Department of Ecology and Genetics/Limnology, Uppsala University, Uppsala, Sweden.
ISME J. 2011 Jul;5(7):1086-94. doi: 10.1038/ismej.2010.207. Epub 2011 Jan 27.
Many studies have shown that species sorting, that is, the selection by local environmental conditions is important for the composition and assembly of bacterial communities. On the other hand, there are other studies that could show that bacterial communities are neutrally assembled. In this study, we implemented a microcosm experiment with the aim to determine, at the same time, the importance of species sorting and neutral processes for bacterial community assembly during the colonisation of new, that is, sterile, habitats, by atmospheric bacteria. For this we used outdoor microcosms, which contained sterile medium from three different rock pools representing different environmental conditions, which were seeded by rainwater bacteria. We found some evidence for neutral assembly processes, as almost every 4th taxon growing in the microcosms was also detectable in the rainwater sample irrespective of the medium. Most of these taxa belonged to widespread families with opportunistic growth strategies, such as the Pseudomonadaceae and Comamonadaceae, indicating that neutrally assembled taxa may primarily be generalists. On the other hand, we also found evidence for species sorting, as one out of three media selected a differently composed bacterial community. Species sorting effects were relatively weak and established themselves via differences in relative abundance of generalists among the different media, as well as media-specific occurrences of a few specific taxa. In summary, our results suggest that neutral and species sorting processes interact during the assembly of bacterial communities and that their importance may differ depending on how many generalists and specialists are present in a community.
许多研究表明，物种分选，即由局部环境条件选择，对细菌群落的组成和组装非常重要。另一方面，也有其他研究表明细菌群落是中性组装的。在这项研究中，我们进行了一个微宇宙实验，目的是同时确定物种分选和中性过程对大气细菌定植新的、即无菌生境时细菌群落组装的重要性。为此，我们使用了户外微宇宙，其中包含来自三个不同岩石池的无菌培养基，这些岩石池代表不同的环境条件，并用雨水细菌进行了接种。我们发现了一些中性组装过程的证据，因为在微宇宙中生长的几乎每 4 个分类群在雨水样本中都可以检测到，而与培养基无关。这些分类群大多属于具有机会生长策略的广泛家族，如假单胞菌科和贪噬菌科，这表明中性组装的分类群可能主要是广域种。另一方面，我们也发现了物种分选的证据，因为三种培养基中的一种选择了组成不同的细菌群落。物种分选的影响相对较弱，通过不同培养基中广域种的相对丰度差异以及特定培养基中少数特定分类群的存在而建立起来。总之，我们的结果表明，中性和物种分选过程在细菌群落的组装过程中相互作用，它们的重要性可能取决于群落中存在多少广域种和特化种。
