Data from: Evolutionary radiations of Proteaceae are triggered by the interaction between traits and climates in open habitats

Aim: Ecologically driven diversification can create spectacular diversity in both species numbers and form. However, the prediction that the match between intrinsic (e.g. functional trait) and extrinsic (e.g. climatic niche) variables may lead to evolutionary radiation has not been critically tested. Here, we test this hypothesis in the Southern Hemisphere plant family Proteaceae, which shows a spectacular diversity in open mediterranean shrublands in the Southwest Australian Floristic Region (SWAFR) and the Cape Floristic Region (CFR). Species in the Proteaceae family occupy habitats ranging from tropical rain forests to deserts and are remarkably variable in leaf morphology. Location: Southern Hemisphere. Methods: We built a phylogenetic tree for 337 Proteaceae species (21% of the total), representing all main clades, climatic tolerances and morphologies, and collected leaf functional traits (leaf area, sclerophylly, leaf shape) for 261 species and climatic niche data for 1645 species. Phylogenetic generalized least squares regression and quantitative-trait evolutionary model testing were used to investigate the evolutionary pathways of traits and climatic niches, and their effect on diversification rates. Results: We found that divergent selection may have caused lineages in open vegetation types to evolve towards trait and climatic niche optima distinct from those in closed forests. Furthermore, we show that the interaction between open habitats, dry, warm and/or mediterranean climates, and small, sclerophyllous, toothed leaves increases net diversification rates in Proteaceae. Main conclusions: Our results suggest that the evolution of specific leaf adaptations may have allowed Proteaceae to adapt to variable climatic niches and diversify extensively in open ecosystems such as those in the CFR and SWAFR. This match between morphology and environment may therefore more generally lead to evolutionary radiation.

研究目的：生态驱动的物种分化可造就物种数量与形态的惊人多样性。然而，"内在变量（如功能性状（functional trait））与外在变量（如气候生态位（climatic niche））的匹配可引发进化辐射（evolutionary radiation）"这一假说尚未得到严格检验。本研究以南半球山龙眼科（Proteaceae）为研究对象，该科植物在西南澳大利亚植物区（Southwest Australian Floristic Region，SWAFR）与开普植物区（Cape Floristic Region，CFR）的开阔地中海灌丛中展现出极高的物种多样性。山龙眼科植物的生境跨度从热带雨林至沙漠，叶形态变异极为显著。
研究区域：南半球。
研究方法：我们构建了涵盖337种山龙眼科植物（占总物种数的21%）的系统发育树（phylogenetic tree），该样本覆盖了所有主要演化支（clade）、气候耐受类型与形态类型；并收集了261个物种的叶片功能性状数据，包括叶面积、硬叶性（sclerophylly）与叶形，同时获取了1645个物种的气候生态位数据。本研究采用系统发育广义最小二乘回归（phylogenetic generalized least squares regression）与数量性状进化模型检验方法，探究性状与气候生态位的演化路径及其对物种分化速率的影响。
研究结果：我们发现，歧化选择可能促使开阔植被生境中的类群演化出与封闭森林类群截然不同的性状与气候生态位最适值。此外，本研究表明，开阔生境、干燥温暖和/或地中海型气候，与小型硬叶具齿叶片之间的交互作用，提升了山龙眼科的净分化速率。
主要结论：本研究结果显示，特定叶片适应性性状的演化，或许让山龙眼科植物能够适应多样的气候生态位，并在开普植物区与西南澳大利亚植物区等开阔生态系统中实现大规模物种分化。因此，形态与环境的这种匹配关系，或可普遍引发进化辐射。