title: Patterns of Diversity and Spatial Variability of β-Defensin Innate Immune Genes in a Declining Wild Population of Tree Swallows.
abstract: Assessing the genetic variation and distribution of immune genes across heterogeneous environmental conditions in wild species is essential to further our understanding of the role of pathogen pressure and potential resistance or prevalence in hosts. Researchers have recently investigated β-defensin genes in the wild, because their variability suggests that they may play an important role in innate host defense. This study investigated the variation occurring at 6 innate immune genes of the β-defensin family in a declining population of tree swallows (Tachycineta bicolor) in southern Québec, Canada (N = 160). We found that all 6 genes showed synonymous and nonsynonymous single nucleotide polymorphisms (SNPs) within the exon coding for the mature peptide. These results indicated that this group of genes was diverse in tree swallows. Our results suggested a potential interaction of this group of genes with fluctuating pathogen diversity, however, we found no sign of positive or negative selection. We assessed whether or not the distribution of genetic diversity of β-defensin genes in our study population differed between 2 regions that strongly differ in their level of agricultural intensification. Adults are highly philopatric to their breeding sites and their immunological responses differ between these 2 regions. However, we found little evidence that the level and distribution of genetic variability differed between these heterogeneous environmental conditions. Further studies should aim to assess the link between genetic diversity of β-defensin genes and fitness-related traits in wild populations.
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Clarence
authors.initials: C
authors.lastname: Schmitt
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Dany
authors.initials: D
authors.lastname: Garant
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Kathy
authors.initials: K
authors.lastname: Doyon
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bousquet
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Luc
authors.initials: L
authors.lastname: Gaudreau
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Marc
authors.initials: M
authors.lastname: Bélisle
authors.affiliation: From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
authors.forename: Fanie
authors.initials: F
authors.lastname: Pelletier
mesh_terms: D000818:Animals; D000835:Animals, Wild; D014644:Genetic Variation; D007113:Immunity, Innate; D046388:Swallows / Q000235:genetics / Q000276:immunology; D023083:beta-Defensins / Q000235:genetics
chemical_list: D023083:beta-Defensins
keywords: 
            Tachycineta bicolor
          ; agricultural intensification; beta(β)-defensin; selective pressure