Crist Thomas O, Veech Joseph A, Gering Jon C, Summerville Keith S
Department of Zoology, Miami University, Oxford, Ohio 45056, USA.
Am Nat. 2003 Dec;162(6):734-43. doi: 10.1086/378901. Epub 2003 Dec 19.
Species diversity may be additively partitioned within and among samples (alpha and beta diversity) from hierarchically scaled studies to assess the proportion of the total diversity (gamma) found in different habitats, landscapes, or regions. We developed a statistical approach for testing null hypotheses that observed partitions of species richness or diversity indices differed from those expected by chance, and we illustrate these tests using data from a hierarchical study of forest-canopy beetles. Two null hypotheses were implemented using individual- and sample-based randomization tests to generate null distributions for alpha and beta components of diversity at multiple sampling scales. The two tests differed in their null distributions and power to detect statistically significant diversity components. Individual-based randomization was more powerful at all hierarchical levels and was sensitive to departures between observed and null partitions due to intraspecific aggregation of individuals. Sample-based randomization had less power but still may be useful for determining whether different habitats show a higher degree of differentiation in species diversity compared with random samples from the landscape. Null hypothesis tests provide a basis for inferences on partitions of species richness or diversity indices at multiple sampling levels, thereby increasing our understanding of how alpha and beta diversity change across spatial scales.
物种多样性可以在分层尺度研究的样本内部和样本之间进行累加划分（α多样性和β多样性），以评估在不同栖息地、景观或区域中发现的总多样性（γ多样性）的比例。我们开发了一种统计方法，用于检验零假设，即观察到的物种丰富度或多样性指数划分与偶然预期的划分不同，并且我们使用来自森林冠层甲虫分层研究的数据来说明这些检验。使用基于个体和基于样本的随机化检验来实施两个零假设，以在多个采样尺度上为多样性的α和β成分生成零分布。这两种检验在其零分布和检测具有统计学意义的多样性成分的能力方面有所不同。基于个体的随机化在所有分层水平上更具效力，并且对由于个体的种内聚集导致的观察到的划分与零划分之间的差异敏感。基于样本的随机化效力较小，但对于确定与来自景观的随机样本相比，不同栖息地在物种多样性方面是否表现出更高程度的分化可能仍然有用。零假设检验为在多个采样水平上推断物种丰富度或多样性指数的划分提供了基础，从而增进了我们对α和β多样性如何在空间尺度上变化的理解。
