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- Landscape genetics of a seagrass species in a tidal mudflat lagoonPublication . Berković, B.; Serrão, Ester; Alberto, FilipeIn this thesis I looked at different components of dispersal in the seagrass Zostera noltii, from the dispersal potential of both sexual and asexual propagules to indirect genetic estimation and landscape genetics analysis. My studies show that the dispersal biology of Z. noltii is very dependent on commonly underestimated asexual dispersal. This asexual LDD is the most parsimonious explanation for the wide distribution of clones in the lagoon and dramatically changes our view of the species’ life history. Furthermore, I propose that the observed lack of association between landscape features and spatial genetic structure is a consequence of this LDD of asexual propagules. The high dispersal capacity of Z. noltii combined with a tidal regime which homogenizes the otherwise complex lagoon habitat, are prevalent over any effects of landscape on gene flow caused by the lagoon complexity as shown by the landscape genetics analyses. Nevertheless, sexual reproduction also affects spatial genetic structure, as the positive kinship between clones within a 3 km range is a signature of restricted seed dispersal.
- Extending the life history of a clonal aquatic plant: dispersal potential of sexual and asexual propagules of Zostera noltiiPublication . Berković, Buga; Cabaço, Susana; Barrio, Juan M.; Santos, Rui; Serrão, Ester; Alberto, F.The dispersal potential of sexual and asexual propagules of Zostera noltii was experimentally quantified in still water and under different currents in microcosm and mesocosm facilities. We estimated sinking rates of seeds and changes over time in shoot buoyancy, shoot viability, fragment breakage, shoot growth rate and spathe release rate of floating fragments. The fast sinking rates of detached Z. noltii seeds suggest a small spatial scale of dispersal insufficient to connect fragmented populations, whereas the traits of floating fragments, particularly shoot buoyancy and shoot survival (>55 d), suggest a potential for long distance dispersal (>2300 km) that could connect distant patches and allow colonization of new areas. We showed that the Z. noltii vegetative and reproductive fragments have the potential to extend the dispersal achieved by detached seeds alone.