Käfer Jos, Marais Gabriel A B, Pannell John R
Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Lyon 1, Bât. Grégor Mendel 43, bd du 11 novembre 1918, 69622, Villeurbanne cedex, France.
Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.
Mol Ecol. 2017 Mar;26(5):1225-1241. doi: 10.1111/mec.14020. Epub 2017 Feb 8.
Dioecy, the coexistence of separate male and female individuals in a population, is a rare but phylogenetically widespread sexual system in flowering plants. While research has concentrated on why and how dioecy evolves from hermaphroditism, the question of why dioecy is rare, despite repeated transitions to it, has received much less attention. Previous phylogenetic and theoretical studies have suggested that dioecy might be an evolutionary dead end. However, recent research indicates that the phylogenetic support for this hypothesis is attributable to a methodological bias and that there is no evidence for reduced diversification in dioecious angiosperms. The relative rarity of dioecy thus remains a puzzle. Here, we review evidence for the hypothesis that dioecy might be rare not because it is an evolutionary dead end, but rather because it easily reverts to hermaphroditism. We review what is known about transitions between hermaphroditism and dioecy, and conclude that there is an important need to consider more widely the possibility of transitions away from dioecy, both from an empirical and a theoretical point of view, and by combining tools from molecular evolution and insights from ecology.
雌雄异株，即种群中雄性和雌性个体分开存在的现象，是开花植物中一种罕见但在系统发育上广泛存在的性系统。虽然研究集中在雌雄异株为何以及如何从雌雄同体进化而来，但尽管多次向雌雄异株转变，雌雄异株为何罕见的问题却很少受到关注。先前的系统发育和理论研究表明，雌雄异株可能是一个进化死胡同。然而，最近的研究表明，对这一假设的系统发育支持归因于方法上的偏差，而且没有证据表明雌雄异株的被子植物的多样化有所减少。因此，雌雄异株相对罕见仍然是一个谜。在这里，我们回顾了这样一个假设的证据，即雌雄异株可能罕见并非因为它是一个进化死胡同，而是因为它很容易恢复为雌雄同体。我们回顾了关于雌雄同体和雌雄异株之间转变的已知情况，并得出结论，从经验和理论角度，以及通过结合分子进化工具和生态学见解，都迫切需要更广泛地考虑从雌雄异株转变出去的可能性。
