Population genetics of the Marbled rockcod Notothenia rossii in the Scotia Arc, Antarctica
The Southern Ocean surrounding the Antarctic continent harbours a highly distinct and specialized ichthyofauna with 107 of the species belonging to the perciform suborder Notothenioidei, which represents one of the rare cases of an adaptive radiation in the marine realm. For this unique fish group,...
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| Format: | Thesis |
| Language: | English |
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2015
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| Online Access: | https://oceanrep.geomar.de/id/eprint/40386/ https://oceanrep.geomar.de/id/eprint/40386/1/MSc.%202015%20M%C3%BCller,F.M.pdf |
| Summary: | The Southern Ocean surrounding the Antarctic continent harbours a highly distinct and specialized ichthyofauna with 107 of the species belonging to the perciform suborder Notothenioidei, which represents one of the rare cases of an adaptive radiation in the marine realm. For this unique fish group, knowledge about population connectivity and genetic structure is important for disentangling the factors that regulate gene flow among populations and influence speciation processes. Furthermore, understanding population identity and demographic history is a prerequisite for decision-making in management and conservation. In this regard, the Marbled rockcod Notothenia rossii is of special interest due to its distribution in an environment affected by rapid climate change and having been heavily targeted by fisheries in the 1970s, leading to a collapse of stocks in the Scotia Arc area. In this thesis, I have examined the population genetic structure and diversity of N rossii from the Atlantic sector of the Southern Ocean by using two different types of genetic markers. Overall, 93 specimens from Elephant Island, South Georgia Island and South Orkney Islands were analyzed with 7 cross-amplified microsatellite loci and one mitochondrial DNA marker ( cytochrome b ). Various measures of genetic differentiation and several clustering approaches were utilized to verify the results of an earlier study indicating the absence of genetic structuring between groups of individuals from different sampling locations and to identify genetic clusters of individuals. My results confam the lack of genetic differentiation for populations of N rossii in the Scotia Arc and provide tentative support for the hypothesis of subtle differences in the connectivity patterns among the investigated locations. In addition, coalescent-based methods allow insights into the demographic history of this species and hint at the occurrence of a large-scale expansion. Overall, the findings presented in this thesis point out that equilibrating levels of gene ... |
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