Muller's ratchet under epistatic selection.
Muller's ratchet under epistatic selection.
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上位选择下的穆勒棘轮。
DOI：
10.1093/genetics/136.4.1469
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发表时间：
1994
期刊：
影响因子：
3.3
通讯作者：
Kondrashov,AS
中科院分区：
文献类型：
--
作者：
Kondrashov,AS
在一个有限的无性种群中，平均适合度可能会通过一个被称为穆勒棘轮的过程而下降，如果所有具有最小数量有害等位基因的个体都随机丢失，则会发生这种情况。如果这些等位基因对适合度有独立的影响，以前的分析表明，这种下降的速度要么保持不变，要么，如果突变的积累导致人口规模的下降，增长。在这里，我表明，这个结论是相当敏感的独立性假设。如果有害等位基因具有协同适应性效应，那么随着棘轮的推进，最佳可用基因型的频率必然会增加，使其损失的可能性越来越小。因此，足够强的协同上位性可以有效地阻止穆勒棘轮的作用。一个有限的无性种群不会灭绝，而是可以无限地生存下去，尽管平均适应度比没有随机漂移的情况低。
In a finite asexual population mean fitness may decrease by a process known as Muller's ratchet, which proceeds if all individuals with the minimum number of deleterious alleles are randomly lost. If these alleles have independent effects on fitness, previous analysis suggested that the rate of this decrease either remains constant or, if accumulation of mutations leads to the decline of the population size, grows. Here I show that this conclusion is quite sensitive to the assumption of independence. If deleterious alleles have synergistic fitness effects, then, as the ratchet advances, the frequency of the best available genotype will necessarily increase, making its loss less and less probable. As a result, sufficiently strong synergistic epistasis can effectively halt the action of Muller's ratchet. Instead of being driven extinct, a finite asexual population could then survive practically indefinitely, although with lower mean fitness than without random drift.