Hemmat M, Eggleston P
Department of Genetics and Microbiology, University of Liverpool, U.K.
Heredity (Edinb). 1990 Apr;64 ( Pt 2):223-31. doi: 10.1038/hdy.1990.27.
Despite the importance of competition as an evolutionary determinant in natural populations there have been few studies of the genetical control of competitive ability. Here, we report the results of a biometrical analysis of four continuously varying traits which, between them, describe the competitive interactions in mixed cultures of Drosophila melanogaster. The analysis involved the parental, F1, F2 and backcross generations (including all reciprocals) derived from crosses between two highly inbred lines isolated from the Texas population of D. melanogaster. The competitive performance of each genotype in monoculture and in duoculture with a phenotypically distinct tester were assessed using a yield-density regression analysis. Appropriate genetic models were fitted using a variance weighted least squares procedure and the resulting genetic components of the generation means used to define the genetical architecture of competition. Of the four competitive parameters investigated here the e-value, which describes the competitive performance of the indicator genotype at a fixed reference density, was found to be determined by simple additive genetic effects with no evidence of significant dominance. Conversely, competitive performance in monoculture (intra-genotypic competition) did display a significant net dominance component and the observed values in the F1 and parental generations indicated some degree of heterosis. Of the two competitive parameters determining performance in duoculture (inter-genotypic sensitivity and inter-genotypic pressure) the former was found to have a complex genetic determination involving not only additive and dominance components of the progeny's own genotype but also dominance components of the F1 maternal genotypes. There were also additive-dominance and dominance-dominance non-allelic interactions. Heterosis was evident, determined both by the progeny's own genotype and by one of the F1 maternal genotypes.(ABSTRACT TRUNCATED AT 250 WORDS)
尽管竞争作为自然种群进化决定因素很重要，但对竞争能力的遗传控制却鲜有研究。在此，我们报告了对四个连续变化性状的生物统计学分析结果，这些性状共同描述了黑腹果蝇混合培养中的竞争相互作用。分析涉及从黑腹果蝇德克萨斯种群分离出的两个高度近交系杂交产生的亲代、F1、F2和回交世代（包括所有正反交）。使用产量-密度回归分析评估了每种基因型在单培养以及与表型不同的测试品系进行双培养时的竞争表现。使用方差加权最小二乘法拟合适当的遗传模型，并利用所得世代均值的遗传成分来定义竞争的遗传结构。在这里研究的四个竞争参数中，e值描述了指示基因型在固定参考密度下的竞争表现，发现它由简单的加性遗传效应决定，没有显著显性的证据。相反，单培养中的竞争表现（基因型内竞争）确实显示出显著的净显性成分，F1和亲代世代的观测值表明存在一定程度的杂种优势。在决定双培养表现的两个竞争参数（基因型间敏感性和基因型间压力）中，发现前者具有复杂的遗传决定因素，不仅涉及子代自身基因型的加性和显性成分，还涉及F1母本基因型的显性成分。也存在加性-显性和显性-显性非等位基因相互作用。杂种优势很明显，由子代自身基因型和F1母本基因型之一决定。（摘要截短于250字）
