Living on a volcano's edge: genetic isolation of an extremophile terrestrial
metazoan |
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Authors: | L Cunha R Montiel M Novo P Orozco-terWengel A Rodrigues A J Morgan P Kille |
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Institution: | 1.Cardiff School of Biosciences, Cardiff
University, Park Place, Cardiff, UK;2.Centro de Investigação de
Recursos Naturais (CIRN), Universidade dos Açores, Ponta Delgada, Portugal;3.Langebio, CINVESTVAV, Irapuato-León, México;4.Centro de Vulcanologia e
Avaliação de Riscos Geológicos (CVARG), Universidade dos
Açores, Ponta Delgada, Portugal |
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Abstract: | 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. |
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Keywords: | Pontoscolex corethrurus volcanic soils cryptic speciation earthworm population structure geothermal field |
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