Department of Zoology and Oxford Centre for Integrative Systems Biology, University of Oxford, Oxford OX1 3PS, UK.
Curr Biol. 2012 Oct 9;22(19):1845-50. doi: 10.1016/j.cub.2012.08.005. Epub 2012 Sep 6.
Microbial cells secrete numerous enzymes, scavenging molecules, and signals that can promote the growth and survival of other cells around them [1-4]. This observation is consistent with the evolution of cooperation within species [5], and there is now an increasing emphasis on the importance of cooperation between different microbial species [4, 6]. We lack, however, a systematic test of the importance of mutually positive interactions between different species, which is vital for assessing the commonness and importance of cooperative evolution in natural communities. Here, we study the extent of mutually positive interaction among bacterial strains isolated from a common aquatic environment. Using data collected from two independent experiments evaluating community productivity across diversity gradients, we show that (1) in pairwise species combinations, the great majority of interactions are net negative and (2) there is no evidence that strong higher-order positive effects arise when more than two species are mixed together. Our data do not exclude the possibility of positive effects in one direction where one species gains at the expense of another, i.e., predator-prey-like interactions. However, these do not constitute cooperation and our analysis suggests that the typical result of adaptation to other microbial species will be competitive, rather than cooperative, phenotypes.
微生物细胞分泌大量的酶、清除分子和信号分子，这些物质可以促进周围其他细胞的生长和存活[1-4]。这一观察结果与物种内合作的进化是一致的[5]，现在越来越强调不同微生物物种之间合作的重要性[4,6]。然而，我们缺乏对不同物种之间相互积极相互作用的重要性进行系统测试，而这对于评估合作进化在自然群落中的普遍性和重要性至关重要。在这里，我们研究了从常见水生环境中分离出的细菌菌株之间相互积极相互作用的程度。利用从两个独立实验中收集的评估多样性梯度上群落生产力的数据，我们表明：（1）在种间两两组合中，绝大多数相互作用是净负面的；（2）当混合两种以上物种时，没有证据表明会出现强烈的高阶正效应。我们的数据并不排除一种情况下的单向正效应的可能性，即一个物种以牺牲另一个物种为代价而获益，即类似于捕食者-猎物的相互作用。然而，这些并不构成合作，我们的分析表明，适应其他微生物物种的典型结果将是竞争而非合作的表型。
