Data from: Frequent and parallel habitat transitions as driver of unbounded radiations in the Cape flora

The enormous species richness in the Cape Floristic Region (CFR) of Southern Africa is the result of numerous radiations, but the temporal progression and possible mechanisms of these radiations are still poorly understood. Here, we explore the macroevolutionary dynamics of the Restionaceae, that include 340 species which are found in all vegetation types in the Cape flora and are ecologically dominant in fynbos. Using an almost complete (i.e. 98%) species-level time calibrated phylogeny and models of diversification dynamics, we show that species diversification is constant through the Cenozoic, with no evidence of an acceleration with the onset of the modern winter-wet climate, or a recent density-dependent slowdown. Contrary to expectation, species inhabiting the oldest (montane) and most extensive (drylands) habitats did not undergo higher diversification rates than species in the younger (lowlands) and more restricted (wetland) habitats. We show that the rate of habitat transitions is more closely related to the speciation rate than to time, and that more than a quarter of all speciation events are associated with habitat transitions. This suggests that the unbounded Restionaceae diversification resulted from numerous, parallel, habitat shifts, rather than persistence in an habitat stimulating speciation. We speculate that this could be one of the mechanisms resulting in the hyper-diverse Cape flora.南非南部的开普植物区（Cape Floristic Region, CFR）拥有极高的物种丰富度，其成因在于多次辐射演化事件，但这类辐射演化的时间进程与潜在机制仍尚未被充分阐明。本次研究聚焦帚灯草科（Restionaceae）的宏观演化动态，该科包含340个物种，遍布开普植物区的所有植被类型，且在凡波斯（fynbos）植被中占据生态主导地位。我们借助覆盖98%物种的近乎完整的物种水平时间校准系统发育树，结合多样化动态模型开展分析，结果显示：新生代以来物种多样化速率始终保持恒定，既未因现代冬季湿润气候的出现而加速，也未出现近期的密度制约型速率放缓。与预期相悖的是，栖息于最古老生境（山地）与最广阔生境（旱地）的类群，其物种形成速率并未高于栖息于较年轻生境（低地）与受限生境（湿地）的类群。研究还发现，生境转换速率与物种形成速率的相关性更强，而非与时间相关；超过四分之一的物种形成事件均伴随生境转换。这表明帚灯草科的无界物种多样化，源于多次平行发生的生境转移，而非类群长期留存于某一特定生境以推动物种形成。我们推测，这一机制或许正是造就开普植物区超高物种多样性的原因之一。