Data from: Prelude to a panzootic: gene flow and immunogenetic variation in northern little brown myotis vulnerable to bat white-nose syndrome

The fungus that causes bat white-nose syndrome (WNS) recently leaped from eastern North America to the Pacific Coast. The pathogen’s spread is associated with the genetic population structure of a host (Myotis lucifugus). To understand the fine-scale neutral and immunogenetic variation among northern populations of M. lucifugus, we sampled 1142 individuals across the species’ northern range. We used genotypes at 11 microsatellite loci to reveal the genetic structure of, and directional gene flow among, populations to predict the likely future spread of the pathogen in the northwest and to estimate effective population size (Ne). We also pyrosequenced the DRB1-like exon 2 of the class II major histocompatibility complex (MHC) in 160 individuals to explore immunogenetic selection by WNS. We identified three major neutral genetic clusters: Eastern, Montane Cordillera (and adjacent sampling areas), and Haida Gwaii, with admixture at intermediate areas and significant substructure west of the prairies. Estimates of Ne were unexpectedly low (289–16 000). Haida Gwaii may provide temporary refuge from WNS, but the western mountain ranges are not barriers to its dispersal in M. lucifugus and are unlikely to slow its spread. Our major histocompatibility complex (MHC) data suggest potential selection by WNS on the MHC, but gene duplication limited the immunogenetic analyses.

导致蝙蝠白鼻综合征（white-nose syndrome, WNS）的真菌最近从北美东部蔓延至太平洋沿岸。该病原体的传播与宿主小棕蝠（Myotis lucifugus）的遗传种群结构紧密相关。为解析小棕蝠北部种群间的精细中性遗传变异与免疫遗传变异，我们在该物种的北部分布范围内采集了1142个个体样本。我们利用11个微卫星位点（microsatellite loci）的基因型信息，解析了种群的遗传结构与种群间的定向基因流（directional gene flow），以此预测该病原体在西北地区未来的潜在传播路径，并估算有效种群大小（effective population size, Ne）。此外，我们对160个个体的II类主要组织相容性复合体（major histocompatibility complex, MHC）的DRB1样外显子2进行了焦磷酸测序，以探究蝙蝠白鼻综合征带来的免疫遗传选择压力。本研究鉴定出三个主要的中性遗传聚类群：东部聚类群、山地科迪勒拉（及邻近采样区域）聚类群以及海达瓜依（Haida Gwaii）聚类群，中间过渡区域存在遗传混杂，且草原以西区域存在显著的群体亚结构。有效种群大小的估算值异常偏低，区间为289~16000。海达瓜依或可成为蝙蝠白鼻综合征的临时避难所，但西部山地并未成为小棕蝠种群扩散的屏障，亦不太可能减缓该病原体的蔓延速度。本研究的主要组织相容性复合体（MHC）数据显示，蝙蝠白鼻综合征可能对MHC存在选择压力，但基因复制现象限制了免疫遗传相关分析的开展。