Fredensborg B L
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
Integr Comp Biol. 2014 Jul;54(2):149-58. doi: 10.1093/icb/icu051. Epub 2014 May 24.
A trade-off between resource-specialization and the breadth of the ecological niche is one of the most fundamental biological characteristics. A true generalist (Jack-of-all-trades) displays a broad ecological niche with little resource specialization while the opposite is true for a resource-specialist that has a restricted ecological niche that it masters. Parasites that manipulate hosts' behavior are often thought to represent resource-specialists based on a few spectacular examples of manipulation of the host's behavior. However, the determinants of which, and how many, hosts a manipulating parasite can exploit (i.e., niche breadth) are basically unknown. Here, I present an analysis based on published records of the use of hosts by 67 species from 38 genera of helminths inducing parasite increased trophic transmission, a widespread strategy of parasites that has been reported from many taxa of parasites and hosts. Using individual and multivariate analyses, I examined the effect of the host's and parasite's taxonomy, location of the parasite in the host, type of behavioral change, and the effect of debilitation on host-specificity, measured as the mean taxonomic relatedness of hosts that a parasite can manipulate. Host-specificity varied substantially across taxa suggesting great variation in the level of resource-specialization among manipulating parasites. Location of the parasite, level of debilitation, and type of host were all significant predictors of host-specificity. More specifically, hosts' behavioral modification that involves interaction with the central nervous system presumably restricts parasites to more closely related hosts than does manipulation of the host's behavior via debilitation of the host's physiology. The results of the analysis suggest that phylogenetic relatedness of hosts is a useful measure of host-specificity in comparative studies of the complexity of interactions taking place between manipulating parasites and their hosts.
资源专业化与生态位宽度之间的权衡是最基本的生物学特征之一。真正的通才（万事通）具有广泛的生态位，资源专业化程度较低，而资源专家则相反，其生态位较窄且专精于此。基于一些操纵宿主行为的惊人例子，操纵宿主行为的寄生虫通常被认为是资源专家。然而，操纵性寄生虫能够利用哪些宿主以及能利用多少宿主（即生态位宽度）的决定因素基本上尚不清楚。在此，我基于已发表的记录进行了一项分析，这些记录涉及来自38个属的67种蠕虫对宿主的利用情况，这些蠕虫会诱导寄生虫增加营养传播，这是一种广泛存在的寄生虫策略，已在许多寄生虫和宿主类群中被报道。通过个体分析和多变量分析，我研究了宿主和寄生虫的分类学、寄生虫在宿主体内的位置、行为变化类型以及宿主衰弱对宿主特异性的影响，宿主特异性以寄生虫能够操纵的宿主的平均分类学相关性来衡量。宿主特异性在不同类群之间差异很大，这表明操纵性寄生虫之间的资源专业化水平存在很大差异。寄生虫的位置、衰弱程度和宿主类型都是宿主特异性的重要预测因素。更具体地说，与中枢神经系统相互作用的宿主行为改变可能会使寄生虫局限于关系更密切的宿主，而通过宿主生理衰弱来操纵宿主行为则不然。分析结果表明，在比较研究操纵性寄生虫与其宿主之间发生的相互作用的复杂性时，宿主的系统发育相关性是衡量宿主特异性的一个有用指标。
