Evolutionary history of the fucus spiralis / fucus guiryi complex - large-scale analysis of the distribution range and genetic structure across the Northern Hemisphere

• Autor(a) principal: Prinz, Amelie Bettina
• 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/10400.1/15512
• topic: Fucus spp; Biogeography; Intertidal; Hybridization; Range shifts; Species

This master thesis addresses a large-scale biogeographical question, the distribution and evolutionary history of a marine species complex with a vast distribution in the northern hemisphere. This complex includes two intertidal brown macroalgae, Fucus spiralis and Fucus guiryi, whose boundaries, degree of isolation and ranges are imperfectly known. The species Fucus guiryi has been recently separated from Fucus spiralis, and several studies have been undertaken to investigate its geographical distribution and identifying the factors determining it, especially in the face of global warming and rising sea surface temperature. The essential ecosystem services that are provided by these canopy-forming macroalgae together with factors that threaten this species, highlight the need for enhanced research. In this study a genetic diversity and differentiation analysis were applied, using microsatellites and mitochondrial DNA for assessing the influence of historical and ongoing processes in explaining species distributions, range limits and gene-pools, which are driven by great climate events such as the last glacial maximum as well as, potentially, historical and ongoing hybridization. In addition to the genetic methods, species distribution models (SDM) were developed to investigate niche differences and assess potential near-future range shifts under two contrasting climate change scenarios. Genetic analyses revealed that the investigated species complex does not consist of the aforementioned species, instead we recognize a third genetic entity currently under F. guiryi: Fucus macroguiryi. Besides the distinct lower vertical position along the shore in comparison to Fucus spiralis and Fucus guiryi, when in sympatry, Fucus macroguiryi shows a clear genetic and morphologically separation to its relatives. Most interesting results regarding species boundaries, ranges, structure and hybridization SDMs showed that the fate of the three described entities are highly different. Fucus spiralis will experience a great increase in suitable habitat for the future within the “worst case” climate scenario, contrastingly to Fucus guiryi, which will potentially have to face extreme reduction in its population sizes in the southern margins and might even face local extinctions. Fucus macroguiryi showed a poleward shift and relict populations in Morocco could as well vanish in the near future.