Biogeografía de los parásitos sanguíneos en un hospedador aviar modelo con diversas estrategias migratoriasla curruca capirotada sylvia atricapilla

Abstract

The negative effects that parasites have on their hosts’ fitness make of parasitism one of the main evolutive agents. The knowledge of which are the factors that determine the spatiotemporal distribution of parasites impacts is hence critical if we are to anticipate the threat posed by emergent diseases in a context of global change. This PhD Thesis used the blackcap Sylvia atricapilla (Aves: Sylviidae) and its haemosporidian parasites (genera Plasmodium, Haemoproteus y Leucocytozoon; Apicomplexa) as a model system to test how several sources of environmental variation determine the differences on parasite impacts. First we identified which variables in an Iberian context were the main determinants of parasite diversity, finding out that although climatic variables (mainly temperature) were the most relevant ones, including orographic variables into the analyses increased their significance. Then we used this information to predict the current and future distribution of the areas under a strong parasitic pressure in the Iberian Peninsula, forecasting a future reshuffling of the current host-parasite relationships mosaic. We also performed a reconstruction of how different strategies of seasonal transmission (summer transmission, extended summer transmission and year-round transmission) have evolved through the evolutionary history of these parasites, discovering that, although year-round transmission has appeared multiple independent times and it is an ecologically successful strategy, it is not as successful as seasonal transmission in the long run. Finally, by examining the parasitic communities of the blackcaps inhabiting the archipelagos of the Canay Islands and Madeira, we found out that host-parasite relationships are compromised in insular environments, and that insular syndromes (low richness, host switching and host generalism) develop among parasites even before the development of full isolation.