Smithsonian Tropical Research Institute, Balboa, República de Panamá, University of California, Santa Barbara, CA 93106, USA.
Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
Proc Biol Sci. 2020 Apr 8;287(1924):20192367. doi: 10.1098/rspb.2019.2367. Epub 2020 Apr 1.
Microbes are ubiquitous throughout the world's oceans, yet the manner and extent of their influence on the ecology and evolution of large, mobile fauna remains poorly understood. Here, we establish the intestinal microbiome as a hidden, and potentially important, 'functional trait' of tropical herbivorous fishes-a group of large consumers critical to coral reef resilience. Using field observations, we demonstrate that five common Caribbean fish species display marked differences in where they feed and what they feed on. However, in addition to space use and feeding behaviour-two commonly measured functional traits-we find that interspecific trait differences are even more pronounced when considering the herbivore intestinal microbiome. Microbiome composition was highly species specific. Phylogenetic comparison of the dominant microbiome members to all known microbial taxa suggest that microbiomes are comprised of putative environmental generalists, animal-associates and fish specialists (resident symbionts), the latter of which mapped onto host phylogeny. These putative symbionts are most similar to-among all known microbes-those that occupy the intestines of ecologically and evolutionarily related herbivorous fishes in more distant ocean basins. Our findings therefore suggest that the intestinal microbiome may be an important functional trait among these large-bodied consumers.
微生物在世界海洋中无处不在，但它们对大型、移动的动物群的生态和进化的影响方式和程度仍知之甚少。在这里，我们将肠道微生物组确定为热带草食性鱼类的一个隐藏的、潜在重要的“功能特征”，而这些鱼类是对珊瑚礁恢复力至关重要的大型消费者群体。通过实地观察，我们证明了五种常见的加勒比鱼类在觅食地点和食物种类上存在明显差异。然而，除了通常测量的两个功能特征——空间利用和摄食行为，我们还发现，在考虑草食性鱼类的肠道微生物组时，种间特征差异更为明显。微生物组组成在很大程度上具有物种特异性。对主要微生物组成员与所有已知微生物类群的系统发育比较表明，微生物组由潜在的环境广适种、动物伴生物种和鱼类专性种（驻留共生种）组成，后者与宿主系统发育相对应。与所有已知微生物相比，这些假定的共生种与在更远的海洋盆地中与草食性鱼类在生态和进化上相关的鱼类的肠道中存在的微生物最为相似。因此，我们的研究结果表明，肠道微生物组可能是这些大型消费者的一个重要功能特征。
