Josefson Alf B
Department of Bioscience, Aarhus University, Roskilde, Denmark.
PLoS One. 2016 Dec 22;11(12):e0168908. doi: 10.1371/journal.pone.0168908. eCollection 2016.
The relative importance of environment and dispersal related processes for community assembly has attracted great interest over recent decades, but few empirical studies from the marine/estuarine realm have examined the possible effects of these two types of factors in the same system. Importance of these processes was investigated in a hypothetical metacommunity of benthic invertebrates in 16 micro-tidal estuaries connected to the same open sea area. The estuaries differed in size and connectivity to the open sea and represented a salinity gradient across the estuaries. The Elements of Metacommunity Structure (EMS) approach on estuary scale was complemented with a mechanistic variance partitioning approach on sample scale to disentangle effects of factors affecting assembly of three trait groups of species with different dispersivity. A quasi-Clementsian pattern was observed for all three traits, a likely response to some latent gradient. The primary axis in the pattern was most strongly related to gradients in estuary salinity and estuary entrance width and correlation with richness indicated nestedness only in the matrix of the most dispersive trait group. In the variance partitioning approach measures of turnover and nestedness between paired samples each from different estuaries were related to environmental distance in different gradients. Distance between estuaries was unimportant suggesting importance of factors characterizing the estuaries. While the high dispersive species mainly were sorted in the salinity gradient, apparently according to their tolerance ranges towards salinity, the two less dispersive traits were additionally affected by estuary entrance width and possibly also area. The results exemplify a mechanism of community assembly in the marine realm where the niche factor salinity in conjunction with differential dispersal structure invertebrates in a metacommunity of connected estuaries, and support the idea that dispersive species are more controlled by the environment than less dispersive species.
近几十年来，环境和扩散相关过程对群落构建的相对重要性引起了极大关注，但海洋/河口领域的实证研究很少在同一系统中考察这两类因素的可能影响。我们在一个与同一公海区域相连的16个微潮河口的底栖无脊椎动物假设集合群落中，研究了这些过程的重要性。这些河口在大小和与公海的连通性方面存在差异，代表了整个河口的盐度梯度。在河口尺度上采用集合群落结构要素（EMS）方法，并在样本尺度上辅以机制方差分解方法，以厘清影响具有不同扩散性的三个物种性状组组装的因素的影响。对于所有三个性状都观察到了一种类似克莱门茨的模式，这可能是对某种潜在梯度的响应。该模式的主轴与河口盐度和河口入口宽度的梯度最密切相关，与丰富度的相关性表明仅在最具扩散性的性状组矩阵中存在嵌套性。在方差分解方法中，来自不同河口的配对样本之间的周转率和嵌套性测量值与不同梯度中的环境距离相关。河口之间的距离并不重要，这表明表征河口的因素很重要。虽然高扩散性物种主要在盐度梯度中进行分选，显然是根据它们对盐度的耐受范围，但另外两个扩散性较低的性状还受到河口入口宽度以及可能还有面积的影响。研究结果例证了海洋领域群落构建的一种机制，即在相连河口的集合群落中，生态位因素盐度与不同的扩散性共同塑造了无脊椎动物的结构，并支持了扩散性物种比扩散性较低的物种更受环境控制这一观点。
