Tank David C, Eastman Jonathan M, Pennell Matthew W, Soltis Pamela S, Soltis Douglas E, Hinchliff Cody E, Brown Joseph W, Sessa Emily B, Harmon Luke J
Department of Biological Sciences, University of Idaho, Moscow, ID, 83844, USA.
Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID, 83844, USA.
New Phytol. 2015 Jul;207(2):454-467. doi: 10.1111/nph.13491. Epub 2015 Jun 4.
Our growing understanding of the plant tree of life provides a novel opportunity to uncover the major drivers of angiosperm diversity. Using a time-calibrated phylogeny, we characterized hot and cold spots of lineage diversification across the angiosperm tree of life by modeling evolutionary diversification using stepwise AIC (MEDUSA). We also tested the whole-genome duplication (WGD) radiation lag-time model, which postulates that increases in diversification tend to lag behind established WGD events. Diversification rates have been incredibly heterogeneous throughout the evolutionary history of angiosperms and reveal a pattern of 'nested radiations' - increases in net diversification nested within other radiations. This pattern in turn generates a negative relationship between clade age and diversity across both families and orders. We suggest that stochastically changing diversification rates across the phylogeny explain these patterns. Finally, we demonstrate significant statistical support for the WGD radiation lag-time model. Across angiosperms, nested shifts in diversification led to an overall increasing rate of net diversification and declining relative extinction rates through time. These diversification shifts are only rarely perfectly associated with WGD events, but commonly follow them after a lag period.
我们对植物生命之树的认识不断加深，这为揭示被子植物多样性的主要驱动因素提供了新的契机。利用一个经过时间校准的系统发育树，我们通过使用逐步AIC（MEDUSA）对进化多样化进行建模，描绘了整个被子植物生命之树中谱系多样化的热点和冷点。我们还测试了全基因组复制（WGD）辐射滞后时间模型，该模型假定多样化的增加往往滞后于既定的WGD事件。在被子植物的整个进化历史中，多样化速率一直存在着令人难以置信的异质性，并揭示出一种“嵌套辐射”模式——净多样化的增加嵌套在其他辐射之中。这种模式反过来又在科和目层面上产生了分支年龄与多样性之间的负相关关系。我们认为，系统发育中随机变化的多样化速率解释了这些模式。最后，我们证明了WGD辐射滞后时间模型具有显著的统计学支持。在整个被子植物中，多样化的嵌套式转变导致净多样化速率总体上升，相对灭绝速率随时间下降。这些多样化转变很少与WGD事件完全相关，但通常在滞后一段时间后随之发生。
