Department of Food and Environmental Sciences/Microbiology and Biotechnology, University of Helsinki, P.O. Box 56, Helsinki 00014, Finland
Department of Biosciences/Ecology and Evolutionary biology, University of Helsinki, P.O. Box 65, Helsinki 00014, Finland.
Proc Biol Sci. 2017 Oct 11;284(1864). doi: 10.1098/rspb.2017.0415.
The theory of species coexistence is a key concept in ecology that has received much attention. The role of rapid evolution for determining species coexistence is still poorly understood although evolutionary change on ecological time-scales has the potential to change almost any ecological process. The influence of evolution on coexistence can be especially pronounced in microbial communities where organisms often have large population sizes and short generation times. Previous work on coexistence has assumed that traits involved in resource use and species interactions are constant or change very slowly in terms of ecological time-scales. However, recent work suggests that these traits can evolve rapidly. Nevertheless, the importance of rapid evolution to coexistence has not been tested experimentally. Here, we show how rapid evolution alters the frequency of two bacterial competitors over time when grown together with specialist consumers (bacteriophages), a generalist consumer (protozoan) and all in combination. We find that consumers facilitate coexistence in a manner consistent with classic ecological theory. However, through disentangling the relative contributions of ecology (changes in consumer abundance) and evolution (changes in traits mediating species interactions) on the frequency of the two competitors over time, we find differences between the consumer types and combinations. Overall, our results indicate that the influence of evolution on species coexistence strongly depends on the traits and species interactions considered.
物种共存理论是生态学中的一个关键概念，受到了广泛关注。尽管在生态时间尺度上的进化变化有可能改变几乎任何生态过程，但快速进化在决定物种共存中的作用仍未得到很好的理解。进化对共存的影响在微生物群落中尤为明显，因为这些生物通常具有较大的种群数量和较短的世代时间。以前关于共存的研究假设，与资源利用和物种相互作用相关的特征是不变的，或者在生态时间尺度上变化非常缓慢。然而，最近的研究表明，这些特征可以快速进化。尽管如此，快速进化对共存的重要性尚未通过实验进行测试。在这里，我们展示了当两种细菌竞争者与专门的消费者（噬菌体）、一般消费者（原生动物）一起生长，以及所有这些消费者组合在一起时，快速进化如何随时间改变两种竞争者的频率。我们发现，消费者以与经典生态学理论一致的方式促进了共存。然而，通过区分消费者丰度变化（生态变化）和物种相互作用中介特征变化（进化变化）对两种竞争者随时间的频率的相对贡献，我们发现了不同消费者类型和组合之间的差异。总体而言，我们的研究结果表明，进化对物种共存的影响强烈取决于所考虑的特征和物种相互作用。
