Constraining null models with environmental gradients: a new method for evaluating the effects of environmental factors and geometric constraints on geographic diversity patterns
Constraining null models with environmental gradients: a new method for evaluating the effects of environmental factors and geometric constraints on geographic diversity patterns
复制标题
DOI：
10.1111/j.1600-0587.2012.07384.x
复制
发表时间：
2012-12
期刊：
影响因子：
5.9
通讯作者：
Xiangping Wang;Jingyun Fang
中科院分区：
文献类型：
--
作者：
Xiangping Wang;Jingyun Fang
气候和地理限制对地理多样性格局的相对影响长期以来一直存在争议。我们开发了一种新的方法来评估几何约束在形成海拔丰富度模式的作用。研究表明，中国西南部四座高山的植物物种丰富度受地理约束和环境梯度的共同影响。与以往的研究结果相反，我们的研究结果表明：1）小范围和大范围物种丰富度在很大程度上受相同的环境梯度控制，而不同的主要是几何约束的影响。2)几何约束（除了环境梯度）解释物种丰富度的贡献是更大的物种丰富度在低海拔比在中海拔达到峰值时，这表明几何约束可能是非常重要的丰富度峰值远离中间域。3)将物种丰富度直接与环境因素联系起来（生物多样性研究中最广泛使用的方法）可能会误导几何约束可能影响丰富度格局的情况，因为这种方法可能会高估环境因素的影响，无法区分几何约束的混杂效应。相反，环境因素的影响可以用小范围物种的基本梯度来评估。4)单纯的几何约束模型不能完全评估几何约束的效果，而基于范围的环境梯度约束模型可以更好地评估几何约束的效果。5)如果我们的研究结果的一般性支持其他类群在其他梯度，那么许多以前的研究气候和地理多样性格局的几何约束的影响可能需要重新访问。
The relative effects of climate and geometric constraints on geographic diversity patterns have long been controversial. We developed a new method to assess the role of geometric constraints in shaping altitudinal richness patterns. We showed how plant species richness on four mountains in southwest China are shaped by geometric constraints and environmental gradients together. Contrary to previous studies, our results suggested that: 1) small- and large-ranged species richness were largely controlled by the same environmental gradients, and differed mainly in the effect of geometric constraints. 2) The contribution of geometric constraints (in addition to environmental gradients) to explaining species richness was greater when species richness peaked at low altitudes than at mid-altitudes, suggesting that geometric constraints may be very important when richness peaks are far away from mid-domains. 3) Relating species richness directly to environmental factors (the most widely used method in biodiversity studies) may be misleading when geometric constraints may be affecting the richness pattern, because this method may overestimate the effect of environmental factors by failing to distinguish the confounding effect of geometric constraints. Instead, the effect of environmental factors can be evaluated with an underlying gradient derived from small-ranged species. 4) The geometric constraints effect cannot be fully evaluated by pure geometric constraints models, and is better evaluated with range-based models constrained with environmental gradients. 5) If the generality of our findings is supported for other taxa on other gradients, then many previous studies on the effects of climate and of geometric constraints on geographic diversity patterns may need to be re-visited.