The microbiota of metazoans can be influenced by a variety of factors including diet, environment and genetics. In this study we sampled multiple populations from 2 host species that do not overlap in distribution, in order to test whether their bacterial microbiotas are speciesspecific or more variable. Intestinal swabs were collected from loggerhead turtles originating from Florida, USA, and Queensland, Australia, as well as from flatback turtles from Crab Island, Queensland, and Port Hedland, Western Australia. We then manually extracted bacterial DNA and used 16S rRNA sequencing to explore bacterial microbial community composition and structure. Our investigation showed that the bacterial microbiota of sea turtles is heavily influenced by geography, with loggerhead turtles originating from the USA and Australia harbouring significantly different bacterial microbial populations in terms of composition. Similarly, we also found that flatback turtles from Crab Island had significantly less diverse microbiotas, with a predominance of the bacterial phylum Firmicutes, in comparison to their genetically similar counterparts from Port Hedland. Factors that may explain these observed differences between populations include host genetics, differences in foraging habitat quality and differences in migratory distance (and thus durations of inappetence) between foraging and breeding grounds. The mechanisms by which these factors may influence bacterial microbial composition of sea turtle gastrointestinal tracts warrants further investigation. The results of this study highlight the importance of interpreting microbiota data of wild animals in the context of geography.

中文翻译：

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海龟的肠道细菌微生物群因地理不同的种群而异

后生动物的微生物群会受到多种因素的影响，包括饮食、环境和遗传。在这项研究中，我们从分布上不重叠的 2 个宿主物种中采样了多个种群，以测试它们的细菌微生物群是否具有物种特异性或更可变。肠道拭子采集自来自美国佛罗里达州和澳大利亚昆士兰州的红海龟，以及来自昆士兰州蟹岛和西澳大利亚州黑德兰港的平背龟。然后我们手动提取细菌 DNA 并使用 16S rRNA 测序来探索细菌微生物群落组成和结构。我们的调查表明，海龟的细菌微生物群受地理影响很大，来自美国和澳大利亚的红海龟在组成方面具有显着不同的细菌微生物种群。同样，我们还发现，与来自黑德兰港的基因相似的同类相比，来自蟹岛的平背龟的微生物群多样性明显较少，其中以厚壁菌门为主。可以解释这些观察到的种群之间差异的因素包括宿主遗传学、觅食栖息地质量的差异以及觅食和繁殖地之间迁徙距离（以及食欲不振的持续时间）的差异。这些因素可能影响海龟胃肠道细菌微生物组成的机制值得进一步研究。