title: Investigating the role of the melanocortin-1 receptor gene in an extreme case of microgeographical variation in the pattern of melanin-based plumage pigmentation.
abstract: The Réunion grey white-eye (Zosterops borbonicus) is a single-island endemic passerine bird that exhibits striking geographically structured melanic polymorphism at a very small spatial scale. We investigated the genetic basis of this color polymorphism by testing whether the melanocortin-1 receptor (MC1R), a gene often involved in natural melanic polymorphism in birds, was associated with the observed plumage variation. Although we found three non-synonymous mutations, we detected no association between MC1R variants and color morphs, and the main amino-acid variant found in the Réunion grey white-eye was also present at high frequency in the Mauritius grey white-eye (Zosterops mauritianus), its sister species which shows no melanic polymorphism. In addition, neutrality tests and analysis of population structure did not reveal any obvious pattern of positive or balancing selection acting on MC1R. Altogether these results indicate that MC1R does not play a role in explaining the melanic variation observed in the Réunion grey white-eye. We propose that other genes such as POMC, Agouti or any other genes involved in pigment synthesis will need to be investigated in future studies if we are to understand how selection shapes complex patterns of melanin-based plumage pigmentation.
  
  
  BACKGROUND
  All sequences submitted to Genbank. Accession number: JX914505 to JX914564.
authors.affiliation: Laboratoire Évolution et Diversité Biologique, UMR5174 CNRS - Université Paul Sabatier - ENFA, Toulouse, France.
authors.forename: Yann X C
authors.initials: YX
authors.lastname: Bourgeois
authors.forename: Joris A M
authors.initials: JA
authors.lastname: Bertrand
authors.forename: Christophe
authors.initials: C
authors.lastname: Thébaud
authors.forename: Borja
authors.initials: B
authors.lastname: Milá
mesh_terms: D000596:Amino Acids / Q000235:genetics; D000818:Animals; D001717:Birds / Q000235:genetics*; D005241:Feathers / Q000378:metabolism*; D056426:Genetic Loci / Q000235:genetics; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes / Q000235:genetics; D008436:Mauritius; D008543:Melanins / Q000235:genetics*; D008969:Molecular Sequence Data; D010858:Pigmentation / Q000235:genetics*; D044102:Receptor, Melanocortin, Type 1 / Q000235:genetics*; D017508:Reunion; D012641:Selection, Genetic
chemical_list: D000596:Amino Acids; D008543:Melanins; D044102:Receptor, Melanocortin, Type 1