Meagher Thomas R
Department of Biological Sciences, Rutgers University, P.O. Box 1059, Piscataway, NJ, 08855-1059, USA.
Evolution. 1992 Apr;46(2):445-457. doi: 10.1111/j.1558-5646.1992.tb02050.x.
It is widely recognized that there are basic conflicts between the resource needs of a plant for paternal versus maternal functions. In dioecious species, these divergent demands, and the selection pressures they impose, can lead to the evolution of sexual dimorphism. The present study was conducted to assess the potential for the evolution of sexual dimorphism in Silene latifolia by evaluating the genetic variation and genetic correlation between characters and between the sexes for a range of growth and reproductive characters. Sexual dimorphism is largely restricted to reproductive characters, particularly flower number and flower size. A canonical correlation analysis revealed considerable intercorrelation between growth characters, such as germination date, height, and leaf size, and reproductive characters; plants that grow fast early on also flower earlier, and plants that produce big leaves also produce big flowers. There was genetic variation for several sexually dimorphic characters; much of the focus in this analysis was on flower size, particularly calyx diameter. Finally, genetic correlations within and between the sexes were found that limit the rate of evolutionary divergence between the sexes. The genetic results suggest that S. latifolia has been subject to divergent selection on the two sexes for a long period of time, bringing about a gradual fixation of sex-limited gene effects, so that the remaining genetic effects are expressed in both sexes. Genetic correlations between the sexes that arise from this residual variation impose limits on further evolutionary change.
人们普遍认识到，植物在父本功能与母本功能的资源需求之间存在基本冲突。在雌雄异株物种中，这些不同的需求以及它们所施加的选择压力会导致两性异形的进化。本研究旨在通过评估一系列生长和生殖性状在性状之间以及性别之间的遗传变异和遗传相关性，来评估宽叶蝇子草两性异形进化的潜力。两性异形在很大程度上仅限于生殖性状，特别是花的数量和大小。典型相关分析揭示了生长性状（如发芽日期、高度和叶片大小）与生殖性状之间存在相当大的相互关联；早期生长快的植物开花也早，叶片大的植物花朵也大。几个两性异形性状存在遗传变异；该分析的重点大多放在花的大小上，特别是花萼直径。最后，发现了性别内部和性别之间的遗传相关性，这些相关性限制了两性之间进化分歧的速率。遗传结果表明，宽叶蝇子草长期以来在两性上受到不同的选择，导致性别限制基因效应逐渐固定，从而使其余的遗传效应在两性中都得以表达。由这种剩余变异产生的性别之间的遗传相关性对进一步的进化变化施加了限制。
