Institute of Ecology, Friedrich Schiller University of Jena, Dornburger Strafe 159, 07749 Jena, Germany.
Ecology. 2013 Feb;94(2):465-77. doi: 10.1890/11-2279.1.
The importance of competition between similar species in driving community assembly is much debated. Recently, phylogenetic patterns in species composition have been investigated to help resolve this question: phylogenetic clustering is taken to imply environmental filtering, and phylogenetic overdispersion to indicate limiting similarity between species. We used experimental plant communities with random species compositions and initially even abundance distributions to examine the development of phylogenetic pattern in species abundance distributions. Where composition was held constant by weeding, abundance distributions became overdispersed through time, but only in communities that contained distantly related clades, some with several species (i.e., a mix of closely and distantly related species). Phylogenetic pattern in composition therefore constrained the development of overdispersed abundance distributions, and this might indicate limiting similarity between close relatives and facilitation/complementarity between distant relatives. Comparing the phylogenetic patterns in these communities with those expected from the monoculture abundances of the constituent species revealed that interspecific competition caused the phylogenetic patterns. Opening experimental communities to colonization by all species in the species pool led to convergence in phylogenetic diversity. At convergence, communities were composed of several distantly related but species-rich clades and had overdispersed abundance distributions. This suggests that limiting similarity processes determine which species dominate a community but not which species occur in a community. Crucially, as our study was carried out in experimental communities, we could rule out local evolutionary or dispersal explanations for the patterns and identify ecological processes as the driving force, underlining the advantages of studying these processes in experimental communities. Our results show that phylogenetic relations between species provide a good guide to understanding community structure and add a new perspective to the evidence that niche complementarity is critical in driving community assembly.
相似物种间竞争在驱动群落组装中的重要性一直存在争议。最近，人们研究了物种组成中的系统发育模式，以帮助解决这个问题：系统发育聚类暗示环境过滤，而系统发育离散度则表明物种之间的限制相似性。我们使用具有随机物种组成和初始均匀丰度分布的实验植物群落，来研究物种丰度分布中系统发育模式的发展。通过除草来保持组成不变，丰度分布随时间变得离散，但仅在包含远缘类群的群落中，这些类群中有几个物种（即，密切和远缘物种的混合）。因此，组成中的系统发育模式限制了离散丰度分布的发展，这可能表明近亲之间存在限制相似性，而远亲之间存在促进/互补作用。将这些群落中的系统发育模式与组成物种的单培养丰度的预期模式进行比较，结果表明种间竞争导致了系统发育模式。向物种库中的所有物种开放实验群落进行殖民化，导致系统发育多样性趋同。在趋同过程中，群落由几个远缘但物种丰富的类群组成，并且丰度分布具有离散性。这表明限制相似性过程决定了哪些物种主导群落，但不能决定哪些物种存在于群落中。至关重要的是，由于我们的研究是在实验群落中进行的，因此我们可以排除模式的本地进化或扩散解释，并将生态过程确定为驱动力，这突显了在实验群落中研究这些过程的优势。我们的研究结果表明，物种之间的系统发育关系为理解群落结构提供了很好的指导，并为生态位互补在驱动群落组装中至关重要的证据提供了新的视角。
