The relationship between animals and their gut flora is simultaneously one of the most common and most complex symbioses on Earth. Despite its ubiquity, our understanding of this invisible but often critical relationship is still in its infancy. We employed adult Neotropical butterflies as a study system to ask three questions: First, how does gut microbial community composition vary across host individuals, species and dietary guilds? Second, how do gut microbiota compare to food microbial communities? Finally, are gut flora functionally adapted to the chemical makeup of host foods? To answer these questions we captured nearly 300 Costa Rican butterflies representing over 50 species, six families, and two feeding guilds: frugivores and nectivores. We characterized bacteria and fungi in guts, wild fruits, and wild nectars via amplicon sequencing and assessed the catabolic abilities of the gut microbiota via culture‐based assays. Gut communities were distinct from food communities, suggesting that the gut environment acts as a filter on potential colonists. Nevertheless, gut flora varied widely among individuals and species. On average, a pair of butterflies shared 21% of their bacterial species and 6% of their fungi. Host species explained 25–30% of variation in microbial communities while host diet explained 4%, suggesting that non‐dietary aspects of host biology play a large role in structuring the butterfly gut flora. Much of the variation between species correlated with host phylogeny. Host diet was related to gut microbial function: compared to frugivores, nectivores’ gut flora exhibited increased catabolism of sugars and sugar alcohols and decreased catabolism of amino acids, carboxylic acids, and dicarboxylic acids. Since fermented juice contains more amino acids and less sugar than nectar, it appears that host diet filters the gut flora by favoring microbes that digest compounds abundant in foods. By quantifying the degree to which gut communities vary among host individuals, species and dietary guilds and evaluating how gut microbial composition and catabolic potential are related to host diet, this study highlights the linkages between structure and function in one of the most complex and ubiquitous symbioses in the animal kingdom.

中文翻译：

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新热带蝴蝶的细菌和真菌肠道菌群的结构和功能

动物及其肠道菌群之间的关系同时也是地球上最常见，最复杂的共生体之一。尽管这种关系无处不在，但我们对这种无形但往往是关键性关系的理解仍处于起步阶段。我们采用成年新热带蝴蝶作为研究系统来提出三个问题：首先，肠道微生物群落组成在寄主个体，物种和饮食行会之间如何变化？第二，肠道菌群与食物微生物群落相比如何？最后，肠道菌群是否在功能上适合宿主食品的化学成分？为了回答这些问题，我们捕获了将近300只哥斯达黎加的蝴蝶，它们代表50多个物种，六个科和两个食肉行会：食肉动物和食肉动物。我们对肠道和野果中的细菌和真菌进行了鉴定，和野生花蜜通过扩增子测序，并通过基于培养的分析评估了肠道菌群的分解代谢能力。肠道菌群不同于食物菌群，这表明肠道环境对潜在的殖民者起到了过滤作用。然而，肠道菌群在个体和物种之间差异很大。平均而言，一对蝴蝶共有21％的细菌和6％的真菌。寄主物种解释了25-30％的微生物群落变异，而寄主饮食解释了4％，这表明寄主生物学的非饮食方面在构建蝴蝶肠道菌群中起着重要作用。物种之间的许多变异都与宿主的系统发育有关。宿主饮食与肠道微生物功能有关：与节食动物相比，食肉动物的肠道菌群显示出糖和糖醇的分解代谢增加，而氨基酸，羧酸和二羧酸的分解代谢下降。由于发酵汁比花蜜含有更多的氨基酸和更少的糖，因此宿主饮食似乎通过偏爱消化食物中丰富化合物的微生物来过滤肠道菌群。通过量化肠道菌群在宿主个体，物种和饮食行会之间的差异程度，并评估肠道微生物组成和分解代谢潜能与宿主饮食之间的关系，该研究突出了最复杂和普遍存在的共生体之一的结构与功能之间的联系。在动物界。宿主饮食似乎通过偏爱消化食物中丰富化合物的微生物来过滤肠道菌群。通过量化肠道菌群在宿主个体，物种和饮食行会之间的差异程度，并评估肠道微生物组成和分解代谢潜能与宿主饮食之间的关系，该研究突出了最复杂和普遍存在的共生体之一的结构与功能之间的联系。在动物界。宿主饮食似乎通过偏爱消化食物中丰富化合物的微生物来过滤肠道菌群。通过量化肠道菌群在宿主个体，物种和饮食行会之间的差异程度，并评估肠道微生物组成和分解代谢潜能与宿主饮食之间的关系，该研究突出了最复杂和普遍存在的共生体之一的结构与功能之间的联系。在动物界。