Odum School of Ecology, University of Georgia, 140 E. Green Street, Athens, GA 30602, USA
Center for the Ecology of Infectious Diseases, University of Georgia, Athens, USA.
Proc Biol Sci. 2018 Mar 14;285(1874). doi: 10.1098/rspb.2017.2613.
The distribution of parasites across mammalian hosts is complex and represents a differential ability or opportunity to infect different host species. Here, we take a macroecological approach to investigate factors influencing why some parasites show a tendency to infect species widely distributed in the host phylogeny (phylogenetic generalism) while others infect only closely related hosts. Using a database on over 1400 parasite species that have been documented to infect up to 69 terrestrial mammal host species, we characterize the phylogenetic generalism of parasites using standard effect sizes for three metrics: mean pairwise phylogenetic distance (PD), maximum PD and phylogenetic aggregation. We identify a trend towards phylogenetic specialism, though statistically host relatedness is most often equivalent to that expected from a random sample of host species. Bacteria and arthropod parasites are typically the most generalist, viruses and helminths exhibit intermediate generalism, and protozoa are on average the most specialist. While viruses and helminths have similar mean pairwise PD on average, the viruses exhibit higher variation as a group. Close-contact transmission is the transmission mode most associated with specialism. Most parasites exhibiting phylogenetic aggregation (associating with discrete groups of species dispersed across the host phylogeny) are helminths and viruses.
寄生虫在哺乳动物宿主中的分布是复杂的，这代表了它们感染不同宿主物种的不同能力或机会。在这里，我们采用宏观生态学的方法来研究影响寄生虫为何倾向于感染宿主进化枝中广泛分布的物种（进化枝广义性）而不是感染仅密切相关的宿主的因素。我们使用了一个数据库，其中包含了超过 1400 种寄生虫物种的记录，这些寄生虫已经感染了多达 69 种陆生哺乳动物宿主物种。我们使用三个度量标准的标准效应大小来描述寄生虫的进化枝广义性：平均成对进化枝距离（PD）、最大 PD 和进化枝聚集性。我们发现了一种向进化枝特化的趋势，尽管从统计学上讲，宿主亲缘关系通常与从宿主物种随机样本中预期的亲缘关系相当。细菌和节肢动物寄生虫通常是最广义的，病毒和寄生虫表现出中等程度的广义性，而原生动物平均是最特化的。虽然病毒和寄生虫的平均成对 PD 平均相似，但该组的变异程度更高。密切接触传播是与特化性最相关的传播模式。大多数表现出进化枝聚集性（与宿主进化枝中离散的物种群相关联）的寄生虫是蠕虫和病毒。
