Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, 08028 Barcelona, Spain.
Institute for Research on Biodiversity (IRBio), University of Barcelona, 08028 Barcelona, Spain.
FEMS Microbiol Ecol. 2018 Feb 1;94(2). doi: 10.1093/femsec/fix186.
Compositional variation of the gut microbiota across host allopatric populations can reflect both adaptation and stochasticity since the time of separation. Major factors shaping this variation include the host phylogeographic and demographic history, the microbiota inheritance, environmental inputs and dispersal of bacteria. Here we explored the impact of these factors in driving gut community diversity in seven allopatric populations of the omnivorous lizard Podarcis lilfordi from the Menorcan coastal islets, all descending from an ancestral mainland population. Using 16S rRNA Illumina sequencing, we showed that 'islet' and 'age' (time since islet separation from mainland) were the only significant variables in microbial community clustering, suggesting a partial islet-restricted diversification following these lizards phylogeography. Despite a significant variation, islets/populations were characterized by a remarkably low bacterial uniqueness (2.4% of total OTUs) and a minor differential enrichment of taxa, indicating a negligible impact of local inputs and important host common constraints. Overall, the extant pattern of similarity/dissimilarity among islets is compatible with partial retention of the ancestral mainland microbial pool, with differences among islets potentially explained by a differential loss of bacteria following population fragmentation and bottlenecks (i.e. ecological drift). While more quantitative data are needed to validate this hypothesis, this study unveils the importance of considering both neutral and niche-driven processes in driving contemporary patterns of gut metacommunity diversity.
肠道微生物群落的组成在宿主异地种群之间的变化可以反映出适应和随机性，因为它们在分离时就已经存在了。影响这种变化的主要因素包括宿主的系统地理学和种群历史、微生物群落的遗传、环境输入以及细菌的扩散。在这里，我们研究了这些因素在驱动来自梅诺卡沿海岛屿的杂食性蜥蜴 Podarcis lilfordi 的七个异地种群的肠道群落多样性方面的作用，这些蜥蜴都来自于一个祖先的大陆种群。通过使用 16S rRNA Illumina 测序，我们表明“岛屿”和“年龄”（从岛屿与大陆分离以来的时间）是微生物群落聚类的唯一显著变量，这表明这些蜥蜴的系统地理学导致了部分岛屿限制的多样化。尽管存在显著的变化，但岛屿/种群的细菌独特性（总 OTU 的 2.4%）和分类群的差异丰度非常低，这表明局部输入和重要的宿主共同限制的影响可以忽略不计。总的来说，岛屿之间的相似性/相异性的现存模式与对祖先大陆微生物库的部分保留是一致的，岛屿之间的差异可能是由于种群破碎化和瓶颈（即生态漂移）导致的细菌的差异丢失所解释的。虽然需要更多的定量数据来验证这一假设，但本研究揭示了在驱动当代肠道后生群落多样性模式时，考虑中性和生态位驱动过程的重要性。
