Assessing connectivity between coastal populations using genetic and morphometric tools

Tese de doutoramento, Biologia (Genética), Universidade de Lisboa, Faculdade de Ciências, 2009A continuing challenge in evolutionary biology is to understand the processes by which populations become genetically distinct. In general, genetic drift and local adaptation are counteracted by the unifying effects of gene flow. In many marine organisms, gene flow is high due to a planktonic life stage that can result in movement over large distances. The combination of high dispersal and few barriers to larval movement presents a challenge for understanding how divergence occurs in marine environments. Although the predominant mechanisms leading to population differentiation are not always clear, several factors may be important either singly or in combination, including limited dispersal ability, local adaptation, oceanographic currents, habitat discontinuities, isolation-by-distance and historic vicariance. Here it is focused the impact of biogeographic barriers, geographical distance and habitat discontinuities on genetic differentiation in marine organisms. The aim of this study was to determine the influence of biogeography, oceanography and ecology on the population structure and morphology of different crustacean and gastropod species with emphasis on their larval development and distribution along a latitudinal gradient. It is predicted that the duration of larval development influences the dispersal capability and therefore the level of genetic differentiation. These results provide evidence that dispersal play an important role in determining the genetic structure of a species, but the biogeographic history and physical and environmental factors have also a considered influence on it. Thus, adaptive plasticity could also be an explanation for variability. This study also contributes to future studies on morphometric investigations. The results suggest that in studies of morphological population differentiation on crustaceans, the right chela is more suitable to use in homochelous crabs. If the crab is heterochelous, the male major chela and the female right chela should be used. The results also indicate that geometric morphometrics yields stronger evidence of morphological differences among forms, suggesting that this method may be more suitable for analysis of body shape.Resumo alargado em português disponível no documentoFundação para a Ciência e a Tecnologia (FCT), through a PhD grant co-financed by Science and Innovation Operational Programme 2010 (POCI 2010) and European Social Fund (FSE), and attributed to Maria Inês Cristóvão Lourenço da Silva (SFRH/BD/14325/2003). GeneDif Project (Genetic and morphological differentiation in estuarine organisms with contrasting dispersal modes along a geographical gradient) funded by FCT (POCTI/BSE/45672/2002). Transmap Project (Transboundary networks of marine protected areas for integrated conservation and sustainable development: biophysical, socio-economic and governance assessment in East Africa) funded by the European Union (INCO-CT2004-510862