Data from: Environmental heterogeneity dynamics drive plant diversity on oceanic islands

Aim: The General Dynamic Model (GDM) links island biogeographical processes to island geological history. A key premise of the GDM implies that environmental factors shaping the ecology and evolution of insular biota follow a hump-shaped trend over the island’s life span and drive dynamics in carrying capacity, species diversity and endemism. An important component of the GDM is environmental heterogeneity (EH), but its effects on insular diversity remain poorly understood. Here, we first quantified EH, tested whether EH follows the expected hump-shaped trend along island ontogeny and evaluated how EH relates to plant diversity. Location: 135 oceanic islands of volcanic origin. Taxon: Vascular plants. Methods: We calculated 20 alternative EH metrics for focusing on topographic and climatic components of EH, and comparing whole-island metrics (e.g., range) and moving-window metrics (e.g., roughness). Using linear mixed-effects models, we evaluated the trends of EH with island age and the EH-plant diversity relationship expected based on the GDM. Results: Our analysis revealed some EH components to be collinear, e.g., elevation and temperature heterogeneity, but also underlined that EH metrics capture different aspects of EH, e.g., climatic gradients vs. climatic complexity. EH generally followed a hump-shaped trend with island age with an early peak in island ontogeny. Among the EH components, climatic heterogeneity had the strongest effect on plant species richness and elevation heterogeneity on endemism. Including EH into previous analytical models to test the GDM improved their predictive power. Main conclusions: The EH metrics compared here captured various attributes of the environment that influence insular plant diversity. In line with the GDM, our results strongly support the hump-shaped relationship between EH and island age, suggesting that islands become highly heterogeneous early in their ontogeny. Finally, the contribution of EH to GDM-based models of species richness and endemism suggests that EH is a main driver of the diversity of oceanic island biotas.研究目的：通用动力学模型（General Dynamic Model，GDM）将岛屿生物地理过程与岛屿地质历史联系起来。GDM的核心前提是，塑造岛屿生物类群生态与演化的环境因子，会随岛屿生命周期呈现驼峰形趋势，并驱动环境容纳量、物种多样性及特有性的动态变化。环境异质性（environmental heterogeneity，EH）是GDM的重要组成部分，但目前其对岛屿生物多样性的影响仍有待深入阐释。本研究首先量化了环境异质性，检验其是否符合岛屿个体发育过程中的预期驼峰形趋势，并评估了环境异质性与植物多样性的关联。 研究区域：135个火山成因的大洋岛屿。 研究类群：维管植物。 研究方法：我们构建了20种备选环境异质性量化指标，聚焦于环境异质性的地形与气候组分，并对比了全岛尺度指标（如范围）与移动窗口尺度指标（如粗糙度）。通过线性混合效应模型，我们评估了环境异质性随岛屿年龄的变化趋势，以及基于GDM预期的环境异质性与植物多样性之间的关联。 研究结果：分析显示部分环境异质性组分存在共线性，例如海拔异质性与温度异质性，但同时也表明不同环境异质性指标捕捉了环境异质性的不同维度，例如气候梯度与气候复杂度。整体而言，环境异质性随岛屿年龄呈现驼峰形趋势，在岛屿个体发育早期达到峰值。在各类环境异质性组分中，气候异质性对植物物种丰富度的影响最为显著，而海拔异质性则对特有性影响最大。将环境异质性纳入此前用于检验GDM的分析模型后，模型的预测能力得到了提升。 主要结论：本研究对比的环境异质性指标，捕捉了影响大洋岛屿植物多样性的各类环境属性。与GDM的预期一致，我们的研究结果强烈支持环境异质性与岛屿年龄之间存在驼峰形关系，表明岛屿在个体发育早期即会呈现高度的环境异质性。最后，环境异质性对基于GDM的物种丰富度与特有性模型的贡献表明，环境异质性是大洋岛屿生物类群多样性的主要驱动因子。