Kelley Steven E, Clay Keith
Department of Botany, Duke University, Durham, NC, 27706.
Department of Biology, Indiana University, Bloomington, IN, 47405.
Evolution. 1987 Jan;41(1):92-103. doi: 10.1111/j.1558-5646.1987.tb05773.x.
Theoretical models predict that natural selection acting through competitive interactions should lead to increased divergence in resource use and to more equal competitive abilities among different genotypes. The consequent overcompensatory interactions and similar competitive abilities will favor maintenance of genotypic diversity. In field experiments we found that naturally co-occurring genotypes of two perennial grasses, Danthonia spicata and Anthoxanthum odoratum, differed in interspecific competitive performance. The competitive performance of a given genotype often depended on the genotypic identity of the competing species, especially in Danthonia spicata. Both overcompensatory and undercompensatory interactions were found, but neither was prevalent for both species. These data indicate that interactions between species are complex and have an important genetic component. The results from this experiment are compatible with a competitive explanation for the maintenance of genetic variation, but the persistence of weakly competitive genotypes cannot be explained.
理论模型预测，通过竞争相互作用起作用的自然选择应导致资源利用上的差异增加，并使不同基因型之间的竞争能力更加平等。由此产生的超补偿相互作用和相似的竞争能力将有利于基因型多样性的维持。在田间实验中，我们发现两种多年生草本植物——穗三毛（Danthonia spicata）和香茅（Anthoxanthum odoratum）——自然共生的基因型在种间竞争表现上存在差异。给定基因型的竞争表现通常取决于竞争物种的基因型身份，在穗三毛中尤其如此。我们既发现了超补偿相互作用，也发现了欠补偿相互作用，但这两种情况在两个物种中都不普遍。这些数据表明物种间的相互作用是复杂的，并且具有重要的遗传成分。该实验结果与对遗传变异维持的竞争解释相一致，但竞争力较弱的基因型的持续存在无法得到解释。
