Functional trait space and the latitudinal diversity gradient
Functional trait space and the latitudinal diversity gradient
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DOI：
10.1073/pnas.1317722111
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发表时间：
2014-09-23
影响因子：
11.1
通讯作者：
Enquist, Brian J.
中科院分区：
文献类型：
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作者：
Lamanna, Christine;Blonder, Benjamin;Enquist, Brian J.
造成物种丰富度纬度梯度的过程仍然难以捉摸。生物多样性梯度起源的生态学理论，如竞争排斥、中性动力学和环境过滤，预测功能多样性在阿尔法（当地组合）、贝塔（组合之间）和伽马（区域池）尺度上应如何变化。我们测试这些预测，通过量化构建的功能性状代表主轴植物策略变化（比叶面积，株高，种子质量）在树木组合跨越温带和热带新世界的超体积。α尺度性状体积随绝对纬度的增加而减小，且往往低于抽样期望值，这与环境过滤理论相一致。在温带，β尺度重叠随地理距离衰减最快，这也与环境过滤理论相一致。相反，伽马尺度的特质空间与绝对纬度呈驼峰形关系，与任何理论都不一致。此外，整体温带性状超体积大于整体热带超体积，表明温带允许更广泛的性状组合或生态位包装在热带地区更强。尽管数据存在局限性，但我们的分析表明，多个过程塑造了树木的性状多样性，这反映出任何一种理论都没有一致的支持。
The processes causing the latitudinal gradient in species richness remain elusive. Ecological theories for the origin of biodiversity gradients, such as competitive exclusion, neutral dynamics, and environmental filtering, make predictions for how functional diversity should vary at the alpha (within local assemblages), beta (among assemblages), and gamma (regional pool) scales. We test these predictions by quantifying hypervolumes constructed from functional traits representing major axes of plant strategy variation (specific leaf area, plant height, and seed mass) in tree assemblages spanning the temperate and tropical New World. Alpha-scale trait volume decreases with absolute latitude and is often lower than sampling expectation, consistent with environmental filtering theory. Beta-scale overlap decays with geographic distance fastest in the temperate zone, again consistent with environmental filtering theory. In contrast, gamma-scale trait space shows a hump-shaped relationship with absolute latitude, consistent with no theory. Furthermore, the overall temperate trait hypervolume was larger than the overall tropical hypervolume, indicating that the temperate zone permits a wider range of trait combinations or that niche packing is stronger in the tropical zone. Although there are limitations in the data, our analyses suggest that multiple processes have shaped trait diversity in trees, reflecting no consistent support for any one theory.