Department of Biology, Molecular Ecology and Evolution Lab,Lund University,Lund,Sweden.
Department of Ecology, Evolution and Environmental Biology,Columbia University,New York, NY 10027,USA.
Parasitology. 2019 Feb;146(2):213-219. doi: 10.1017/S0031182018001130. Epub 2018 Jul 16.
The biogeographic histories of parasites and pathogens are infrequently compared with those of free-living species, including their hosts. Documenting the frequency with which parasites and pathogens disperse across geographic regions contributes to understanding not only their evolution, but also the likelihood that they may become emerging infectious diseases. Haemosporidian parasites of birds (parasite genera Plasmodium, Haemoproteus and Leucocytozoon) are globally distributed, dipteran-vectored parasites. To date, over 2000 avian haemosporidian lineages have been designated by molecular barcoding methods. To achieve their current distributions, some lineages must have dispersed long distances, often over water. Here we quantify such events using the global avian haemosporidian database MalAvi and additional records primarily from the Americas. We scored lineages as belonging to one or more global biogeographic regions based on infection records. Most lineages were restricted to a single region but some were globally distributed. We also used part of the cytochrome b gene to create genus-level parasite phylogenies and scored well-supported nodes as having descendant lineages in regional sympatry or allopatry. Descendant sister lineages of Plasmodium, Haemoproteus and Leucocytozoon were distributed in allopatry in 11, 16 and 15% of investigated nodes, respectively. Although a small but significant fraction of the molecular variance in cytochrome b of all three genera could be explained by biogeographic region, global parasite dispersal likely contributed to the majority of the unexplained variance. Our results suggest that avian haemosporidian parasites have faced few geographic barriers to dispersal over their evolutionary history.
寄生虫和病原体的生物地理历史很少与自由生活物种（包括其宿主）的历史进行比较。记录寄生虫和病原体在地理区域内传播的频率不仅有助于了解它们的进化，还可以了解它们是否可能成为新出现的传染病。鸟类的血孢子虫寄生虫（寄生虫属包括疟原虫、血变原虫和白细胞原生动物）是全球性分布的双翅目传播寄生虫。迄今为止，已有超过 2000 种鸟类血孢子虫谱系通过分子条形码方法被指定。为了达到目前的分布范围，一些谱系必须进行长距离的扩散，通常是通过水域。在这里，我们使用全球鸟类血孢子虫数据库 MalAvi 以及主要来自美洲的其他记录来量化这些事件。我们根据感染记录将谱系划分为一个或多个全球生物地理区域。大多数谱系仅限于一个区域，但有些谱系是全球性分布的。我们还使用细胞色素 b 基因的一部分来创建属级寄生虫系统发育，并将支持良好的节点标记为在区域同域或异域中有后代谱系。疟原虫、血变原虫和白细胞原生动物的后代姐妹谱系分别在调查的 11%、16%和 15%的节点中呈异域分布。尽管所有三个属的细胞色素 b 的分子方差中有一小部分可以用生物地理区域来解释，但寄生虫的全球扩散很可能对大部分未解释的方差做出了贡献。我们的研究结果表明，在进化历史上，鸟类血孢子虫寄生虫在扩散方面很少面临地理障碍。
