Sabath Niv, Goldberg Emma E, Glick Lior, Einhorn Moshe, Ashman Tia-Lynn, Ming Ray, Otto Sarah P, Vamosi Jana C, Mayrose Itay
Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, Israel.
Department of Ecology, Evolution & Behavior, University of Minnesota, St Paul, MN, 55108-6097, USA.
New Phytol. 2016 Feb;209(3):1290-300. doi: 10.1111/nph.13696. Epub 2015 Oct 15.
Dioecy, the sexual system in which male and female organs are found in separate individuals, allows greater specialization for sex-specific functions and can be advantageous under various ecological and environmental conditions. However, dioecy is rare among flowering plants. Previous studies identified contradictory trends regarding the relative diversification rates of dioecious lineages vs their nondioecious counterparts, depending on the methods and data used. We gathered detailed species-level data for dozens of genera that contain both dioecious and nondioecious species. We then applied a probabilistic approach that accounts for differential speciation, extinction, and transition rates between states to examine whether there is an association between dioecy and lineage diversification. We found a bimodal distribution, whereby dioecious lineages exhibited higher diversification in certain genera but lower diversification in others. Additional analyses did not uncover an ecological or life history trait that could explain a context-dependent effect of dioecy on diversification. Furthermore, in-depth simulations of neutral characters demonstrated that such bimodality is also found when simulating neutral characters across the observed trees. Our analyses suggest that - at least for these genera with the currently available data - dioecy neither consistently places a strong brake on diversification nor is a strong driver.
雌雄异株是一种性别系统，即雄性和雌性器官分别存在于不同个体中，它能使性别特异性功能实现更高程度的特化，并且在各种生态和环境条件下可能具有优势。然而，雌雄异株在开花植物中较为罕见。以往的研究根据所使用的方法和数据，在雌雄异株谱系与其非雌雄异株对应谱系的相对多样化速率方面发现了相互矛盾的趋势。我们收集了包含雌雄异株和非雌雄异株物种的数十个属的详细物种水平数据。然后，我们应用了一种概率方法，该方法考虑了不同状态之间的物种形成、灭绝和转变速率，以研究雌雄异株与谱系多样化之间是否存在关联。我们发现了一种双峰分布，即雌雄异株谱系在某些属中表现出较高的多样化，但在其他属中则较低。进一步的分析没有发现能够解释雌雄异株对多样化的背景依赖性影响的生态或生活史特征。此外，对中性性状的深入模拟表明，在跨观察到的树木模拟中性性状时也会发现这种双峰性。我们的分析表明，至少对于这些拥有当前可用数据的属来说，雌雄异株既不会始终对多样化产生强烈的抑制作用，也不是一个强大的驱动因素。
