Ord Terry J, Emblen Jack, Hagman Mattias, Shofner Ryan, Unruh Sara
Evolution and Ecology Research Centre and the School of Biological Earth and Environmental Sciences University of New South Wales Kensington NSW Australia.
Ecol Evol. 2017 Jun 20;7(15):5845-5860. doi: 10.1002/ece3.3126. eCollection 2017 Aug.
Theory predicts deterministic and stochastic factors will contribute to community assembly in different ways: Environmental filters should regulate those species that establish in a particular area resulting in the ecological requirements of species being the primary driver of species distributions, while chance and dispersal limitation should dictate the likelihood of species reaching certain areas with the ecology of species being largely neutral. These factors are specifically relevant for understanding how the area and isolation of different habitats or islands interact to affect community composition. Our review of the literature found few experimental studies have examined the interactive effect of habitat area and isolation on community assembly, and the results of those experiments have been mixed. We manipulated the area and isolation of rock "islands" created de novo in a grassland matrix to experimentally test how deterministic and stochastic factors shape colonizing animal communities. Over 64 weeks, the experiment revealed the primacy of deterministic factors in community assembly, with habitat islands of the same size exhibiting remarkable consistency in community composition and diversity, irrespective of isolation. Nevertheless, tangible differences still existed in abundance inequality among taxa: Large, near islands had consistently higher numbers of common taxa compared to all other island types. Dispersal limitation is often assumed to be negligible at small spatial scales, but our data shows this not to be the case. Furthermore, the dispersal limitation of a subset of species has potentially complex flow-on effects for dictating the type of deterministic factors affecting other colonizing species.
理论预测，确定性因素和随机因素将以不同方式影响群落构建：环境过滤应调节那些在特定区域定居的物种，从而使物种的生态需求成为物种分布的主要驱动因素，而偶然性和扩散限制则应决定物种到达某些区域的可能性，此时物种生态在很大程度上是中性的。这些因素对于理解不同栖息地或岛屿的面积和隔离如何相互作用以影响群落组成尤为重要。我们对文献的综述发现，很少有实验研究考察栖息地面积和隔离对群落构建的交互作用，而且这些实验的结果参差不齐。我们对在草地基质中全新创建的岩石“岛屿”的面积和隔离进行了操控，以通过实验测试确定性因素和随机因素如何塑造定居动物群落。在64周的时间里，该实验揭示了确定性因素在群落构建中的首要地位，相同大小的栖息地岛屿在群落组成和多样性方面表现出显著的一致性，与隔离情况无关。然而，不同分类单元之间在丰度不平等方面仍然存在明显差异：与所有其他岛屿类型相比，大型近岛的常见分类单元数量一直更高。通常认为扩散限制在小空间尺度上可以忽略不计，但我们的数据表明并非如此。此外，一部分物种的扩散限制对于决定影响其他定居物种的确定性因素类型可能具有潜在的复杂连锁效应。
