We tested the hypothesis that the ubiquity of marine meiofaunal nematodes and their indiscriminate passive dispersal create assemblages that are less limited by its environment; whereas the relatively smaller population sizes of macrofauna, associated with their ability to track environmental conditions before settlement, renders their distribution more environmentally-restricted. We compared the empirical distribution of macrofauna and nematode species with that of communities simulated under different assumptions of selection (e.g. environmental filtering) and non-selection (e.g. dispersal limitation) processes. Selection processes were the prime driver of both meio- and macrofauna assemblages, with rare species strongly contributing to this component. The total number of species explained by non-selection processes was 27% higher in nematodes than in macrofauna. Our results underline the importance of a species-level approach to determine the contribution of selection and non-selection assembly processes. Moreover, they highlight the important yet overlooked role of dispersal and stochastic processes in determining species dynamics.

我们检验了以下假设：海洋的淡紫色线虫的普遍存在及其不加区别的被动扩散产生的集合受到环境的限制较少。而大型动物的种群规模相对较小，与其在定居前跟踪环境状况的能力有关，使得其分布受到环境的限制更大。我们将大型动物和线虫物种的经验分布与在选择（例如环境过滤）和非选择（例如分散限制）过程的不同假设下模拟的群落的经验分布进行了比较。选择过程是小型动物和大型动物组合的主要驱动力，稀有物种对此构成了重要贡献。线虫中非选择过程所解释的物种总数比大型动物区系高27％。我们的结果强调了物种水平方法对确定选择和非选择装配过程的贡献的重要性。此外，它们强调了分散和随机过程在确定物种动态中的重要但被忽视的作用。