A microbial view on secondary contact between two Alpine butterflies

This is the R code with the input data (all.xlsx and as a tab separated text file all.txt) for the analyses presented in A microbial view on secondary contact between two Alpine butterflies published in BMC Ecology & Evolution and authored by Pelin Taş, Arnaud Mouly, Kay Lucek Abstract Background Widespread sympatry between sibling species can be limited if they are ecologically too close, potentially leading to the formation of narrow zones of secondary contact. While the ecological niche is commonly estimated using abiotic factors, the potential differentiation in gut microbial communities as a proxy for biotic niche differentiation is less well studied. We address this gap in research, focusing on two Alpine butterfly species of the genus Erebia that form a stable and very narrow contact zone. Results Using a metabarcoding approach to sequence the adult gut microbial communities of our two focal species as well as capturing the microbial diversity found on three nectar plant species, we found that the microbial community i) significantly differed between species but not between sexes, that ii) the abundance of the heritable endosymbiont Wolbachia differed between species, where its high abundance resulted in the detection of fewer other microbial taxa, and that iii) microbes found on flowers largely but not completely overlapped with the ones found in the butterfly hosts, suggesting that intestinal environmental filtering occurs only to some degree. Conclusions Consistent with biotic niche differentiation, we uncovered species specific differences in the gut microbial communities, further highlighting the complex interactions between host biology and environmental factors in shaping the gut microbiota. The observed microbial differences could reflect local adaptation to different resources or microhabitats. Overall, our study highlights the utility of gut microbial metabarcoding to study ecological niche differentiation, also during secondary contact.本文件包含用于该论文分析的R代码与输入数据（all.xlsx以及制表符分隔文本文件all.txt）。该论文题为《两种高山蝴蝶次生接触的微生物学视角》（A microbial view on secondary contact between two Alpine butterflies），发表于《BMC生态学与进化》（BMC Ecology & Evolution），作者为Pelin Taş、Arnaud Mouly与Kay Lucek。 摘要 研究背景 若姊妹种间生态位过于接近，其广泛同域分布可能受限，进而可能形成狭窄的次生接触带。当前生态位评估通常基于非生物因子，而以肠道微生物群落差异作为生物生态位分化替代指标的相关研究则相对匮乏。本研究针对这一研究空白，聚焦于眼蝶属（Erebia）的两种高山蝴蝶，二者形成了稳定且极窄的接触带。 研究结果 本研究采用宏条形码（metabarcoding）测序技术，对两种靶标物种成虫的肠道微生物群落进行测序，并同时采集了三种蜜源植物表面的微生物多样性数据。研究发现：其一，微生物群落结构在物种间存在显著差异，但在性别间无显著差异；其二，可遗传胞内共生菌沃尔巴克氏体（Wolbachia）的丰度在物种间存在差异，其高丰度会导致其他微生物类群的检出量减少；其三，花表面的微生物与蝴蝶宿主体内的微生物大部分存在重叠，但并非完全一致，这表明肠道环境过滤仅在一定程度上存在。 研究结论 本研究结果与生物生态位分化假说一致，我们发现了两种蝴蝶肠道微生物群落的物种特异性差异，进一步凸显了宿主生物学特性与环境因子在塑造肠道微生物群过程中的复杂相互作用。观测到的微生物差异可能反映了宿主对不同资源或微生境的局部适应。总体而言，本研究证实了肠道微生物宏条形码测序技术在次生接触带生态位分化研究中的应用价值。