Genetic loads under fitness-dependent mutation rates
Genetic loads under fitness-dependent mutation rates
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DOI：
10.1046/j.1420-9101.2002.00464.x
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发表时间：
2002-11-01
影响因子：
2.1
通讯作者：
Agrawal, AF
中科院分区：
文献类型：
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作者：
Agrawal, AF
尽管许多理论依赖于有害突变的全基因组率，但对突变率的良好估计很少，而且仍然存在争议。此外，突变率可能不是恒定的，最近的一项研究表明，在轻度压力的环境中，突变率更高。如果突变率是条件的函数，那么携带更多突变的个体往往处于更差的条件，因此产生更多的突变。在这里，我研究了在这种条件依赖的突变率下进化的有性和无性种群的平均适应度。有性种群的均衡平均适应度取决于适应度与突变率的曲线形状。如果突变率随条件增加而协同下降，则平均适应度远低于突变率随条件增加而递减的情况。相比之下，无性种群受条件依赖性突变率的影响较小。无性种群的平衡平均适合度仅取决于负荷最小类中个体的突变率。由于这些个体具有高适应性，因此突变率低，无性种群比有性种群经历更少的遗传负荷，从而增加了性的双重成本。
Although much theory depends on the genome-wide rate of deleterious mutations, good estimates of the mutation rate are scarce and remain controversial. Furthermore, mutation rate may not be constant, and a recent study suggests that mutation rates are higher in mildly stressful environments. If mutation rate is a function of condition, then individuals carrying more mutations will tend to be in worse condition and therefore produce more mutations. Here I examine the mean fitnesses of sexual and asexual populations evolving under such condition-dependent mutation rates. The equilibrium mean fitness of a sexual population depends on the shape of the curve relating fitness to mutation rate. If mutation rate declines synergistically with increasing condition the mean fitness will be much lower than if mutation rate declines at a diminishing rate. In contrast, asexual populations are less affected by condition-dependent mutation rates. The equilibrium mean fitness of an asexual population only depends on the mutation rate of the individuals in the least loaded class. Because such individuals have high fitness and therefore a low mutation rate, asexual populations experience less genetic load than sexual populations, thus increasing the twofold cost of sex.