PhD student: Mariana Padron, Thesis director : Katell Guizien, Thesis adjunc director : Marco Abbiati ( Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (BiGeA), Universita di Bologna, Italy)
Thesis defended the 24th of november 2015
Connectivity is expected to strongly influence the dynamics and persistence of marine populations. Studying the development and maintenance of connectivity patterns among marine populations is, thus, essential for spatial planning and the proper design and management of Marine Protected Areas (MPAs). However, understanding the complex processes driving marine population connectivity requires the use of tools that integrate bio-physical models with information regarding the demographic and genetic linkages resulting from the larval exchange among populations. Therefore, the aim of this PhD dissertation is to evaluate the patterns of genetic connectivity among gorgonian populations at a regional scale, and disentangle the processes that shape the observed connectivity by using model simulations accounting for hydrological, demographic and genetic connectivity. The first chapter presents a spatially explicit metapopulation model that, using stochastic connectivity matrices, assesses the effect of demography on allele frequencies in a marine metapopulation of sessile benthic species. The model is then used to evaluate the effect of demographic traits and connectivity structure on the genetic diversity of a marine metapopulation. The second chapter examines the patterns of genetic connectivity of two common and widely distributed gorgonian species at a regional scale: Paramuricea clavata in the Ligurian Sea, and Eunicella singularis in the Gulf of Lions. Both species exhibit strong patterns of genetic structure at a regional scale, although the dispersal capacity of each species does not seem limited (>100 m). The third chapter discerns among the potential processes shaping the realized connectivity of E. singularis in the Gulf of Lions by applying the model presented in Chapter 1, and comparing the modeled patterns of genetic structure to the results obtained from empirical genetic data in Chapter 2. Modeled and empirical results show similar patterns of genetic structure among populations of E. singularis in the region. Genetic and demographic differentiation among populations is demonstrated to result from the spatial structure of dispersal alone. The ability to evaluate the expected development of genetic structure among populations under different demographic and hydrological scenarios using the seascape model presented in Chapter 1 provides a useful tool with relevance for marine spatial planning and the persistence of marine populations.
Evaluation of conservation efficiency for gorgonian species at a regional scale based on an existing Marine Protected Area network in the Ligurian sea and modeling scenarios accounting for hydrodynamical connectivity.
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