Diversifying selection on MHC class I in the house sparrow (Passer domesticus) |
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Authors: | CLAIRE LOISEAU,MURIELLE RICHARD&dagger ,STÉ PHANE GARNIER&Dagger ,OLIVIER CHASTEL§ ,ROMAIN JULLIARD¶ ,RIMA ZOOROB, GABRIELE SORCI&Dagger |
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Affiliation: | Laboratoire Parasitologie Evolutive, CNRS UMR 7103,;Laboratoire Fonctionnement et Evolution des écosystèmes, CNRS UMR 7625, UniversitéPierre et Marie Curie, 7 quai St Bernard, Case 237, F-75252 Paris Cedex 05, France,;Laboratoire BioGéoSciences, CNRS UMR 5561, Universitéde Bourgogne, 6 Boulevard Gabriel, F-21000 Dijon, France,;Centre d'Etudes Biologique de Chizé, CNRS UPR 1934, F-79360 Beauvoir-sur-Niort, France,;Laboratoire Conservation des espèces, restauration et suivi des populations, CNRS UMR 5173, Muséum National d'Histoire Naturelle, 55 rue Buffon, F-75005 Paris, France,;Laboratoire Génétique moléculaire et intégration des fonctions cellulaires, CNRS FRE 2937, 7 rue Guy Mocquet, BP8, F-94801 Villejuif Cedex, France |
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Abstract: | Genes of the major histocompatibility complex (MHC) are the most polymorphic loci known in vertebrates. Two main hypotheses have been put forward to explain the maintenance of MHC diversity: pathogen-mediated selection and MHC-based mate choice. Host–parasite interactions can maintain MHC diversity via frequency-dependent selection, heterozygote advantage, and diversifying selection (spatially and/or temporally heterogeneous selection). In this study, we wished to investigate the nature of selection acting on the MHC class I across spatially structured populations of house sparrows ( Passer domesticus ) in France. To infer the nature of the selection, we compared patterns of population differentiation based on two types of molecular markers: MHC class I and microsatellites. This allowed us to test whether the observed differentiation at MHC genes merely reflects demographic and/or stochastic processes. At the global scale, diversifying selection seems to be the main factor maintaining MHC diversity in the house sparrow. We found that (i) overall population differentiation at MHC was stronger than for microsatellites, (ii) MHC marker showed significant isolation by distance. In addition, the slope of the regression of F ST on geographical distance was significantly steeper for MHC than for microsatellites due to a stronger pairwise differentiation between populations located at large geographical distances. These results are in agreement with the hypothesis that spatially heterogeneous selective pressures maintain different MHC alleles at local scales, possibly resulting in local adaptation. |
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Keywords: | balancing selection diversifying selection house sparrow MHC class I microsatellites Passer domesticus |
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