Barrett Spencer C H
Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada.
Philos Trans R Soc Lond B Biol Sci. 2003 Jun 29;358(1434):991-1004. doi: 10.1098/rstb.2003.1301.
Comparisons of the causes and consequences of cross- and self-fertilization have dominated research on plant mating since Darwin's seminal work on plant reproduction. Here, I provide examples of these accomplishments, but also illustrate new approaches that emphasize the role of floral design and display in pollen dispersal and fitness gain through male function. Wide variation in outcrossing rate characterizes animal-pollinated plants. In species with large floral displays, part of the selfing component of mixed mating can arise from geitonogamy and be maladaptive because of strong inbreeding depression and pollen discounting. Floral strategies that separate the benefits of floral display from the mating costs associated with geitonogamy can resolve these conflicts by reducing lost mating opportunities through male function. The results from experiments with marker genes and floral manipulations provide evidence for the function of herkogamy and dichogamy in reducing self-pollination and promoting pollen dispersal. Evidence is also presented indicating that increased selfing resulting from changes to floral design, or geitonogamy in large clones, can act as a stimulus for the evolution of dioecy. The scope of future research on mating strategies needs to be broadened to include investigations of functional links among flowers, inflorescences and plant architecture within the framework of life-history evolution.
自达尔文关于植物繁殖的开创性著作以来，对异花受精和自花受精的原因及后果的比较一直主导着植物交配研究。在此，我列举了这些研究成果的实例，但也阐述了一些新方法，这些方法强调了花的形态和展示在花粉传播以及通过雄性功能实现适合度增加方面的作用。异交率的广泛差异是动物传粉植物的特征。在具有大型花展示的物种中，混合交配中自交部分的一部分可能源于同株异花授粉，并且由于强烈的近亲繁殖衰退和花粉折扣而具有不良适应性。将花展示的益处与同株异花授粉相关的交配成本区分开来的花策略，可以通过减少雄性功能导致的交配机会损失来解决这些冲突。标记基因实验和花操作实验的结果为雌雄异位和雌雄异熟在减少自花授粉和促进花粉传播方面的功能提供了证据。也有证据表明，花形态变化导致的自交增加，或大型克隆中的同株异花授粉，可作为雌雄异株进化的一种刺激因素。未来交配策略研究的范围需要拓宽，以包括在生活史进化框架内对花、花序和植物结构之间功能联系的研究。
