Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec City, QC, Canada.
Department of Ecology, Environment and Evolution, School of Life Science, La Trobe University, Bundoora, Vic., Australia.
Mol Ecol. 2019 Aug;28(15):3612-3626. doi: 10.1111/mec.15184. Epub 2019 Aug 11.
The world's richest freshwater fish community thrives in gradients of contrasting environments in Amazonia, ranging from ion-poor acidic black waters, to ion-rich circumneutral white waters. These hydrochemical gradients structure Amazonian fish assemblages via ecological speciation events. Fish bacterial communities contain an important genetic heritage essential for their hosts' survival and are also involved in adaptive divergence via niche adaptation processes, but the extent to which they evolve in response to hydrochemical gradients in Amazonia is unknown. Here we investigated bacterial communities (gut and skin mucus) of two ecologically and phylogenetically divergent host species (Mesonauta festivus and Serrasalmus rhombeus) distributed throughout these hydrochemical gradients. The goal was to characterize intra- and interspecific Amazonian fish microbiome variations across multiple scales. Using a 16S metabarcoding approach, we investigated the microbiota of 43 wild M. festivus, 32 S. rhombeus and seven water samples, collected at seven sampling sites encompassing both water colours. Taxonomical structures of bacterial communities from both host species were significantly correlated to the environmental continua of magnesium, sodium, dissolved organic carbon, calcium, dissolved O , pH, potassium, hardness and chloride. Analysis of discriminating features in community structures across multiple scales demonstrated intra- and interspecific structural parallelisms in the response to the hydrochemical gradients. Together, these parallelisms suggest the action of selection on bacterial community structures along Amazonian hydrochemical gradients. Functional approaches along with reciprocal transplant experiments will provide further insights on the potential contribution of Amazonian fish microbiomes in host adaptation and ecological speciation events.
世界上最丰富的淡水鱼类群落栖息在亚马逊地区环境对比度很大的梯度中，从离子贫乏的酸性黑水到离子丰富的近中性白水。这些水化学梯度通过生态物种形成事件构建了亚马逊鱼类群落。鱼类细菌群落包含宿主生存所必需的重要遗传遗产，并且还通过生态位适应过程参与适应性分化，但它们在多大程度上响应亚马逊的水化学梯度而进化尚不清楚。在这里，我们调查了分布在这些水化学梯度中的两种生态和系统发育上有差异的宿主物种（Mesonauta festivus 和 Serrasalmus rhombeus）的细菌群落（肠道和皮肤粘液）。目标是描述亚马逊鱼类微生物组在多个尺度上的种内和种间变异。使用 16S 代谢组学方法，我们调查了 43 个野生 M. festivus、32 个 S. rhombeus 和 7 个水样的微生物群，这些样本是在涵盖两种水色的 7 个采样点采集的。来自两种宿主物种的细菌群落的分类结构与镁、钠、溶解有机碳、钙、溶解氧、pH 值、钾、硬度和氯的环境连续体显著相关。对跨多个尺度的群落结构中区分特征的分析表明，在对水化学梯度的响应中存在种内和种间结构的平行现象。这些平行现象表明，选择作用于亚马逊水化学梯度沿线的细菌群落结构。功能方法和相互移植实验将进一步深入了解亚马逊鱼类微生物组在宿主适应和生态物种形成事件中的潜在贡献。
