MULTILOCUS MODELS OF INBREEDING DEPRESSION WITH SYNERGISTIC SELECTION AND PARTIAL SELF-FERTILIZATION
MULTILOCUS MODELS OF INBREEDING DEPRESSION WITH SYNERGISTIC SELECTION AND PARTIAL SELF-FERTILIZATION
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DOI：
10.1017/s0016672300029256
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发表时间：
1991-04-01
期刊：
影响因子：
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通讯作者：
CHARLESWORTH, D
中科院分区：
文献类型：
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作者：
CHARLESWORTH, B;MORGAN, MT;CHARLESWORTH, D
利用有害等位基因突变模型和杂合子优势模型，研究了多基因座适合度控制模型的平均适合度和近交衰退值。假设基因座之间的协同适合性交互作用，以找出这个更生物学上可信的模型是否改变了我们之前使用乘性交互作用模型得到的结论。假设了不连锁的基因座系统。我们使用了确定性的计算机计算，以及基于正态或泊松理论的近似。对于参数空间的某些区域，这些近似与精确结果吻合得很好。在突变模型中，我们发现，与乘性情况相比，协同作用的效果是降低了每个个体的突变等位基因数量，从而提高了平均适应度。然而，近亲交配抑郁的情况有所增加。杂合子优势对平均适合度和近交衰退的影响相似。对于该模型，结果与之前假设的乘性结果定性相似。然而，对于突变负载模型，在高自交率下，随着自交率从零增加，平均适合度有时降低，近交抑制增加。我们还研究了改变自交率的修饰性等位基因的行为，引入平衡种群。一般来说，结果与乘法模型的结果相似，但在某些情况下，存在ESS自交率，其自交率略低于1。最后，我们给出了完全自交种群近亲繁殖衰退的近似表达式。这只取决于突变率和显性系数，因此可以用来估计植物物种对轻度有害等位基因的突变率。
Mean fitness and inbreeding depression values in multi-locus models of the control of fitness were studied, using both a model of mutation to deleterious alleles, and a model of heterozygote advantage. Synergistic fitness interactions between loci were assumed, to find out if this more biologically plausible model altered the conclusions we obtained previously using a model of multiplicative interactions. Systems of unlinked loci were assumed. We used deterministic computer calculations, and approximations based on normal or Poisson theory. These approximations gave good agreement with the exact results for some regions of the parameter space. In the mutational model, we found that the effect of synergism was to lower the number of mutant alleles per individual, and thus to increase the mean fitness, compared with the multiplicative case. Inbreeding depression, however, was increased. Similar effects on mean fitness and inbreeding depression were found for the case of heterozygote advantage. For that model, the results were qualitatively similar to those previously obtained assuming multiplicativity. With the mutational load model, however, the mean fitness sometimes decreased, and the inbreeding depression increased, at high selfing rates, after declining as the selfing rate increased from zero. We also studied the behaviour of modifier alleles tha changed the selfing rate, introduced into equilibrium populations. In general, the results were similar to those with the multiplicative model, but in some cases an ESS selfing rate, with selfing slightly below one, existed. Finally, we derive an approximate expression for the inbreeding depression in completely selfing populations. This depends only on the mutation rate and the dominance coefficient and can therefore be used to obtain estimates of the mutation rate to mildly deleterious alleles for plant species.