School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada.
Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Sainte-Hyacinthe, QC, Canada.
J Hered. 2020 Aug 12;111(4):371-378. doi: 10.1093/jhered/esaa017.
Blacklegged ticks (Ixodes scapularis) are considered to be the main vector of Lyme disease in eastern North America. They may parasitize a wide range of bird and mammal hosts. Northward dispersal of blacklegged ticks has been attributed largely to movement of hosts to areas outside of the current range of the tick, in conjunction with climate change. To better understand the drivers of range expansion in the blacklegged tick, we need investigations of the genetic connectivity and differentiation of tick populations at a fine spatial scale using appropriate markers. In this study, we investigated genetic connectivity and differentiation in blacklegged ticks, in an area of putatively recent advance in Ontario and Quebec, Canada, using microsatellite markers. Our findings suggest patchy differentiation of alleles, no spatial pattern of genetic structure, and genetic subdivision within sites, which are consistent with the very limited evidence available near the leading edge of range expansion of blacklegged ticks into Canada. These findings are consistent with the prevailing hypothesis, drawn from a variety of fields of study, suggesting that migratory birds from a variety of regions may be bringing hitchhiking ticks northward into Canada.
黑腿蜱（Ixodes scapularis）被认为是北美东部莱姆病的主要传播媒介。它们可能寄生在多种鸟类和哺乳动物宿主上。黑腿蜱的向北扩散主要归因于宿主向蜱当前分布范围以外的地区移动，同时伴随着气候变化。为了更好地了解黑腿蜱的扩展范围的驱动因素，我们需要使用适当的标记物在精细的空间尺度上调查蜱种群的遗传连通性和分化。在这项研究中，我们使用微卫星标记物调查了加拿大安大略省和魁北克省一个被认为是黑腿蜱近期扩张地区的蜱的遗传连通性和分化。我们的研究结果表明等位基因的分化不均匀，没有遗传结构的空间模式，以及站点内的遗传细分，这与黑腿蜱进入加拿大的扩展前沿附近非常有限的证据一致。这些发现与从各种研究领域得出的流行假设一致，即来自不同地区的候鸟可能会将搭便车的蜱向北带入加拿大。
