PDF(Pubmed)
Abstract：
Determining patterns of host use, and the frequency at which these patterns change, are of key importance if we are to understand tick population dynamics, the evolution of tick biodiversity, and the circulation and evolution of associated pathogens. The question of whether ticks are typically host specialists or host generalists has been subject to much debate over the last half-century. Indeed, early research proposed that morphological diversity in ticks was linked to host specific adaptations and that most ticks were specialists. Later work disputed this idea and suggested that ticks are largely limited by biogeographic conditions and tend to use all locally available host species. The work presented in this review suggests that the actual answer likely lies somewhere between these two extremes. Although recent observational studies support the view that phylogenetically diverse host species share ticks when found on similar ecological ranges, theory on host range evolution predicts that host specialization should evolve in ticks given their life history characteristics. Contemporary work employing population genetic tools to examine host-associated population structure in several tick systems support this prediction and show that simple species records are not enough to determine whether a parasite is a true host generalist; host specialization does evolve in ticks at local scales, but may not always lead to speciation. Ticks therefore seem to follow a pattern of being global generalists, local specialists. Given this, the notion of host range needs to be modified from an evolutionary perspective, where one simply counts the number of hosts used across the geographic distribution, to a more ecological view, where one considers host use at a local scale, if we are to better understand the circulation of tick-borne pathogens and exposure risks for humans and livestock.
摘要：
确定主机使用的模式，以及这些模式变化的频率，如果我们要了解蜱种群动态，蜱生物多样性的演变，以及相关病原体的循环和进化。在过去的半个世纪中，蜱虫通常是主持人专家还是主持人通才的问题一直受到很多争论。的确,早期的研究表明，壁虱的形态多样性与宿主特异性适应有关，而且大多数壁虱都是专家。后来的工作对这一想法提出了异议，并建议蜱虫在很大程度上受生物地理条件的限制，并倾向于使用所有本地可用的宿主物种。这篇评论中提出的工作表明，实际答案可能介于这两个极端之间。尽管最近的观察研究支持这样的观点，即在相似的生态范围内发现系统发育上不同的寄主物种共享蜱，关于寄主范围进化的理论预测，鉴于寄主的生活史特征，寄主的专业化应该在壁虱中进化。采用种群遗传工具来检查几种tick虫系统中与宿主相关的种群结构的当代工作支持了这一预测，并表明简单的物种记录不足以确定寄生虫是否是真正的宿主通才；宿主专业化确实在局部尺度上在蜱虫中进化，但可能并不总是导致物种形成。因此，壁虱似乎遵循了全球通才的模式，当地专家。鉴于此,宿主范围的概念需要从进化的角度进行修改，其中一个简单地计算整个地理分布中使用的主机数量，更生态的观点，在本地范围内考虑主机使用的情况下，如果我们要更好地了解蜱传病原体的循环以及人类和牲畜的暴露风险。
