Data from: Patterns of diversity and spatial variability of (beta)β-defensin innate immune genes in a declining wild population of tree swallows

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 six 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 six genes showed synonymous and non-synonymous 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 two 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 two 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.

评估野生物种免疫基因在异质环境下的遗传变异与分布格局，对于深化我们对病原体压力以及宿主潜在抗性或感染流行率作用的理解至关重要。近年来研究者已针对野生环境中的β-防御素基因（β-defensin）展开研究，因其具有较高变异性，提示其可能在宿主先天免疫防御中发挥关键作用。本研究针对加拿大魁北克南部一个处于衰退状态的双色树燕（Tachycineta bicolor）种群（样本量N=160），对β-防御素家族的6个先天免疫基因的变异情况进行了分析。研究发现，6个基因在编码成熟肽的外显子区域均存在同义与非同义单核苷酸多态性（single nucleotide polymorphisms, SNPs）。上述结果表明，双色树燕体内的该类基因具有丰富的遗传多样性。研究结果提示该类基因可能与波动的病原体多样性存在潜在互作，但未发现其受到正向或负向选择的迹象。本研究还评估了在农业集约化程度差异显著的两个区域中，研究种群内β-防御素基因的遗传多样性分布是否存在差异。成年个体对其繁殖地具有高度的恋巢性，且两个区域内个体的免疫应答存在显著差异。然而，本研究未发现足够证据表明，在上述异质环境条件下，遗传变异的水平与分布存在显著差异。未来研究应聚焦于评估野生种群中β-防御素基因的遗传多样性与适合度相关性状之间的关联。