Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, E-28933 Móstoles, Spain.
Am J Bot. 2009 May;96(5):1011-9. doi: 10.3732/ajb.0800231. Epub 2009 Apr 16.
From an ancestor with bisexual flowers, plants with unisexual flowers, or even unisexual individuals have evolved in different lineages of angiosperms. The Asteraceae tribe Inuleae includes hermaphroditic, monoecious, dioecious, and gynomonoecious species. Gynomonoecy, the sexual system in which female and bisexual flowers occur on the same plant, is prevalent in the Asteraceae. We inferred one large gene phylogeny (ndhF) and two supertrees to investigate whether gynomonoecy was a stage in the evolution from hermaphroditism to monoecy. We identified transitions in sexual system evolution using the stochastic character mapping method. From gynomonoecious ancestors, both hermaphroditic and monoecious descendants have evolved. Gynomonoecy was not restricted to a stage in the evolution toward monoecy because the number of transitions and the rate of change from monoecy to gynomonoecy were much higher than the opposite. We also investigated one hypothesized association among female flowers and the development of a petaloid ray as an explanation of gynomonoecy maintenance in Asteraceae. We found that peripheral female flowers and petaloid rays were phylogenetically correlated. However, empirical evidence shows that a causal relationship between these traits is not clear.
从具有两性花的祖先、具有单性花的祖先，甚至具有单性花的个体，在被子植物的不同谱系中进化而来。菊科菊苣族包括雌雄同体、雌雄同株、雌雄异株和雌全同株的物种。雌全同株是指在同一植株上同时出现雌性和两性花的性系统，在菊科中很普遍。我们推断了一个大的基因系统发育（ndhF）和两个超级树，以调查雌全同株是否是从雌雄同体到雌雄异株进化的一个阶段。我们使用随机特征映射方法识别性系统进化中的转变。从雌全同株的祖先，同时进化出了雌雄同体和雌雄异株的后代。雌全同株并不仅限于向雌雄异株进化的一个阶段，因为从雌雄异株到雌全同株的转变数量和变化速度都远高于相反的情况。我们还研究了一个关于雌性花和瓣状射线发育之间的假设关联，以解释菊科中雌全同株的维持。我们发现，外围的雌性花和瓣状射线在系统发育上是相关的。然而，实证证据表明，这些特征之间的因果关系并不清楚。
