Département d'Ecologie et Evolution, Université de Lausanne, Biophore, UNIL-Sorge, 1015 Lausanne, Switzerland.
Malar J. 2012 Feb 22;11:53. doi: 10.1186/1475-2875-11-53.
The majority of Haemosporida species infect birds or reptiles, but many important genera, including Plasmodium, infect mammals. Dipteran vectors shared by avian, reptilian and mammalian Haemosporida, suggest multiple invasions of Mammalia during haemosporidian evolution; yet, phylogenetic analyses have detected only a single invasion event. Until now, several important mammal-infecting genera have been absent in these analyses. This study focuses on the evolutionary origin of Polychromophilus, a unique malaria genus that only infects bats (Microchiroptera) and is transmitted by bat flies (Nycteribiidae).
Two species of Polychromophilus were obtained from wild bats caught in Switzerland. These were molecularly characterized using four genes (asl, clpc, coI, cytb) from the three different genomes (nucleus, apicoplast, mitochondrion). These data were then combined with data of 60 taxa of Haemosporida available in GenBank. Bayesian inference, maximum likelihood and a range of rooting methods were used to test specific hypotheses concerning the phylogenetic relationships between Polychromophilus and the other haemosporidian genera.
The Polychromophilus melanipherus and Polychromophilus murinus samples show genetically distinct patterns and group according to species. The Bayesian tree topology suggests that the monophyletic clade of Polychromophilus falls within the avian/saurian clade of Plasmodium and directed hypothesis testing confirms the Plasmodium origin.
Polychromophilus' ancestor was most likely a bird- or reptile-infecting Plasmodium before it switched to bats. The invasion of mammals as hosts has, therefore, not been a unique event in the evolutionary history of Haemosporida, despite the suspected costs of adapting to a new host. This was, moreover, accompanied by a switch in dipteran host.
大多数 Haemosporida 物种感染鸟类或爬行动物，但许多重要属，包括 Plasmodium，感染哺乳动物。血孢子虫的双翅目媒介在鸟类、爬行动物和哺乳动物 Haemosporida 中共享，这表明血孢子虫进化过程中哺乳动物发生了多次入侵；然而，系统发育分析仅检测到一次入侵事件。到目前为止，这些分析中还缺少几个重要的哺乳动物感染属。本研究专注于 Polychromophilus 的进化起源，这是一个独特的疟疾属，仅感染蝙蝠（Microchiroptera），并由蝙蝠蝇（Nycteribiidae）传播。
从瑞士捕获的野生蝙蝠中获得了两种 Polychromophilus 物种。使用来自三个不同基因组（核、质体、线粒体）的四个基因（asl、clpc、coI、cytb）对这些物种进行了分子特征分析。然后将这些数据与 GenBank 中可用的 60 种 Haemosporida 数据相结合。使用贝叶斯推断、最大似然法和一系列生根方法来测试 Polychromophilus 与其他血孢子虫属之间的系统发育关系的具体假设。
Polychromophilus melanipherus 和 Polychromophilus murinus 样本显示出基因上明显不同的模式，并根据物种分组。贝叶斯树拓扑结构表明，单系的 Polychromophilus 类群属于鸟类/爬行动物的 Plasmodium 类群，定向假设检验证实了 Plasmodium 的起源。
Polychromophilus 的祖先很可能是一种感染鸟类或爬行动物的 Plasmodium，然后才转而感染蝙蝠。因此，尽管适应新宿主的成本很高，但哺乳动物作为宿主的入侵在 Haemosporida 的进化历史中并不是一个独特的事件。此外，这伴随着双翅目宿主的转变。
