以早白垩世被子植物大爆发为标志的“陆地革命”和白垩纪末恐龙为代表的生物大灭绝是白垩纪的两个重大事件，它们对陆地生态系统的重新构建和现代化产生了深远的影响。然而，相对木本被子植物而言，草本被子植物的化石比较稀少，导致人们对草本被子植物与这两个事件的联系知之甚少。

近日，植物研究所陈之端研究组及其合作者利用古老的草本被子植物——毛茛科作为代表研究了以草本被子植物占优势的植被的进化。研究人员发现现存的毛茛科植物起源于白垩纪中期的森林中，早期分化出的三个支系均为林下成分；在白垩纪晚期发生了快速辐射，即在14百万年甚至1~2百万年之内出现了11个支系，其中7个支系是分布在开放的生境中。多样化分析进一步显示毛茛科植物在相同的时间段发生了多样化速率的升高。由此，研究人员认为以草本被子植物占优势的林下草本层与以被子植物占优势的森林的兴起是同步的，共同对白垩纪“陆地革命”做出了贡献，而开放生境中以草本被子植物占优势的植被则稍晚于森林的形成，或者在森林形成末期才兴起。同时，根据毛茛科植物多样化速率在白垩纪-古近纪交界没有发生明显变化，认为以草本被子植物占优势的植被受白垩纪末大灭绝事件影响较小。

该研究结果阐明了林下草本层和开放生境中草本植被的形成时间，明确了不同生境中草本被子植物对白垩纪“陆地革命”的参与时间；同时，揭示了草本被子植物对白垩纪末大灭绝事情的响应。研究结果对于理解陆地植被的演化、组建具有重要意义。相关成果于6月2日发表在《科学报告》上。（来源：科学网）

The rise of angiosperm-dominated herbaceous floras: Insights from Ranunculaceae

The rise of angiosperms has been regarded as a trigger for the Cretaceous revolution of terrestrial ecosystems. However, the timeframe of the rise angiosperm-dominated herbaceous floras (ADHFs) is lacking. Here, we used the buttercup family (Ranunculaceae) as a proxy to provide insights into the rise of ADHFs. An integration of phylogenetic, molecular dating, ancestral state inferring, and diversification analytical methods was used to infer the early evolutionary history of Ranunculaceae. We found that Ranunculaceae became differentiated in forests between about 108–90 Ma. Diversification rates markedly elevated during the Campanian, mainly resulted from the rapid divergence of the non-forest lineages, but did not change across the Cretaceous-Paleogene boundary. Our data for Ranunculaceae indicate that forest-dwelling ADHFs may have appeared almost simultaneously with angiosperm-dominated forests during the mid-Cretaceous, whereas non-forest ADHFs arose later, by the end of the Cretaceous terrestrial revolution. Furthermore, ADHFs were relatively unaffected by the Cretaceous-Paleogene mass extinction.

原文链接：http://www.nature.com/articles/srep27259