Data and code for "Assembly of functional diversity in an oceanic island flora"

Oceanic island floras are well-known for their morphological peculiarities and exhibit striking examples of trait evolution. These morphological shifts are commonly attributed to insularity and are thought to be shaped by the biogeographical processes and evolutionary histories of oceanic islands. However, the mechanisms through which biogeography and evolution have shaped the distribution and diversity of plant functional traits remain unclear. Here, we describe the functional trait space of the native flora of an oceanic island (Tenerife, Canary Islands, Spain) using extensive field and laboratory measurements, and relate it to global trade-offs in ecological strategies. We find that the island trait space exhibits a remarkable functional richness but that most plants are concentrated around a functional hotspot dominated by shrubs with a conservative life-history strategy. By dividing the island flora into species groups associated with distinct biogeographical distributions and diversification histories, our results also suggest that colonisation via long-distance dispersal and the interplay between inter-island dispersal and archipelago-level speciation processes drive functional divergence and trait space expansion. Contrary to our expectations, speciation via cladogenesis has led to functional convergence, and therefore only contributes marginally to functional diversity by densely packing trait space around shrubs. By combining biogeography, ecology, and evolution our approach opens new avenues for trait-based insights into how dispersal, speciation, and persistence shape the assembly of entire native island floras.

海洋岛屿植物区系（oceanic island floras）以其独特的形态学特征而闻名，同时展现出性状演化（trait evolution）的典型范例。这类形态转变通常被归因于岛屿孤立性（insularity），且被认为受海洋岛屿的生物地理过程与演化历史所塑造。然而，生物地理学与演化过程如何塑造植物功能性状（plant functional traits）的分布与多样性，其背后的机制仍未明晰。本研究通过大规模野外与实验室测量，描述了一座海洋岛屿——西班牙加那利群岛特内里费岛——本土植物区系的功能性状空间（functional trait space），并将其与生态策略的全球权衡相关联。我们发现，该岛屿的功能性状空间展现出极高的功能丰富度（functional richness），但绝大多数植物集中在以保守型生活史策略（conservative life-history strategy）灌木为主导的功能热点（functional hotspot）区域。通过将岛屿本土植物区系划分为具有不同生物地理分布与分化历史（diversification histories）的物种类群，我们的研究结果还表明，经由长距离扩散（long-distance dispersal）的定殖事件，以及岛间扩散（inter-island dispersal）与群岛尺度物种形成（archipelago-level speciation）过程之间的相互作用，推动了功能分化（functional divergence）与性状空间扩张（trait space expansion）。与我们的预期相悖的是，通过分支物种形成（cladogenesis）产生的新类群引发了功能趋同（functional convergence），因此仅通过在灌木类群周围密集填充性状空间，对功能多样性的贡献微乎其微。本研究将生物地理学、生态学与演化生物学相结合，为基于性状的研究开辟了新路径，助力理解扩散、物种形成与种群存续如何塑造整个岛屿本土植物区系的群落构建过程。