Biodiversity metrics often integrate data on the presence and abundance of multiple species. Yet our understanding of covariation between changes to the numbers of individuals, the evenness of species relative abundances, and the total number of species remains limited. Using individual-based rarefaction curves, we show how expected positive relationships among changes in abundance, evenness and richness arise, and how they can break down. We then examined interdependencies between changes in abundance, evenness and richness in more than 1100 assemblages sampled either through time or across space. As predicted, richness changes were greatest when abundance and evenness changed in the same direction, and countervailing changes in abundance and evenness acted to constrain the magnitude of changes in species richness. Site-to-site differences in abundance, evenness, and richness were often decoupled, and pairwise relationships between these components across assemblages were weak. In contrast, changes in species richness and relative abundance were strongly correlated for assemblages varying through time. Temporal changes in local biodiversity showed greater inertia and stronger relationships between the component changes when compared to site-to-site variation. Overall, local variation in assemblage diversity was rarely due to repeated passive samples from an approximately static species abundance distribution. Instead, changing species relative abundances often dominated local variation in diversity. Moreover, how changing relative abundances combined with changes to total abundance frequently determined the magnitude of richness changes. Embracing the interdependencies between changing abundance, evenness and richness can provide new information to better understand biodiversity change in the Anthropocene.

中文翻译：

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当地生物多样性变化反映了不断变化的丰度、均匀度和丰富度之间的相互作用

生物多样性指标通常会整合有关多种物种存在和丰度的数据。然而，我们对个体数量变化、物种相对丰度的均匀性和物种总数之间的协变的理解仍然有限。使用基于个体的稀疏曲线，我们展示了丰度、均匀度和丰富度变化之间预期的正相关关系是如何产生的，以及它们是如何分解的。然后，我们检查了通过时间或空间采样的 1100 多个组合中丰度、均匀度和丰富度变化之间的相互依赖性。正如预测的那样，当丰度和均匀度沿同一方向变化时，丰富度变化最大，丰度和均匀度的抵消变化限制了物种丰富度的变化幅度。丰度、均匀度和丰富度的站点间差异通常是分离的，并且这些组件之间的成对关系在组合中很弱。相比之下，物种丰富度和相对丰度的变化与随时间变化的组合密切相关。与地点到地点的变化相比，当地生物多样性的时间变化显示出更大的惯性和成分变化之间更强的关系。总体而言，组合多样性的局部变化很少是由于来自近似静态物种丰度分布的重复被动样本。相反，不断变化的物种相对丰度通常主导着多样性的局部变化。此外，相对丰度的变化如何与总丰度的变化相结合，通常决定了丰富度变化的幅度。