State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; School of Biological Sciences, Nanjing Normal University, Nanjing 210046, China.
Sci Total Environ. 2020 Nov 1;741:140462. doi: 10.1016/j.scitotenv.2020.140462. Epub 2020 Jun 24.
Community variation (i.e., beta diversity) along geographical gradients is a well-known ecological pattern, but the corresponding variation in beta diversity components (e.g., species turnover and nestedness) and underlying drivers remain poorly understood. Based on two alternative approaches (that is, the beta diversity partitioning proposed by Baselga and the Local Contributions to Beta Diversity (LCBD) partitioning proposed by Legendre), we examined the patterns of beta diversity components of lacustrine benthos, from bacteria to diatoms and chironomids, in the surface sediments along a 100-m water-depth gradient in Lugu Lake. We further quantified the relative importance of spatial, environmental and biotic variables in explaining water-depth patterns in beta diversity. Based on the Baselga's framework, there was a taxonomic dependency for the patterns of beta diversity components with water-depth, showing a significant species turnover pattern for bacteria, while diatoms and chironomids showed significant nestedness. This dependency was also evident in the patterns of community uniqueness with water-depth because based on Legendre's framework, the LCBD decreased with water depth for bacteria whereas increased with depth for diatoms. The total beta diversity and species turnover of bacteria could be explained by the pure effects of spatial, environmental and biotic variables. A total of 26.8% and 23.6% of the nestedness component of diatoms and chironomids was explained by environmental variables, respectively, while species turnover was mostly related to spatial variables. Bacteria total LCBD and species replacement were driven only by environmental variables. For diatoms and chironomids, however, most of the total LCBD and its two components were explained by spatial variables, and biotic variables were most important for the diatom replacement component. Our findings provide insights into the mechanisms responsible for community organizations along water-depth gradients from the perspective of beta diversity components.
沿地理梯度的群落变异（即β多样性）是一种众所周知的生态模式，但β多样性组成部分（如物种周转率和嵌套性）及其潜在驱动因素的相应变化仍知之甚少。基于两种替代方法（即 Baselga 提出的β多样性划分和 Legendre 提出的 Local Contributions to Beta Diversity（LCBD）划分），我们研究了泸沽湖表层沉积物中从细菌到硅藻和摇蚊的湖底生物β多样性组成部分的模式，水深梯度为 100 米。我们进一步量化了空间、环境和生物变量在解释β多样性水深模式方面的相对重要性。根据 Baselga 的框架，β多样性组成部分与水深的模式存在分类依赖性，表明细菌的物种周转率模式显著，而硅藻和摇蚊则表现出显著的嵌套性。这种依赖性在群落独特性与水深的关系中也很明显，因为根据 Legendre 的框架，LCBD 对于细菌随水深而减少，而对于硅藻则随深度增加而增加。细菌的总β多样性和物种周转率可以用空间、环境和生物变量的纯效应来解释。硅藻和摇蚊嵌套成分的 26.8%和 23.6%分别可以用环境变量来解释，而物种周转率主要与空间变量有关。细菌的总 LCBD 和物种替代仅由环境变量驱动。然而，对于硅藻和摇蚊，LCBD 的大部分总组成部分及其两个组成部分主要由空间变量解释，而生物变量对硅藻替代组成部分最为重要。我们的研究结果从β多样性组成部分的角度提供了对水深梯度上群落组织机制的深入了解。
