title: Refining mimicry: phenotypic variation tracks the local optimum.
abstract: Müllerian mimicry between chemically defended preys is a textbook example of natural selection favouring phenotypic convergence onto a shared warning signal. Studies of mimicry have concentrated on deciphering the ecological and genetic underpinnings of dramatic switches in mimicry association, producing a well-known mosaic distribution of mimicry patterns across geography. However, little is known about the accuracy of resemblance between natural comimics when the local phenotypic optimum varies. In this study, using analyses of wing shape, pattern and hue, we quantify multimodal phenotypic similarity between butterfly comimics sharing the so-called postman pattern in different localities with varying species composition. We show that subtle but consistent variation between populations of the localized species, Heliconius timareta thelxinoe, enhance resemblance to the abundant comimics which drive the mimicry in each locality. Those results suggest that rarer comimics track the changes in the phenotypic optimum caused by gradual changes in the composition of the mimicry community, providing insights into the process by which intraspecific diversity of mimetic pattern may arise. Furthermore, our results suggest a multimodal evolution of similarity, with coordinated convergence in different features of the phenotype such as wing outline, pattern and hue. Finally, multilocus genotyping allows estimating local hybridization rates between H. timareta and comimic H. melpomene in different populations, raising the hypothesis that mimicry refinement between closely related comimics may be enhanced by adaptive introgression at loci modifying the accuracy of resemblance.
authors.affiliation: Institut de Systématique Evolution et Biodiversité, UMR 7205 CNRS - MNHN - UPMC - EPHE, Muséum National d'Histoire Naturelle, 45 rue Buffon, 75005, Paris, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Mérot
authors.affiliation: Institut de Systématique Evolution et Biodiversité, UMR 7205 CNRS - MNHN - UPMC - EPHE, Muséum National d'Histoire Naturelle, 45 rue Buffon, 75005, Paris, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Poul
authors.affiliation: Mécanismes Adaptatifs et Evolution, UMR 7179 CNRS, Museum National d'Histoire Naturelle, 1 avenue du petit château, 91800, Brunoy, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Théry
authors.affiliation: Institut de Systématique Evolution et Biodiversité, UMR 7205 CNRS - MNHN - UPMC - EPHE, Muséum National d'Histoire Naturelle, 45 rue Buffon, 75005, Paris, France.|Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 route de Mende, 34293, Montpellier 5, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Joron
mesh_terms: D000818:Animals; D000067558:Biological Mimicry; D002080:Butterflies / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D006824:Hybridization, Genetic; D010568:Peru; D010641:Phenotype; D010858:Pigmentation; D012641:Selection, Genetic; D014921:Wings, Animal / Q000033:anatomy & histology / Q000502:physiology
keywords: Müllerian mimicry; adaptation; colour pattern; fitness peak; gene flow; geographic variation; hybridization; lepidoptera; morphometrics; perfect mimicry