Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.
Department of Forest Management, University of Montana, Missoula, MT, 59802, USA.
Ecol Lett. 2020 Aug;23(8):1223-1231. doi: 10.1111/ele.13522. Epub 2020 May 13.
Offspring polymorphism is a reproductive strategy where individual organisms simultaneously produce offspring that differ in morphology and ecology. It occurs across the Tree of Life but is particularly common among plants, where it is termed seed (diaspore) heteromorphism. The prevalence of this strategy in unpredictably varying environments has resulted in the assumption that it serves as a bet-hedging mechanism. We found 101 examples of this strategy in southwestern North America. We provide phylogenetically informed evidence for the hypothesis that the occurrence of seed heteromorphism increases with increasing environmental variability, though this pattern was only significant for aridity, one of our two rainfall variability metrics. We provide a strong test of bet hedging for a large, taxonomically diverse set of seed heteromorphic species, lending support to the hypothesis that bet hedging is an important mechanistic driver for the evolution of seed heteromorphism.
后代多态性是一种生殖策略，个体生物同时产生在形态和生态上存在差异的后代。它发生在生命之树的各个分支中，但在植物中尤为常见，在植物中被称为种子（胞子）异态现象。这种策略在不可预测的变化环境中很普遍，因此人们假设它是一种风险分散机制。我们在北美西南部发现了 101 个这种策略的例子。我们提供了有系统发育信息的证据，支持种子异态性的发生随着环境变异性的增加而增加的假设，尽管这种模式仅在我们两个降雨变异性度量之一的干旱度方面具有显著意义。我们对大量分类多样的种子异态性物种进行了强有力的风险分散测试，支持了风险分散是种子异态性进化的重要机制驱动因素的假设。
