Giant kelp forests of the Falkland Islands - a metapopulation structured by past historical colonization events and by present habitat continuity and oceanographic transportation

• Autor(a) principal: Couraud, Logan Baptiste
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/15362
• topic: Macrocystis pyrifera; Conectividade; Estrutura genética; Filogeografia; LGM

The genetic structure of Macrocystis pyrifera around the Falkland Islands and the Magallean region was determined. In fact, genetic discontinuities related to biogeographic breaks and the role of predictors such as habitat continuity, dispersal, oceanographic currents, and bathymetry were assessed to understand the metapopulation’s structure around the Falklands. In total, 9 microsatellites and one mitochondrial marker were used to genotyped 433 individuals from 22 different populations. Nuclear DNA and Mitochondrial DNA analysis were carried out to comprehend the effects of historical and contemporary effects on species distribution and range shifts. At a large scale, the analysis shows that Macrocystis pyrifera is subdivided into four main genetic clusters, one in the Magallean region, two in the Falkland Islands, and one in South Africa. Furthermore, populations in the Magallean region have displayed a low genetic diversity that can be linked to recent colonization events while around the Falklands a higher genetic diversity have been found that may reflect historical events. The role played by the Falkland Islands as a refugia for this species is well supported by the phylogeographic structure. Genetic analysis revealed that the distribution around the Falklands has been shaped by contemporary and historical events. Multiple genetic breaks have been observed and are concordant with biogeographic and oceanographic breaks. The present genetic structure can be best explained by transportation through ocean currents and habitat continuity for stepping-stone migration rather than by geographical distance. Kelps are under increasing anthropogenic pressure and environmental changes and unlike most other marine species they can be easily monitored. Thus, further studies need to be carried out to highlight more biogeographic and phylogeographic breaks at a global scale to understand the ecological and evolutionary processes that shape the distribution of kelps. In consequence, it will provide more information for management and conservation policies to be taken.