Multiple reproductive barriers separate recently diverged sunflower ecotypes

Measuring reproductive barriers between groups of organisms is an effective way to determine the traits and mechanisms that impede gene flow. However, to understand the ecological and evolutionary factors that drive speciation, it is important to distinguish between the barriers that arise early in the speciation process and those that arise after speciation is largely complete. In this paper we comprehensively test for reproductive isolation between recently diverged (< 10,000 years bp) dune and non-dune ecotypes of the prairie sunflower, Helianthus petiolaris. We find reproductive barriers acting at multiple stages of hybridization, including premating, postmating-prezygotic, and postzygotic barriers, despite the recent divergence. Barriers include extrinsic selection against immigrants and hybrids, a shift in pollinator assemblage, and post-pollination assortative mating. Together these data suggest that multiple barriers can be important for reducing gene flow in the earliest sta...

检测不同类群生物间的生殖隔离屏障（reproductive barriers），是明确阻碍基因流（gene flow）的性状与机制的有效途径。然而，若要阐明驱动物种形成（speciation）的生态与演化因素，则需区分物种形成早期产生的隔离屏障与物种形成基本完成后才出现的隔离屏障。本研究针对分化时间距今不足1万年（<10000年 bp）的草原向日葵（Helianthus petiolaris）的沙丘与非沙丘生境生态型（ecotype），全面检测了二者间的生殖隔离情况。尽管二者分化时间极短，我们仍发现杂交过程多个阶段均存在生殖隔离屏障，包括交配前隔离、交配后合子前隔离与合子后隔离（premating, postmating-prezygotic, and postzygotic barriers）。这些隔离屏障包括对迁入个体与杂交后代的外源选择、传粉者类群组成的转变，以及授粉后选型交配。综合上述数据表明，在物种形成的最早阶