Genetic drift at expanding frontiers promotes gene segregation
Genetic drift at expanding frontiers promotes gene segregation
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DOI：
10.1073/pnas.0710150104
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发表时间：
2007-12-11
影响因子：
11.1
通讯作者：
Nelson, David R.
中科院分区：
文献类型：
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作者：
Hallatschek, Oskar;Hersen, Pascal;Nelson, David R.
随机遗传漂移和自然选择之间的竞争在进化中发挥着核心作用：虽然无益的突变通常在小种群中偶然占上风，但席卷大种群的突变通常会带来选择性优势。然而，在这里，我们观察到了范围扩大期间的偶然效应，这种效应即使在大型微生物种群中也会显著改变基因库。最初，两株荧光标记的大肠杆菌菌株很好地混合在一起，形成了定义良好的扇形区域，在不断扩大的菌落中具有分形边界。这些区域的形成是由随机波动驱动的，这些随机波动起源于不断扩大的前沿的一小群先驱者。对细菌和酵母菌落(酿酒酵母)的比较表明，这种大规模的遗传扇区划分是一种普遍现象，可能会提供过去范围扩展的可检测足迹。
Competition between random genetic drift and natural selection play a central role in evolution: Whereas nonbeneficial mutations often prevail in small populations by chance, mutations that sweep through large populations typically confer a selective advantage. Here, however, we observe chance effects during range expansions that dramatically alter the gene pool even in large microbial populations. Initially well mixed populations of two fluorescently labeled strains of Escherichia coli develop well defined, sector-like regions with fractal boundaries in expanding colonies. The formation of these regions is driven by random fluctuations that originate in a thin band of pioneers at the expanding frontier. A comparison of bacterial and yeast colonies (Saccharomyces cerevisiae) suggests that this large-scale genetic sectoring is a generic phenomenon that may provide a detectable footprint of past range expansions.