On the complexity of triggering evolutionary radiations

Recent developments in phylogenetic methods have made it possible to reconstruct evolutionary radiations from extant taxa, but identifying the triggers of radiations is still problematic. Here, we propose a conceptual framework to explore the role of variables that may impact radiations. We classify the variables into extrinsic conditions vs intrinsic traits, whether they provide background conditions, trigger the radiation, or modulate the radiation. We used three clades representing angiosperm phylogenetic and structural diversity (Ericaceae, Fagales and Poales) as test groups. We located radiation events, selected variables potentially associated with diversification, and inferred the temporal sequences of evolution. We found 13 shifts in diversification regimes in the three clades. We classified the associated variables, and determined whether they originated before the relevant radiation (backgrounds), originated simultaneously with the radiations (triggers), or evolved later (modu...系统发育方法（phylogenetic methods）的最新进展已使得从现生类群（extant taxa）中重建进化辐射（evolutionary radiation）成为可能，但明确辐射事件的触发因素仍存在疑难。本研究提出一套概念框架，用以探究可能影响进化辐射的各类变量的作用机制。我们将这些变量划分为外在环境条件与内在性状两大类，并依据其功能分为提供背景条件、触发辐射事件或调控辐射进程三类。我们选取三类代表被子植物（angiosperm）系统发育与结构多样性的演化支（clade）——杜鹃花科（Ericaceae）、壳斗目（Fagales）和禾本目（Poales）——作为测试类群。我们定位了辐射事件位点，筛选出可能与物种分化（diversification）相关的变量，并推演了演化的时间序列。本研究在三个演化支中共发现13次物种分化制度（diversification regime）的转变，并对关联变量进行了分类，同时判定这些变量是在对应辐射事件发生前（作为背景条件）、与辐射事件同步起源（作为触发因素），还是在之后逐步演化形成（调控……