Department of Life Sciences, Centre for Functional Ecology, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
Area of Biodiversity and Conservation, Universidad Rey Juan Carlos, c/Tulipán s/n., Móstoles, Madrid, E-28933, Spain.
New Phytol. 2019 Nov;224(3):1278-1289. doi: 10.1111/nph.15768. Epub 2019 Mar 30.
The evolutionary pathways leading to the heterostylous syndrome are not well understood, and models concerning the origins of distyly differ in the order in which reciprocal herkogamy and self-incompatibility evolve. We investigated the evolution and breakdown of distyly in Plumbaginaceae, a family with considerable diversity of floral traits and reproductive systems. Using Bayesian Markov chain Monte Carlo analyses and stochastic character mapping, we examined the evolutionary assembly and breakdown of the heterostylous syndrome based on a well-resolved phylogeny of 121 species of Plumbaginaceae and six outgroup taxa using five nuclear and plastid gene regions. We used the distribution of reproductive traits and reconstructed ancestral characters across phylogenies to evaluate competing models for the evolution of distyly. The most likely common ancestor of Plumbaginaceae was self-incompatible and monomorphic for sex-organ arrangement and pollen-stigma characters. Character state reconstructions indicated that reciprocal herkogamy evolved at least three times and that shifts to selfing and apomixis occurred on multiple occasions. Our results provide comparative support for the early ideas of H. G. Baker on evolutionary pathways in Plumbaginaceae, and the more recent selfing avoidance model by D. & B. Charlesworth in which distyly evolves from self-incompatible ancestors.
导致异型花柱综合征的进化途径尚不清楚，关于雌雄异位和自交不亲和进化顺序的二型花柱起源模型存在差异。我们研究了 Plumbaginaceae 科异型花柱的进化和崩溃，该科具有相当多样化的花部特征和生殖系统。我们使用贝叶斯马尔可夫链蒙特卡罗分析和随机特征映射，使用五个核和质体基因区域，基于 Plumbaginaceae 科的 121 种和六个外类群的良好分辨率的系统发育，检查了异型花柱综合征的进化组合和崩溃。我们使用生殖特征的分布和跨系统发育重建的祖先特征，评估了二型花柱进化的竞争模型。Plumbaginaceae 科最可能的共同祖先为自交不亲和且雌雄器官排列和花粉柱头特征为单态性。特征状态重建表明，雌雄异位至少进化了三次，自交和无融合生殖的转变发生了多次。我们的结果为 H. G. Baker 在 Plumbaginaceae 科进化途径上的早期观点以及 D. 和 B. Charlesworth 最近的自交回避模型提供了比较支持，该模型认为二型花柱从自交不亲和的祖先进化而来。
