1] Department of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen 18D, Uppsala, Sweden [2] Centre d'Études Nordiques, UMI Takuvik, Départment de biologie-IBIS, Université Laval, Pavillon Charles-Eugène-Marchand, 1030, avenue de la Médecine, Québec (Québec), Canada.
Department of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen 18D, Uppsala, Sweden.
ISME J. 2014 Dec;8(12):2423-30. doi: 10.1038/ismej.2014.89. Epub 2014 Jun 6.
There is now clear evidence that microorganisms present biogeographic patterns, yet the processes that create and maintain them are still not well understood. In particular, the contribution of dispersal and its exact impact on local community composition is still unclear. For example, dispersing cells may not thrive in recipient environments, but may still remain part of the local species pool. Here, we experimentally tested if marine bacteria can be retrieved from freshwater communities (pelagic and sediment) and the atmosphere by exposing bacteria from three lakes, that differ in their proximity to the Norwegian Sea, to marine conditions. We found that the percentage of freshwater taxa decreased with increasing salinities, whereas marine taxa increased along the same gradient. Our results further showed that this increase was stronger for lake and sediment compared with air communities. Further, significant increases in the average niche breadth of taxa were found for all sources, and in particular lake water and sediment communities, at higher salinities. Our results therefore suggests that marine taxa can readily grow from freshwater sources, but that the response was likely driven by the growth of habitat generalists that are typically found in marine systems. Finally, there was a greater proportion of marine taxa found in communities originating from the lake closest to the Norwegian Sea. In summary, this study shows that the interplay between bacterial dispersal limitation and dispersal from internal and external sources may have an important role for community recovery in response to environmental change.
现在有明确的证据表明，微生物具有生物地理分布模式，但创造和维持这些模式的过程仍未得到很好的理解。特别是，扩散的贡献及其对当地群落组成的确切影响仍不清楚。例如，扩散的细胞可能在受体环境中不能茁壮成长，但仍可能成为当地物种库的一部分。在这里，我们通过将来自三个湖泊的细菌暴露于海洋条件下，从淡水群落（浮游生物和沉积物）和大气中实验性地测试了海洋细菌是否可以被回收。我们发现，随着盐度的增加，淡水分类群的百分比减少，而海洋分类群则沿着相同的梯度增加。我们的结果进一步表明，与空气群落相比，湖泊和沉积物的这种增加更为强烈。此外，所有来源的分类群的平均生态位宽度都有显著增加，特别是在高盐度下的湖水和沉积物群落。因此，我们的结果表明，海洋分类群可以从淡水来源中轻易生长，但这种反应可能是由通常在海洋系统中发现的栖息地广食性生物的生长所驱动的。最后，在源自最接近挪威海的湖泊的群落中发现了更多的海洋分类群。总之，这项研究表明，细菌扩散限制和内部及外部来源扩散之间的相互作用可能对群落对环境变化的恢复具有重要作用。
