Department of Ecology and Evolutionary Biology and Institute of the Environment, University of California, Los Angeles, CA 90095, USA.
Proc Natl Acad Sci U S A. 2012 Jul 17;109(29):11740-5. doi: 10.1073/pnas.1207851109. Epub 2012 Jun 11.
We are unique in reporting a repetition of Bateman [Bateman AJ (1948) Heredity (Edinb) 2:349-368] using his methods of parentage assignment, which linked sex differences in variance of reproductive success and variance in number of mates in small populations of Drosophila melanogaster. Using offspring phenotypes, we inferred who mated with whom and assigned offspring to parents. Like Bateman, we cultured adults expressing dramatic phenotypes, so that each adult was heterozygous-dominant at its unique marker locus but had only wild-type alleles at all other subjects' marker loci. Assuming no viability effects of parental markers on offspring, the frequencies of parental phenotypes in offspring follow mendelian expectations: one-quarter will be double-mutants who inherit the dominant gene from each parent, the offspring from which Bateman counted the number of mates per breeder; half of the offspring must be single mutants inheriting the dominant gene of one parent and the wild-type allele of the other parent; and one-quarter would inherit neither of their parent's marker mutations. Here we show that inviability of double-mutant offspring biased inferences of mate number and number of offspring on which rest inferences of sex differences in fitness variances. Bateman's method overestimated subjects with zero mates, underestimated subjects with one or more mates, and produced systematically biased estimates of offspring number by sex. Bateman's methodology mismeasured fitness variances that are the key variables of sexual selection.
我们使用 Bateman 的亲代分配方法来重复他的研究，这在报告中是独特的，该方法将繁殖成功率的方差和小群体中的果蝇（Drosophila melanogaster）的交配次数的方差联系起来。我们通过后代的表型推断谁与谁交配，并将后代分配给父母。像 Bateman 一样，我们培养表现出明显表型的成虫，使每个成虫在其独特的标记基因座上都是杂合显性的，但在所有其他个体的标记基因座上只有野生型等位基因。假设亲代标记物对后代没有生存能力的影响，那么后代中亲代表型的频率符合孟德尔的预期：四分之一将是双突变体，从每个亲本那里继承了显性基因，Bateman 就是从这些双突变体中计算每个繁殖者的交配次数；一半的后代必须是单突变体，从一个亲本那里继承了显性基因，从另一个亲本那里继承了野生型等位基因；四分之一的后代不会继承他们父母的任何一个标记突变。在这里，我们表明，双突变体后代的生存能力会偏向于交配次数和繁殖后代数量的推断，而这些推断是关于适应性方差的性别差异的基础。Bateman 的方法高估了没有交配的个体，低估了有一个或多个交配的个体，并且对每个性别产生的后代数量产生了系统的偏差估计。Bateman 的方法错误地测量了适应度方差，而适应度方差是性选择的关键变量。
