Data from: Diet and phylogeny shape the gut microbiota of Antarctic seals: a comparison of wild and captive animals

The gut microbiota of mammals underpins the metabolic capacity and health of the host. Our understanding of what influences the composition of this community has been limited primarily to evidence from captive and terrestrial mammals. Therefore, the gut microbiota of southern elephant seals, Mirounga leonina, and leopard seals, Hydrurga leptonyx, inhabiting Antarctica were compared with captive leopard seals. Each seal exhibited a gut microbiota dominated by four phyla: Firmicutes (41.5 ± 4.0%), Fusobacteria (25.6 ± 3.9%), Proteobacteria (17.0 ± 3.2%) and Bacteroidetes (14.1 ± 1.7%). Species, age, sex and captivity were strong drivers of the composition of the gut microbiota, which can be attributed to differences in diet, gut length and physiology and social interactions. Differences in particular prey items consumed by seal species could contribute to the observed differences in the gut microbiota. The longer gut of the southern elephant seal provides a habitat reduced in available oxygen and more suitable to members of the phyla Bacteroidetes compared with other hosts. Among wild seals, 16 ‘core’ bacterial community members were present in the gut of at least 50% of individuals. As identified between southern elephant seal mother–pup pairs, ‘core’ members are passed on via vertical transmission from a young age and persist through to adulthood. Our study suggests that these hosts have co-evolved with their gut microbiota and core members may provide some benefit to the host, such as developing the immune system. Further evidence of their strong evolutionary history is provided with the presence of 18 shared ‘core’ members in the gut microbiota of related seals living in the Arctic. The influence of diet and other factors, particularly in captivity, influences the composition of the community considerably. This study suggests that the gut microbiota has co-evolved with wild mammals as is evident in the shared presence of ‘core’ members.

哺乳动物的肠道微生物群（gut microbiota）是宿主代谢能力与健康状态的核心支撑。当前学界对该菌群组成影响因素的认知，主要局限于圈养与陆生哺乳动物的相关研究证据。因此，本研究对栖息于南极洲的南象海豹（Mirounga leonina）、豹海豹（Hydrurga leptonyx）的肠道微生物群，与圈养豹海豹的肠道微生物群进行了对比分析。所有受试海豹的肠道微生物群均由四大菌门主导：厚壁菌门（Firmicutes）占比41.5±4.0%、梭杆菌门（Fusobacteria）占比25.6±3.9%、变形菌门（Proteobacteria）占比17.0±3.2%，以及拟杆菌门（Bacteroidetes）占比14.1±1.7%。物种、年龄、性别以及圈养状态，均为肠道微生物群组成的关键驱动因子，这一现象可归因于饮食、肠道长度与生理特征，以及社会互动的差异。海豹不同物种所摄食的特定猎物种类差异，或可导致观测到的菌群组成差异。南象海豹更长的肠道形成了可利用氧含量更低的栖息环境，相较于其他宿主，更适合拟杆菌门菌群定植。在野生海豹中，至少50%的个体肠道内均存在16种“核心”细菌类群。正如南象海豹母婴对所观测到的结果，这类“核心”类群可从幼年阶段通过垂直传播获得，并持续存活至宿主成年阶段。本研究表明，这些宿主与其肠道微生物群已发生协同进化，核心类群或可为宿主带来诸多益处，例如助力免疫系统发育。栖息于北极的近缘海豹肠道微生物群中，同样存在18种共享的“核心”类群，这进一步佐证了二者间紧密的进化关联。饮食及其他因素（尤其是圈养状态）对菌群组成具有显著影响。本研究证实，野生哺乳动物与其肠道微生物群已发生协同进化，这一点可从“核心”类群的共享分布中得到印证。