Charlesworth B, Charlesworth D
Department of Ecology and Evolution, University of Chicago, IL 60637-1573, USA.
Genetica. 1998;102-103(1-6):3-19.
Most mutations with observable phenotypic effects are deleterious. Studies of Drosophila and inbred plant populations suggest that a new individual may have a mean number of new deleterious mutations that exceeds one-half. Most of these have relatively small homozygous effects and reduce fitness by 1-2% when heterozygous. Several striking features of present-day organisms have apparently evolved in response to the constant input of deleterious alleles by recurrent mutation. For example, the adaptations of hermaphroditic organisms for outcrossing have been widely interpreted in terms of the benefits of avoiding the reduced fitness of inbred progeny, which is partly due to deleterious mutations. Population genetic models of modifiers of the breeding system in the presence of genome-wide deleterious mutation are reviewed and their predictions related to genetic and comparative data. The evolution of degenerate Y chromosomes is a phenomenon that may be caused by the accumulation of deleterious mutations. The population genetic mechanisms that can drive this degenerations are reviewed and their significance assessed in the light of available data.
大多数具有可观察到的表型效应的突变都是有害的。对果蝇和自交植物种群的研究表明，一个新个体可能携带的新有害突变的平均数量超过一半。其中大多数具有相对较小的纯合效应，杂合时会使适合度降低1% - 2%。当今生物体的几个显著特征显然是为应对反复突变不断输入有害等位基因而进化出来的。例如，雌雄同体生物为异交所做的适应性改变，已被广泛解释为避免自交后代适合度降低的益处，这部分是由于有害突变所致。本文综述了在全基因组有害突变存在的情况下，繁殖系统修饰因子的群体遗传模型，并阐述了其与遗传数据和比较数据相关的预测。退化Y染色体的进化是一种可能由有害突变积累引起的现象。本文综述了能够推动这种退化的群体遗传机制，并根据现有数据评估了它们的重要性。
