Garcia Justine R, Gerardo Nicole M
Gerardo Lab, Department of Biology, O. Wayne Rollins Research Center, Emory University, Atlanta, GA USA.
Front Microbiol. 2014 Sep 26;5:510. doi: 10.3389/fmicb.2014.00510. eCollection 2014.
Microbial associations are integral to all eukaryotes. Mutualism, the interaction of two species for the benefit of both, is an important aspect of microbial associations, with evidence that multicellular organisms in particular benefit from microbes. However, the microbe's perspective has largely been ignored, and it is unknown whether most microbial symbionts benefit from their associations with hosts. It has been presumed that microbial symbionts receive host-derived nutrients or a competition-free environment with reduced predation, but there have been few empirical tests, or even critical assessments, of these assumptions. We evaluate these hypotheses based on available evidence, which indicate reduced competition and predation are not universal benefits for symbionts. Some symbionts do receive nutrients from their host, but this has not always been linked to a corresponding increase in symbiont fitness. We recommend experiments to test symbiont fitness using current experimental systems of symbiosis and detail considerations for other systems. Incorporating symbiont fitness into symbiosis research will provide insight into the evolution of mutualistic interactions and cooperation in general.
微生物关联对于所有真核生物来说都是不可或缺的。互利共生，即两个物种相互作用并使双方都受益，是微生物关联的一个重要方面，有证据表明多细胞生物尤其能从微生物中获益。然而，微生物的视角在很大程度上被忽视了，而且大多数微生物共生体是否从与宿主的关联中受益尚不清楚。据推测，微生物共生体从宿主那里获得源自宿主的营养物质，或者处于一个捕食减少的无竞争环境中，但这些假设很少有实证检验，甚至缺乏批判性评估。我们基于现有证据对这些假设进行评估，这些证据表明竞争减少和捕食减少并非共生体普遍能获得的益处。一些共生体确实从宿主那里获取营养物质，但这并不总是与共生体适应性的相应增加相关联。我们建议利用当前的共生实验系统来测试共生体适应性的实验，并详细说明对其他系统的考虑因素。将共生体适应性纳入共生研究将为互利相互作用和一般合作的进化提供见解。
