School of Zoology, University of New South Wales, Kensington, N.S.W., Australia 2033.
Genetics. 1981 May;98(1):199-214. doi: 10.1093/genetics/98.1.199.
Genic variation in male haploids and male diploids was compared assuming constant fitnesses (derived from computer-generated random numbers) and infinite population size. Several models were studied, differing by the fitness correlation between the sexes (r(s)) and genotypes (r(g)), and by the intensity of selection as measured by the coefficient of variation (CV) of the fitness distribution. Genic variation was quantified using the proportion of polymorphic loci, P, the gene diversity at polymorphic loci, H(p), and the gene diversity over all loci, H(a). The two genetic systems were compared via variation ratios: variation in male haploidy/variation in male diploidy.-P and H(a) were markedly lower for male-haploids than for male diploids, the variation ratios declining with increasing r(s), r(g) and CV, but the two genetic systems were similar for H(p). Except for male diploids with r(s) = 1, the two sexes had different equilibrium gene frequencies but the sample sizes required to detect such differences reliably were larger than usually possible in surveys of natural populations.-Data from natural populations fit the above trends qualitatively, but the variation ratios are much lower than those from our analyses, except that for H(p), which is higher when Drosophila is excluded. Also, the frequency distribution of most common alleles from electrophoretic data has a deficiency of intermediate frequencies compared to that from the computer-generated sets of fitnesses, possibly reflecting either the influence of stochastic processes shifting frequencies away from equilibrium or the involvement of alleles under selection-mutation balance.--While electrophoretic data suggest that Drosophila has unusually high levels of genic variation, unusually low levels of genic variation in male haploids compared with male diploids are not strongly indicated. However, if further data confirm male haploids as having low levels of genic variation, likely explanations are that the bulk of electrophoretically detected variation involves fixed-fitness balancing selection, selection-mutation balance involving slightly deleterious recessive alleles, new favorable male haploid alleles moving more rapidly to fixation than under male diploidy and thus carrying linked loci to fixation faster, or some combination of these possible factors.
比较了雄性单倍体和雄性二倍体的基因变异，假设适应度恒定（来自计算机生成的随机数）且群体大小无限。研究了几种模型，这些模型的区别在于性别间（r(s)）和基因型间（r(g)）的适应度相关性以及以适应度分布的变异系数（CV）衡量的选择强度。使用多态性位点的比例（P）、多态性位点的基因多样性（H(p)）和所有位点的基因多样性（H(a)）来量化基因变异。通过变异比来比较两种遗传系统：雄性单倍体的变异/雄性二倍体的变异。-与雄性二倍体相比，雄性单倍体的 P 和 H(a)明显较低，随着 r(s)、r(g)和 CV 的增加，变异比下降，但对于 H(p)，两种遗传系统相似。除了 r(s) = 1 的雄性二倍体之外，两种性别具有不同的平衡基因频率，但在自然种群调查中可靠检测到这些差异所需的样本量大于通常可能获得的。-来自自然种群的数据在定性上符合上述趋势，但除了 H(p)之外，变异比远低于我们分析的结果，而 H(p)则高于排除果蝇时的情况。此外，来自电泳数据的大多数常见等位基因的频率分布与计算机生成的适应度集合的频率分布相比，中间频率不足，这可能反映了随机过程将频率从平衡转移的影响，或者涉及处于选择-突变平衡的等位基因。-虽然电泳数据表明果蝇具有异常高的基因变异水平，但雄性单倍体与雄性二倍体相比，基因变异水平异常低的情况并不明显。然而，如果进一步的数据证实雄性单倍体具有低水平的基因变异，可能的解释是，电泳检测到的大部分变异涉及固定适应度的平衡选择、涉及轻微有害隐性等位基因的选择-突变平衡、新的有利雄性单倍体等位基因比在雄性二倍体下更快地固定，从而更快地将连锁基因座固定，或者这些可能因素的某种组合。
