Berga Mercè, Östman Örjan, Lindström Eva S, Langenheder Silke
Department of Ecology and Genetics, Limnology, Uppsala University, Uppsala, Sweden.
Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala, Sweden.
Environ Microbiol. 2015 Jul;17(7):2275-87. doi: 10.1111/1462-2920.12688. Epub 2015 Jan 27.
Effects of dispersal and the presence of predators on diversity, assembly and functioning of bacterial communities are well studied in isolation. In reality, however, dispersal and trophic interactions act simultaneously and can therefore have combined effects, which are poorly investigated. We performed an experiment with aquatic metacommunities consisting of three environmentally different patches and manipulated dispersal rates among them as well as the presence or absence of the keystone species Daphnia magna. Daphnia magna reduced both local and regional diversity, whereas dispersal increased local diversity but decreased beta-diversity having no net effect on regional diversity. Dispersal modified the assembly mechanisms of bacterial communities by increasing the degree of determinism. Additionally, the combination of the D. magna and dispersal increased the importance of deterministic processes, presumably because predator-tolerant taxa were spread in the metacommunity via dispersal. Moreover, the presence of D. magna affected community composition, increased community respiration rates but did not affect bacterial production or abundance, whereas dispersal slightly increased bacterial production. In conclusion, our study suggests that predation by a keystone species such as D. magna and dispersal additively influence bacterial diversity, assembly processes and ecosystem functioning.
扩散以及捕食者的存在对细菌群落多样性、组装和功能的影响已分别得到充分研究。然而，在现实中，扩散和营养相互作用是同时发生的，因此可能具有综合影响，但对此的研究却很少。我们对由三个环境不同的斑块组成的水生集合群落进行了一项实验，控制了它们之间的扩散速率以及关键物种大型溞的有无。大型溞降低了局部和区域多样性，而扩散增加了局部多样性但降低了β多样性，对区域多样性没有净影响。扩散通过增加确定性程度改变了细菌群落的组装机制。此外，大型溞和扩散的共同作用增加了确定性过程的重要性，可能是因为耐捕食类群通过扩散在集合群落中得以传播。而且，大型溞的存在影响了群落组成，提高了群落呼吸速率，但未影响细菌生产或丰度，而扩散略微增加了细菌生产。总之，我们的研究表明，像大型溞这样的关键物种的捕食作用和扩散对细菌多样性、组装过程和生态系统功能具有累加影响。
