Appalachian Laboratory, University of Maryland Centre for Environmental Science, Frostburg, MD 21532, USA.
Proc Biol Sci. 2013 Aug 7;280(1768):20131201. doi: 10.1098/rspb.2013.1201. Print 2013 Oct 7.
A common approach for analysing geographical variation in biodiversity involves using linear models to determine the rate at which species similarity declines with geographical or environmental distance and comparing this rate among regions, taxa or communities. Implicit in this approach are weakly justified assumptions that the rate of species turnover remains constant along gradients and that this rate can therefore serve as a means to compare ecological systems. We use generalized dissimilarity modelling, a novel method that accommodates variation in rates of species turnover along gradients and between different gradients, to compare environmental and spatial controls on the floras of two regions with contrasting evolutionary and climatic histories: southwest Australia and northern Europe. We find stronger signals of climate history in the northern European flora and demonstrate that variation in rates of species turnover is persistent across regions, taxa and different gradients. Such variation may represent an important but often overlooked component of biodiversity that complicates comparisons of distance-decay relationships and underscores the importance of using methods that accommodate the curvilinear relationships expected when modelling beta diversity. Determining how rates of species turnover vary along and between gradients is relevant to understanding the sensitivity of ecological systems to environmental change.
一种分析生物多样性地理变化的常用方法是使用线性模型来确定物种相似性随地理或环境距离的下降速度，并在区域、分类群或群落之间比较这种速度。这种方法隐含着一些理由不充分的假设，即物种更替率在梯度上保持不变，因此可以作为比较生态系统的一种手段。我们使用广义差异模型，这是一种新方法，可以适应沿梯度和不同梯度的物种周转率变化，来比较具有不同进化和气候历史的两个地区的植物区系的环境和空间控制因素：澳大利亚西南部和北欧。我们发现北欧植物区系中气候历史的信号更强，并证明了物种周转率变化在不同地区、分类群和不同梯度上都是持续存在的。这种变化可能代表了生物多样性的一个重要但经常被忽视的组成部分，这使得距离衰减关系的比较变得复杂，并强调了使用适应于在建模 beta 多样性时预期的曲线关系的方法的重要性。确定物种周转率在梯度上和梯度之间的变化如何，对于理解生态系统对环境变化的敏感性具有重要意义。
