Malaria's eve:: Evidence of a recent population bottleneck throughout the world populations of Plasmodium falciparum
Malaria's eve:: Evidence of a recent population bottleneck throughout the world populations of Plasmodium falciparum
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DOI：
10.1073/pnas.95.8.4425
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发表时间：
1998-04-14
影响因子：
11.1
通讯作者：
Ayala, FJ
中科院分区：
文献类型：
--
作者：
Rich, SM;Light, MC;Ayala, FJ
我们分析了全球恶性疟原虫地理株的DNA序列，发现在10个基因位点完全不存在同义DNA多态性。我们假设，所有现存的世界种群的寄生虫最近（几千年内）来自一个单一的祖先菌株。这个最近的共同祖先生活的时间的95%置信区间的上限是在24，500和57，500西尔斯之间（取决于对核苷酸替换率的不同估计）;实际时间可能要近得多。恶性疟原虫种群的近期起源可能是由于人口大扫荡（恶性疟原虫只是最近才从一个地理上有限的小种群扩散到世界各地）或选择性扫荡（自然选择所青睐的一种菌株最近取代了所有其他菌株）。选择性横扫假说要求恶性疟原虫的种群是有效的克隆，尽管寄生虫生命周期的专性有性阶段。几千年前开始的人口普查与最后一次冰川期后的全球气候变化、蚊子媒介的嗜蚊性增加以及农业的传播是一致的。恶性疟原虫可能只是在过去的6,000年里才从非洲热带起源迅速传播到世界的热带和亚热带地区。恶性疟原虫是人类最恶性的疟原虫，其毒力可能与近年来世界范围内恶性疟原虫种群的起源有关。
We have analyzed DNA sequences from world-wide geographic strains of Plasmodium falciparum and found a complete absence of synonymous DNA polymorphism at 10 gene loci. We hypothesize that all extant world populations of the parasite have recently derived (within several thousand years) from a single ancestral strain. The upper limit of the 95% confidence interval for the time when this most recent common ancestor lived is between 24,500 and 57,500 Sears ago (depending on different estimates of the nucleotide substitution rate); the actual time is likely to be much more recent. The recent origin of the P. falciparum populations could have resulted from either a demographic sweep (P. falciparum has only recently spread throughout the world from a small geographically confined population) or a selective sweep (one strain favored by natural selection has recently replaced all others). The selective sweep hypothesis requires that populations of P. falciparum be effectively clonal, despite the obligate sexual stage of the parasite life cycle. A demographic sweep that started several thousand Sears ago is consistent with worldwide climatic changes ensuing the last glaciation, increased anthropophilia of the mosquito vectors, and the spread of agriculture. P. falciparum may have rapidly spread from its African tropical origins to the tropical and subtropical regions of the world only within the last 6,000 years. The recent origin of the world-wide P. falciparum populations may account for its virulence, as the most malignant of human malarial parasites.