Center for Conservation and Evolutionary Genetics, National Zoological Park, Smithsonian Institution, 3001 Connecticut Avenue, Washington, DC 20008, USA.
Int J Parasitol. 2009 Jan;39(2):257-66. doi: 10.1016/j.ijpara.2008.06.005. Epub 2008 Jul 26.
The host specificity of blood parasites recovered from a survey of 527 birds in Cameroon and Gabon was examined at several levels within an evolutionary framework. Unique mitochondrial lineages of Haemoproteus were recovered from an average of 1.3 host species (maximum=3) and 1.2 host families (maximum=3) while lineages of Plasmodium were recovered from an average of 2.5 species (maximum=27) and 1.6 families (maximum=9). Averaged within genera, lineages of both Plasmodium and Haemoproteus were constrained in their host distribution relative to random expectations. However, while several individual lineages within both genera exhibited significant host constraint, host breadth varied widely among related lineages, particularly within the genus Plasmodium. Several lineages of Plasmodium exhibited extreme generalist host-parasitism strategies while other lineages appeared to have been constrained to certain host families over recent evolutionary history. Sequence data from two nuclear genes recovered from a limited sample of Plasmodium parasites indicated that, at the resolution of this study, inferences regarding host breadth were unlikely to be grossly affected by the use of parasite mitochondrial lineages as a proxy for biological species. The use of divergent host-parasitism strategies among closely related parasite lineages suggests that host range is a relatively labile character. Since host specificity may also influence parasite virulence, these results argue for considering the impact of haematozoa on avian hosts on a lineage-specific basis.
在进化框架内，从喀麦隆和加蓬的 527 只鸟类调查中回收的血液寄生虫的宿主特异性在几个层次上进行了检查。从平均 1.3 种（最大为 3 种）和 1.2 个宿主科（最大为 3 个）中回收了 Haemoproteus 的独特线粒体谱系，而从平均 2.5 种（最大为 27 种）和 1.6 个宿主科（最大为 9 种）中回收了 Plasmodium 的谱系。在属内平均，两种寄生虫的谱系在宿主分布方面受到限制，相对于随机预期。然而，尽管两个属内的几个谱系表现出明显的宿主限制，但宿主的广度在相关谱系之间差异很大，尤其是在属 Plasmodium 中。几种 Plasmodium 谱系表现出极端的一般宿主寄生策略，而其他谱系似乎在最近的进化历史中受到某些宿主科的限制。从有限数量的 Plasmodium 寄生虫中回收的两个核基因的序列数据表明，在本研究的分辨率下，关于宿主广度的推断不太可能因使用寄生虫线粒体谱系作为生物物种的替代物而受到严重影响。在密切相关的寄生虫谱系中使用不同的宿主寄生策略表明，宿主范围是一个相对不稳定的特征。由于宿主特异性也可能影响寄生虫的毒力，这些结果表明，有必要考虑寄生虫对鸟类宿主的影响在谱系特异性的基础上。
