title: Molecular mechanisms of dominance evolution in Müllerian mimicry.
abstract: Natural selection acting on dominance between adaptive alleles at polymorphic loci can be sufficiently strong for dominance to evolve. However, the molecular mechanisms underlying such evolution are generally unknown. Here, using Müllerian mimicry as a case-study for adaptive morphological variation, we present a theoretical analysis of the invasion of dominance modifiers altering gene expression through different molecular mechanisms. Toxic species involved in Müllerian mimicry exhibit warning coloration, and converge morphologically with other toxic species of the local community, due to positive frequency-dependent selection acting on these colorations. Polymorphism in warning coloration may be maintained by migration-selection balance with fine scale spatial heterogeneity. We modeled a dominance modifier locus altering the expression of the warning coloration locus, targeting one or several alleles, acting in cis or trans, and either enhancing or repressing expression. We confirmed that dominance could evolve when balanced polymorphism was maintained at the color locus. Dominance evolution could result from modifiers enhancing one allele specifically, irrespective of their linkage with the targeted locus. Nonspecific enhancers could also persist in populations, at frequencies tightly depending on their linkage with the targeted locus. Altogether, our results identify which mechanisms of expression alteration could lead to dominance evolution in polymorphic mimicry.
authors.affiliation: Institut de Systématique Evolution et Biodiversité, UMR7205, CNRS, EPHE, UPMC, Museum National d'Histoire Naturelle, Bâtiment d'entomologie, CP50, 45 rue Buffon, 75005, Paris, France. llaurens@mnhn.fr.
authors.forename: V
authors.initials: V
authors.lastname: Llaurens
authors.affiliation: Institut de Systématique Evolution et Biodiversité, UMR7205, CNRS, EPHE, UPMC, Museum National d'Histoire Naturelle, Bâtiment d'entomologie, CP50, 45 rue Buffon, 75005, Paris, France.|Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS-Universite de Montpellier-Universite Paul Valery Montpellier - EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 05, France.
authors.forename: M
authors.initials: M
authors.lastname: Joron
authors.affiliation: Unité Evo-Eco-Paléo, UMR CNRS 8198, Université des Sciences et Technologies de Lille 1, Bâtiment SN2, 59655, Villeneuve d'Ascq Cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Billiard
mesh_terms: D000818:Animals; D000067558:Biological Mimicry; D001717:Birds / Q000502:physiology; D002080:Butterflies / Q000235:genetics / Q000502:physiology*; D019143:Evolution, Molecular; D020387:Food Chain; D008957:Models, Genetic; D010858:Pigmentation; D011110:Polymorphism, Genetic; D011235:Predatory Behavior; D012641:Selection, Genetic
keywords: Balancing selection; enhancers; gene expression; modifier; polymorphism; spatial heterogeneity