From the Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, CanadaJ1K 2R1.
J Hered. 2017 Apr 1;108(3):262-269. doi: 10.1093/jhered/esx005.
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.
评估野生物种在异质环境条件下免疫基因的遗传变异和分布对于深入了解病原体压力和宿主潜在抗性或流行的作用至关重要。研究人员最近研究了野生 β-防御素基因，因为它们的变异性表明它们可能在先天宿主防御中发挥重要作用。本研究调查了加拿大魁北克南部（N = 160）数量下降的树燕（Tachycineta bicolor）中 β-防御素家族的 6 种固有免疫基因的变异情况。我们发现，所有 6 种基因在成熟肽编码的外显子中都显示出同义和非同义单核苷酸多态性（SNP）。这些结果表明，这群基因在树燕中是多样化的。我们的结果表明，这群基因可能与波动的病原体多样性相互作用，但我们没有发现正选择或负选择的迹象。我们评估了我们研究种群中 β-防御素基因遗传多样性的分布是否在 2 个在农业集约化程度上存在显著差异的区域之间存在差异。成年鸟对其繁殖地高度恋家，它们的免疫反应在这 2 个区域之间存在差异。然而，我们几乎没有证据表明遗传变异性的水平和分布在这些异质环境条件下存在差异。进一步的研究应该旨在评估 β-防御素基因的遗传多样性与野生种群中与适应性相关的特征之间的联系。
