Data from: The phylogeny and biogeography of Hakea (Proteaceae) reveals the role of biome shifts in a continental plant radiation

The frequency of evolutionary biome shifts during diversification has important implications for our ability to explain geographic patterns of plant diversity. Recent studies present several examples of biome shifts, but whether frequencies of biome shifts closely reflect geographic proximity or environmental similarity of biomes remains poorly known. We explore this question by using phylogenomic methods to estimate the phylogeny of Hakea, a diverse Australian genus occupying a wide range of biomes. Model-based estimation of ancestral regions indicates that Hakea began diversifying in the Mediterranean biome of southern Australia in the Middle Eocene – Early Oligocene, and dispersed repeatedly into other biomes across the continent. We infer around 47 shifts between biomes. Frequencies of shifts between pairs of biomes are usually similar to those expected from their geographic connectedness or climatic similarity, but in some cases are substantially higher or lower than expected, perhaps reflecting how readily key physiological traits can be modified to adapt lineages to new environments. The history of frequent biome-shifting is reflected in the structure of present-day assemblages, which tend to be more phylogenetically diverse than null-model expectations. The case of Hakea demonstrates that the radiation of large plant clades across wide geographic areas need not be constrained by dispersal limitation or conserved adaptations to particular environments.

物种分化过程中演化生物群区（biome）的转移频率，对于解释植物多样性的地理分布格局具有重要理论意义。现有研究已报道多起生物群区转移案例，但这类转移频率是否紧密对应生物群区的地理邻近性与环境相似性，目前仍缺乏明确认知。本研究以占据澳大利亚多样生境的大型属类——哈克木属（Hakea）为研究对象，采用系统基因组学方法推断其系统发育关系，以此探讨上述科学问题。基于模型的祖先区域重建结果显示，哈克木属起源于澳大利亚南部的地中海型生物群区，其类群分化始于中始新世至早渐新世，并多次扩散至澳洲大陆其他生物群区。本研究共推断出约47次生物群区转移事件。成对生物群区间的转移频率，通常与其地理连通性或气候相似性的预期值相符，但部分案例中的转移频率显著高于或低于预期，这或许反映了关键生理性状的改造难易程度，决定了演化支能否顺利适应新环境。频繁发生的生物群区转移历史，也体现在当前植物群落的结构特征中：此类群落的系统发育多样性往往高于零模型（null model）的预期水平。哈克木属的研究案例表明，大型植物演化支在广阔地理范围内的辐射演化，未必会受到扩散限制或对特定环境的保守适应性所束缚。