Table 6_Comparative assessment of Texas horned lizard (Phrynosoma cornutum) gut microbiome diversity and composition throughout transition from captivity to wild.xlsx

Microbiomes play a key role in the health of animal hosts. To improve conservation translocation programs like headstarting, it is necessary to consider how the structure of these programs impact the host-associated microbiome. Bringing animals into captivity introduces novel diets and environments; however, the extent to which these factors contribute to the structure of the host’s gut microbiome remains poorly understood. Additionally, it is unclear if periods of captivity leave a lasting signature on the host-associated gut microbiome, which could impact individual health and fitness in the long-term. In this study, we repeatedly sampled the gut microbiome of a cohort of headstart Texas horned lizards (Phrynosoma cornutum) throughout their transition from captivity to the wild. We also collected samples of extrinsic microbial communities present in their captive and wild diet and environment. Finally, we sampled the gut microbiome of wild resident lizards to serve as a baseline comparison. Using 16S rRNA microbial inventories, we examined differences in microbial community composition and diversity between pre-release headstart, post-release headstart, and resident lizards of the wild population. Additionally, we assessed the contribution of environmental and dietary microbial communities to the assembly of P. cornutum gut microbiomes in captivity and the wild. Our results suggest captive P. cornutum harbor gut microbiomes that are distinct from their wild counterparts. However, within two-months post-release, the headstart gut microbiome restructures to be indistinguishable from the wild resident microbiome. Microbiomes associated with the captive diet and environment are distinct in beta diversity, but not alpha diversity, from those in the wild. Our results provide important insights into host-associated microbiome dynamics associated with transition from captivity to the wild and can be used to inform conservation translocation practices.

微生物组（microbiome）在动物宿主的健康中发挥关键作用。为优化诸如先期育幼放归（headstarting）这类保护迁地项目，亟需厘清此类项目的实施模式如何影响宿主关联微生物组。将动物转入圈养环境会引入全新的日粮与栖息环境，但目前学界对这些因素在多大程度上塑造宿主肠道微生物组结构仍知之甚少。此外，圈养阶段是否会在宿主肠道微生物组中留下持久印记，进而长期影响个体健康与生存适合度，目前仍不明确。
本研究对一批先期育幼放归的德克萨斯角蜥（Phrynosoma cornutum）从圈养到野生环境的过渡过程进行了肠道微生物组的重复采样。同时采集了其圈养日粮、野生日粮以及对应栖息环境中的外源微生物群落样本。此外还采集了野生定居蜥群的肠道微生物组样本，以作为基准对照。
本研究基于16S rRNA微生物组测序数据，对比分析了放归前先期育幼放归个体、放归后先期育幼放归个体以及野生定居蜥群的微生物群落组成与多样性差异。同时评估了环境与日粮中的微生物群落，对圈养及野生状态下德克萨斯角蜥肠道微生物组组装过程的贡献度。
研究结果显示，圈养德克萨斯角蜥的肠道微生物组与野生个体存在显著差异。但在放归后两个月内，先期育幼放归个体的肠道微生物组会发生重构，其组成与野生定居蜥群已无显著差异。
圈养日粮与环境关联的微生物组在β多样性上与野生对应样本存在显著差异，但α多样性无显著区别。
本研究结果为厘清圈养至野生环境过渡过程中的宿主关联微生物组动态变化提供了重要见解，同时可为保护迁地实践提供科学参考。