Galen Spencer C, Borner Janus, Martinsen Ellen S, Schaer Juliane, Austin Christopher C, West Christopher J, Perkins Susan L
Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th St., New York, NY 10024, USA.
Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th St., New York, NY 10024, USA.
R Soc Open Sci. 2018 May 23;5(5):171780. doi: 10.1098/rsos.171780. eCollection 2018 May.
The evolutionary relationships among the apicomplexan blood pathogens known as the malaria parasites (order Haemosporida), some of which infect nearly 200 million humans each year, has remained a vexing phylogenetic problem due to limitations in taxon sampling, character sampling and the extreme nucleotide base composition biases that are characteristic of this clade. Previous phylogenetic work on the malaria parasites has often lacked sufficient representation of the broad taxonomic diversity within the Haemosporida or the multi-locus sequence data needed to resolve deep evolutionary relationships, rendering our understanding of haemosporidian life-history evolution and the origin of the human malaria parasites incomplete. Here we present the most comprehensive phylogenetic analysis of the malaria parasites conducted to date, using samples from a broad diversity of vertebrate hosts that includes numerous enigmatic and poorly known haemosporidian lineages in addition to genome-wide multi-locus sequence data. We find that if base composition differences were corrected for during phylogenetic analysis, we recovered a well-supported topology indicating that the evolutionary history of the malaria parasites was characterized by a complex series of transitions in life-history strategies and host usage. Notably we find that , the malaria parasite genus that includes the species of human medical concern, is polyphyletic with the life-history traits characteristic of this genus having evolved in a dynamic manner across the phylogeny. We find support for multiple instances of gain and loss of asexual proliferation in host blood cells and production of haemozoin pigment, two traits that have been used for taxonomic classification as well as considered to be important factors for parasite virulence and used as drug targets. Lastly, our analysis illustrates the need for a widespread reassessment of malaria parasite taxonomy.
被称为疟原虫（血孢子虫目）的顶复门血液病原体之间的进化关系一直是个棘手的系统发育问题，因为在分类群抽样、特征抽样方面存在局限性，以及该进化枝特有的极端核苷酸碱基组成偏差。疟原虫先前的系统发育研究往往缺乏对血孢子虫目内广泛分类多样性的充分代表性，或者缺乏解决深层次进化关系所需的多位点序列数据，导致我们对血孢子虫生活史进化和人类疟原虫起源的理解并不完整。在此，我们展示了迄今为止对疟原虫进行的最全面的系统发育分析，使用了来自广泛多样脊椎动物宿主的样本，其中包括众多神秘且鲜为人知的血孢子虫谱系，以及全基因组多位点序列数据。我们发现，如果在系统发育分析过程中校正碱基组成差异，就能得到一个有充分支持的拓扑结构，这表明疟原虫的进化历史具有一系列复杂的生活史策略和宿主使用的转变特征。值得注意的是，我们发现，包括引起人类医学关注的物种的疟原虫属是多系的，该属的生活史特征在整个系统发育中以动态方式进化。我们发现有证据支持宿主血细胞中无性增殖和疟色素产生的多次获得和丧失情况，这两个特征既被用于分类，也被认为是寄生虫毒力的重要因素以及药物靶点。最后，我们的分析表明需要对疟原虫分类进行广泛重新评估。
