title: Ancient balancing selection at tan underlies female colour dimorphism in Drosophila erecta.
abstract: Dimorphic traits are ubiquitous in nature, but the evolutionary factors leading to dimorphism are largely unclear. We investigate a potential case of sexual mimicry in Drosophila erecta, in which females show contrasting resemblance to males. We map the genetic basis of this sex-limited colour dimorphism to a region containing the gene tan. We find a striking signal of ancient balancing selection at the 'male-specific enhancer' of tan, with exceptionally high sequence divergence between light and dark alleles, suggesting that this dimorphism has been adaptively maintained for millions of years. Using transgenic reporter assays, we confirm that these enhancer alleles encode expression differences that are predicted to generate this pigmentation dimorphism. These results are compatible with the theoretical prediction that divergent phenotypes maintained by selection can evolve simple genetic architectures.
authors.affiliation: Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Yassin
authors.affiliation: Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Héloïse
authors.initials: H
authors.lastname: Bastide
authors.affiliation: Howard Hughes Medical Institute and Laboratory of Molecular Biology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Henry
authors.identifier: http://orcid.org/0000-0001-5056-2755
authors.initials: H
authors.lastname: Chung
authors.affiliation: Institut Systématique Evolution Biodiversité ISYEB-UMR 7205-CNRS-MNHN-UPMC-EPHE, Ecole Pratique des Hautes Etudes, Paris-Sciences-Lettres, Paris 75005, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Veuille
authors.affiliation: Laboratoire Evolution, Génomes, Comportement, Ecologie (EGCE), CNRS, IRD, University of Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91198, France.
authors.forename: Jean R
authors.initials: JR
authors.lastname: David
authors.affiliation: Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: John E
authors.identifier: http://orcid.org/0000-0003-2968-9545
authors.initials: JE
authors.lastname: Pool
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004330:Drosophila / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005260:Female; D008297:Male; D010858:Pigmentation / Q000235:genetics / Q000502:physiology*; D012641:Selection, Genetic; D012727:Sex Characteristics