Evolutionary relationships and biogeography of Biomphalaria (Gastropoda: Planorbidae) with implications regarding its role as host of the human bloodfluke, Schistosoma mansoni
Evolutionary relationships and biogeography of Biomphalaria (Gastropoda: Planorbidae) with implications regarding its role as host of the human bloodfluke, Schistosoma mansoni
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DOI：
10.1093/oxfordjournals.molbev.a003769
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发表时间：
2001-12-01
影响因子：
10.7
通讯作者：
Loker, ES
中科院分区：
文献类型：
--
作者：
DeJong, RJ;Morgan, JAT;Loker, ES
曼氏血吸虫是人类的一种遗传吸虫和寄生虫，其广泛的地理分布是由其中间宿主生物螺属淡水蜗牛的出现决定的（Preston 1910）。利用线粒体16S部分核糖体和ITS1、ITS2完整核苷酸序列对23种生物phalaria、16种新热带和7种非洲血吸虫（包括最重要的血吸虫宿主）进行了系统发育分析。与单独分析数据集相比，通过组合数据集获得了显着更好的分辨率，这表明每个数据集中都存在加性的同余信号。新热带物种是基生的，所有的非洲物种都是衍生的，这表明该属起源于美洲。我们证实，原始的光斑生物phalaria通过跨大西洋的非洲殖民产生了所有的非洲物种。此外，与新热带物种相比，非洲物种之间的遗传距离更小，表明它们的起源更近。有两个物种丰富的分支，一个是以B. glabrata为基础的非洲分支，另一个是新热带分支。在非洲进化支中，分布广泛的热带草原物种，白叶猴和尼罗河物种复合体，都在东非大裂谷的湖泊中定居，并产生了特有的湖泊形式。在新热带进化分支中，曼氏链球菌的两个新获得的自然宿主（B. straminea和B. tenagophila）彼此不是最近的亲戚，这表明两个独立的获得事件。在这两个物种丰富的分支的基础上是几个新热带谱系，它们之间的遗传距离很大，表明在属内存在多个谱系。关于血吸虫的易感性出现了有趣的模式：(1)最易感的宿主属于一个分支，包括B. glabrata和非洲种；(2)几个易感的新热带物种是明显难感染的物种的姐妹群；(3)一些基础谱系是易感的。这些模式表明mansoni存在固有的易感和抗性，但也强调了mansoni适应和获得以前不易感物种作为宿主的能力。schrammi生物phalaria似乎与其他生物phalaria以及Helisoma有远亲关系，可能代表一个单独的或中间的谱系。
The wide geographic distribution of Schistosoma mansoni, a digenetic trematode and parasite of humans, is determined by the occurrence of its intermediate hosts, freshwater snails of the genus Biomphalaria (Preston 1910). We present phylogenetic analyses of 23 species of Biomphalaria, 16 Neotropical and seven African, including the most important schistosome hosts, using partial mitochondrial ribosomal 16S and complete nuclear ribosomal ITS1 and ITS2 nucleotide sequences. A dramatically better resolution was obtained by combining the data sets as opposed to analyzing each separately, indicating that there is additive congruent signal in each data set. Neotropical species are basal, and all African species are derived, suggesting an American origin for the genus. We confirm that a proto-Biomphalaria glabrata gave rise to all African species through a trans Atlantic colonization of Africa. In addition, genetic distances among African species are smaller compared with those among Neotropical species, indicating a more recent origin. There are two species-rich clades, one African with B. glabrata as its base, and the other Neotropical. Within the African clade, a wide-ranging tropical savannah species, B. pfeifferi, and a Nilotic species complex, have both colonized Rift Valley lakes and produced endemic lacustrine forms. Within the Neotropical clade, two newly acquired natural hosts for S. mansoni (B. straminea and B. tenagophila) are not the closest relatives of each other, suggesting two separate acquisition events. Basal to these two species-rich clades are several Neotropical lineages with large genetic distances between them, indicating multiple lineages within the genus. Interesting patterns occur regarding schistosome susceptibility (1) the most susceptible hosts belong to a single clade, comprising B. glabrata and the African species, (2) several susceptible Neotropical species are sister groups to apparently refractory species, and (3) some basal lineages are susceptible. These patterns suggest the existence of both inherent susceptibility and resistance, but also underscore the ability of S. mansoni to adapt to and acquire previously unsusceptible species as hosts. Biomphalaria schrammi appears to be distantly related to other Biomphalaria as well as to Helisoma, and may represent a separate or intermediate lineage.