Department of Biological and Environmental Sciences, P.O. Box 65, FIN-00014, University of Helsinki, Finland.
Ecology. 2010 Feb;91(2):508-17. doi: 10.1890/09-0392.1.
Recent meta-analyses have shown that beta diversity through space is jointly driven by species traits, geographical gradients, and ecosystem properties. Spatial variation is, however, only one aspect of beta diversity. The other component is variation in species assemblages through time, that is, temporal turnover. We examined the decrease of assemblage similarity in time in aquatic ecosystems in relation to several ecological, physical, and geographical factors using an extensive data set derived from the literature. The data set was first divided into intra-annual and interannual studies depending on the temporal extent of the studies. Sampling duration was one the most significant variables affecting the degree of temporal turnover, and we found that turnover was faster in studies with shorter temporal extent. Our results further suggested that the rate of temporal turnover increased with increasing ecosystem size, thus contradicting the general species-time-area relationship. Temporal turnover also varied among the ecosystem types: lake assemblages showed faster turnover than stream or marine assemblages in the interannual data set. We found that temporal turnover exhibited large-scale geographical variation, as there was a latitudinal gradient in turnover. Turnover was faster in the tropics in the intra-annual data set, but the pattern was reversed in the interannual data set, where turnover was faster at high latitudes. Finally, we found that the degree of temporal turnover was related to organism characteristics, as larger organisms with active mobility showed slower temporal turnover than smaller organisms. Our results suggest that the degree of species turnover in time is jointly driven by several ecological, physical, and geographical factors in aquatic ecosystems and that the turnover is not uniform across taxonomic groups. Our findings have important consequences for understanding how different biotic assemblages track temporal changes in the environment and how resilient assemblages are toward such changes.
最近的荟萃分析表明，通过空间的β多样性是由物种特征、地理梯度和生态系统特性共同驱动的。然而，空间变化只是β多样性的一个方面。另一个组成部分是物种组合随时间的变化，即时间周转率。我们使用从文献中得出的广泛数据集，研究了水生生态系统中物种组合相似性随时间的减少与几个生态、物理和地理因素的关系。该数据集首先根据研究的时间范围分为年内和年际研究。采样持续时间是影响时间周转率程度的最重要变量之一，我们发现，在时间范围较短的研究中，周转率更快。我们的结果还表明，随着生态系统规模的增加，时间周转率的速率增加，从而与一般的物种-时间-面积关系相矛盾。时间周转率也因生态系统类型而异：在年际数据集，湖泊组合的周转率快于溪流或海洋组合。我们发现，时间周转率表现出大尺度的地理变化，因为在周转率中存在纬度梯度。在年内数据集，周转率在热带较快，但在年际数据集，这种模式发生了逆转，在高纬度，周转率较快。最后，我们发现，时间周转率的程度与生物体特征有关，因为具有主动移动能力的较大生物体比较小生物体的时间周转率较慢。我们的研究结果表明，水生生态系统中物种随时间的周转率是由几个生态、物理和地理因素共同驱动的，并且周转率在分类群之间并不均匀。我们的研究结果对理解不同生物组合如何跟踪环境的时间变化以及组合对这些变化的弹性具有重要意义。
