Hedrick Philip W
Department of Biology, Arizona State University, Tempe 85287-1501, USA.
Evolution. 2002 Mar;56(3):654-7. doi: 10.1111/j.0014-3820.2002.tb01374.x.
It has been assumed, based on theoretical studies, that lethals with the level of dominance estimated from experimental studies would have an allele frequency that is virtually independent of effective population size. However, here it is shown numerically that the expected frequency of lethals with low levels of dominance is also dependent on finite population size, although not as much as completely recessive lethals. This finding is significant in determining the standing level of inbreeding depression and the consequent potential for the evolution of self-fertilization. In addition, the architecture of genetic variation influencing inbreeding depression in populations with a history of small size may be of important consequence in endangered species. Finally, it is shown that the loss of lethal genetic variation often occurs much more quickly than the regeneration of lethal variation by mutation. This asymmetry may result in a lower standing genetic variation for inbreeding depression than expected from mutation rates and contemporary population size data.
基于理论研究，人们假定，根据实验研究估算出具有一定显性水平的致死基因，其等位基因频率实际上与有效种群大小无关。然而，本文通过数值计算表明，具有低显性水平的致死基因的预期频率也取决于有限的种群大小，尽管其受影响程度不如完全隐性致死基因那么大。这一发现对于确定近亲繁殖衰退的现有水平以及随之而来的自体受精进化潜力具有重要意义。此外，在经历过小规模种群历史的种群中，影响近亲繁殖衰退的遗传变异结构可能对濒危物种具有重要影响。最后，研究表明，致死基因变异的丧失通常比通过突变产生致死变异的速度快得多。这种不对称性可能导致近亲繁殖衰退的现有遗传变异低于根据突变率和当代种群大小数据所预期的水平。
