Data from: Living on a volcano's edge: genetic isolation of an extremophile terrestrial metazoan

Communities of organisms inhabiting extreme terrestrial environments provide a unique opportunity to study evolutionary forces that drive population structure and genetic diversity under the combined challenges posed by multiple geogenic stressors. High abundance of an invasive pantropical earthworm (and the absence of indigenous lumbricid species) in the Furnas geothermal field (Sao Miguel Island, Azores) indicates its remarkable tolerance to high soil temperature, exceptionally high carbon dioxide and low oxygen levels, and elevated metal bioavailability, conditions which are lethal for the majority of terrestrial metazoans. Mitochondrial and nuclear markers were used to analyze the relationship between populations living inside and outside the geothermal field. Results showed that Pontoscolex corethrurus (Annelida, Oligochaeta, Glossoscolecidae) to be a genetically heterogeneous complex within the Sao Miguel landscape and is probably differentiated into cryptic species. The population exposed to the hostile soil conditions within the volcanic caldera possesses the lowest within-population mitochondrial diversity but an unexpectedly high degree of nuclear variability with several loci evidencing positive selection, parameters indicative of a genetically unique population only distantly related to conspecifics living outside the caldera. In conclusion, P. corethrurus inhabiting active volcanic soil is a discrete extremophile population that has evolved by tolerating a mixture of non-anthropogenic chemical and physical stressors.

栖息于极端陆地环境的生物群落，为探究多重地质成因胁迫因子共同作用下驱动种群结构与遗传多样性的进化动力，提供了独特的研究契机。位于亚速尔群岛圣米格尔岛的福尔纳斯地热田，其生境中入侵性泛热带蚯蚓种群丰度极高，且本土正蚓科（Lumbricidae）物种完全缺失，这表明该蚯蚓对极高土壤温度、异常高浓度二氧化碳、低氧水平以及升高的金属生物有效性具备极强耐受性——而此类环境条件对绝大多数陆地后生动物（metazoans）而言均是致命的。本研究采用线粒体分子标记与核分子标记，分析了地热田内外种群的亲缘关系。结果显示，远盲蚓（Pontoscolex corethrurus，环节动物门（Annelida）、寡毛纲（Oligochaeta）、亮盲蚓科（Glossoscolecidae））在圣米格尔岛的分布范围内属于遗传异质性复合体，大概率已分化为隐存物种（cryptic species）。栖息于火山破火山口（volcanic caldera）内恶劣土壤条件的种群，其线粒体种群内多样性最低，但核基因组变异程度却显著偏高，且多个位点呈现正选择（positive selection）信号；这些参数表明，该种群是遗传上独特的类群，与破火山口外的同种个体亲缘关系极为疏远。综上，栖息于活跃火山土壤的远盲蚓是一类独立的极端耐受种群，其通过耐受多种非人为来源的化学与物理胁迫因子而演化形成。