Modelling the dispersal of the two main hosts of the raccoon rabies variant in heterogeneous environments with landscape genetics

Predicting the geographic spread of wildlife epidemics requires knowledge about the movement patterns of disease hosts or vectors. The field of landscape genetics provides valuable approaches to study dispersal indirectly, which in turn may be used to understand patterns of disease spread. Here, we applied landscape genetic analyses and spatially explicit models to identify the potential path of raccoon rabies spread in a mesocarnivore community. We used relatedness estimates derived from microsatellite genotypes of raccoons and striped skunks to investigate their dispersal patterns in a heterogeneous landscape composed predominantly of agricultural, forested and residential areas. Samples were collected in an area covering 22 000 km2 in southern Québec, where the raccoon rabies variant (RRV) was first detected in 2006. Multiple regressions on distance matrices revealed that genetic distance among male raccoons was strictly a function of geographic distance, while dispersal in female raccoons was significantly reduced by the presence of agricultural fields. In skunks, our results suggested that dispersal is increased in edge habitats between fields and forest fragments in both males and females. Resistance modelling allowed us to identify likely dispersal corridors used by these two rabies hosts, which may prove especially helpful for surveillance and control (e.g. oral vaccination) activities.

预测野生动物流行病的地理传播范围，需要掌握疾病宿主或传播媒介的移动模式。景观遗传学（landscape genetics）领域为间接研究物种扩散行为提供了极具价值的方法，而这些方法反过来可用于解析疾病的传播规律。本研究将景观遗传学分析与空间显式模型（spatially explicit models）相结合，旨在识别中型食肉动物群落中浣熊狂犬病的潜在传播路径。我们基于浣熊与条纹臭鼬（striped skunks）的微卫星基因型（microsatellite genotypes）计算亲缘关系估计值，以探究在以农业、森林与居民区为主的异质景观中二者的扩散模式。研究样本采集自魁北克南部一片面积达22000平方千米的区域，该区域于2006年首次检测到浣熊狂犬病毒株（raccoon rabies variant, RRV）。距离矩阵多元回归分析结果显示，雄性浣熊的遗传距离仅随地理距离变化，而农业用地的存在显著抑制了雌性浣熊的扩散行为。对于条纹臭鼬，研究结果表明，农田与森林片段之间的边缘生境可同时促进雌雄个体的扩散。抗性建模（resistance modelling）帮助我们识别出这两种狂犬病宿主可能使用的扩散廊道，这些廊道将为相关监测与防控（如口服疫苗接种（oral vaccination））工作提供重要支撑。