title: Negative relationships between cellular immune response, Mhc class II heterozygosity and secondary sexual trait in the montane water vole.
abstract: Heterogeneities in immune responsiveness may affect key epidemiological parameters and the dynamics of pathogens. The roles of immunogenetics in these variations remain poorly explored. We analysed the influence of Major histocompatibility complex (Mhc) genes and epigamic traits on the response to phytohaemagglutinin in males from cyclic populations of the montane water vole (Arvicola scherman). Besides, we tested the relevance of lateral scent glands as honest signals of male quality. Our results did not corroborate neither the hypotheses of genome-wide heterozygosity-fitness correlation nor the Mhc heterozygote advantage. We found a negative relationship between Mhc hetetozygosity and response to phytohaemagglutinin, mediated by a specific Mhc homozygous genotype. Our results therefore support the hypothesis of the Arte-Dqa-05 homozygous genotype being a 'good' Mhc variant in terms of immunogenetic quality. The development of the scent glands seems to be an honest signal for mate choice as it is negatively correlated with helminth load. The 'good gene' hypothesis was not validated as Arte-Dqa-05 homozygous males did not exhibit larger glands. Besides, the negative relationship observed between the size of these glands and the response to phytohaemagglutinin, mainly for Mhc homozygotes, corroborates the immunocompetence handicap hypothesis. The Mhc variants associated with larger glands remain yet to be determined.
authors.affiliation: Centre de Biologie et Gestion des Populations UMR (INRA/IRD/Cirad/Montpellier SupAgro), INRA-EFPA Montferrier sur Lez Cedex, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Charbonnel
authors.affiliation: Centre de Biologie et Gestion des Populations UMR (INRA/IRD/Cirad/Montpellier SupAgro), INRA-EFPA Montferrier sur Lez Cedex, France ; Department of Population Biology, Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic Studenec, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Bryja
authors.affiliation: Centre de Biologie et Gestion des Populations UMR (INRA/IRD/Cirad/Montpellier SupAgro), INRA-EFPA Montferrier sur Lez Cedex, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Galan
authors.affiliation: IFREMER, Département Environnement, Microbiologie et Phycotoxines, Laboratoire de Microbiologie, ZI de la pointe du diable Plouzané, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Deter
authors.affiliation: Centre de Biologie et Gestion des Populations UMR (INRA/IRD/Cirad/Montpellier SupAgro), INRA-EFPA Montferrier sur Lez Cedex, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Tollenaere
authors.affiliation: Centre de Biologie et Gestion des Populations UMR (INRA/IRD/Cirad/Montpellier SupAgro), INRA-EFPA Montferrier sur Lez Cedex, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Chaval
authors.affiliation: Université Montpellier II, CNRS, Institut des Sciences de l'Evolution de Montpellier Montpellier Cedex, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Morand
authors.affiliation: Centre de Biologie et Gestion des Populations UMR (INRA/IRD/Cirad/Montpellier SupAgro), INRA-EFPA Montferrier sur Lez Cedex, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Cosson
keywords: Dqa and Drb; Mhc class II genes; abundance cycles; immunocompetence handicap; parasite-mediated balancing selection; sexual selection