Evidence for genetic drift in the diversification of a geographically isolated population of the hyperthermophilic archaeon Pyrococcus
Evidence for genetic drift in the diversification of a geographically isolated population of the hyperthermophilic archaeon Pyrococcus
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DOI：
10.1093/molbev/msi227
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发表时间：
2005-11-01
影响因子：
10.7
通讯作者：
DiRuggiero, J
中科院分区：
文献类型：
--
作者：
Escobar-Páramo, P;Ghosh, S;DiRuggiero, J
遗传漂变是种群分化的一种机制，在动植物进化中很重要，但在自由生活的微生物中被认为是罕见的，因为它们通常有很大的种群规模和不受限制的传播方式。我们使用系统发育和插入序列（IS）元素分析在超嗜热古菌属Pyrococcus测试的假设，遗传漂变发挥了重要作用，这些微生物的多样化。多位点序列分型收集的36株热球菌，从不同的热液系统在太平洋和地中海，揭示了不同地理位置的热球菌种群的遗传分化。在这些分离株中的IS元素的分析暴露了他们的存在，在所有个人的只有一个地理上孤立的血统，即在地中海的Vulcano岛。对Vulcano群体中6个选定的IS元件进行的详细序列分析表明，这些元件会导致有害的基因组改变，包括基因功能的失活。高频率的IS元素在采样的人口与他们观察到的有害影响的基因组中的火球菌提供分子证据表明，火山岛人口的火球菌地理隔离，这些遗传移动的元素已被带到高频率的遗传漂变。因此，物理隔离导致的遗传漂变应被视为原核生物分化的一个影响因素。
Genetic drift is a mechanism of population divergence that is important in the evolution of plants and animals but is thought to be rare in free-living microorganisms because of their typically large population sizes and unrestricted means of dispersal. We used both phylogenetic and insertion sequence (IS) element analyses in hyperthermophilic archaea of the genus Pyrococcus to test the hypothesis that genetic drift played an important role in the diversification of these microorganisms. Multilocus sequence typing of a collection of 36 isolates of Pyrococcus, from different hydrothermal systems in the Pacific Ocean and the Mediterranean Sea, revealed that Pyrococcus populations from different geographic locations are genetically differentiated. Analysis of IS elements in these isolates exposed their presence in all individuals of only one geographically isolated lineage, that of Vulcano Island in the Mediterranean Sea. Detailed sequence analysis of six selected IS elements in the Vulcano population showed that these elements cause deleterious genomic alterations, including inactivation of gene function. The high frequency of IS elements in the sampled population together with their observed harmful effects in the genome of Pyrococcus provide molecular evidence that the Vulcano Island population of Pyrococcus is geographically isolated and that those genetic mobile elements have been brought up to high frequency by genetic drift. Thus, genetic drift resulting from physical isolation should be considered as a factor influencing differentiation in prokaryotes.