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Please use this identifier to cite or link to this item: http://hdl.handle.net/10451/1596

Título: The evolution of Squalius alburnoides (Teleostei: cyprinidae) populations in the northern Iberian Peninsula : a molecular genetics and morphological approach into the past and present dynamics of an hybrid complex
Autor: Cunha, Carina João Alves da, 1975-
Orientador: Coelho, Maria Manuela, 1954-
Doadrio, Ignacio
Palavras-chave: Hibridação
Complexo S. alburnoides
Marcadores moleculares
Dinâmica populacional
Especiação alopoliplóide
Teses de doutoramento
Issue Date: 2009
Resumo: The main objective of this thesis was to assess the northern populations' genetic structure of the Iberian hybrid complex Squalius alburnoides in order to unveil its evolutionary history, population structure and dynamics. The mtDNA molecular phylogenetic analyses suggest that S. alburnoides has at least five lineages of independent origin (Sado, Alagón Tributary Douro, Tagus Mondego, Guadiana-Guadalquivir and Southwest). Those hybridization events took place over a long period of time and can be traced back to the Pliocene. Geographic variation in the reproductive mechanisms of S. alburnoides may explain the differences observed in the composition of biotypes. Different genetic signatures in Mondego and Douro basins reflect different populations' history. Low allelic diversity in the A genome of Mondego and the sharing of mtDNA lineages with Tagus populations reflect colonization from Tagus basin. The marked population structure, high frequency of private alleles and the diversity of biotypes observed in Douro indicate that it is not condemned in the long term, as suspected. The results also support the existence of a glacial refugium in the Rabaçal River. The geometric morphometrics results showed significant variation in body shape between S. carolitertii and S. alburnoides and between tetraploids and the other biotypes that may reduce resource competition. The adaptation to different trophic niches through modification of trophic morphology, body shapes, and feeding behaviour seem to result from ploidy augmentation and genomic constitution and may account for the formation and maintenance of this complex. Based on the flow cytometry measurements, microsatellite loci and experimental crosses, two symmetric allotetraploid populations were described, that resumed normal meiosis after undergoing intermediate processes of non-sexual reproduction to give rise to a new sexually reproducing polyploid species. Prezygotic and postzygotic mechanisms are responsible for the reproductive isolation from other biotypes of the complex. The future of the southern and northern populations depends on their genetic legacy and population dynamics, possibly introducing fresh genes that will eventually lead to new speciation processes.
Descrição: Tese de doutoramento em Biologia (Biologia Evolutiva), apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2009
URI: http://sibul.reitoria.ul.pt/F/?func=item-global&doc_library=ULB01&type=03&doc_number=000551228
Appears in Collections:FC - Teses de Doutoramento

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