000818:Animals; D002080:Butterflies / Q000235:genetics*; D019143:Evolution, Molecular; D005799:Genes, Dominant / Q000235:genetics*; D017344:Genes, Insect; D010641:Phenotype; D010858:Pigmentation / Q000235:genetics*; D011110:Polymorphism, Genetic; D014921:Wings, Animal