The evolution of the size of the geographical range as a key factor in the generation of biodiversity

Why some species have wide geographical distributions while others are apparently restricted to very small areas is a major question in biogeography, ecology and evolutionary biology, with deep implications in the more applied field of conservation biology. Invasive species are nothing more than species that in a short time, and generally through human intervention, have enormously expanded their geographical ranges, sometimes from a very reduced area. Similarly, understanding why some species are able to expand their distribution and occupy geographical areas under different environmental conditions, while others seem unable to move from their location, could be of great help to predict, and eventually counteract, the effects of global climatic change. Despite a large amount of work dedicated to documenting patterns of range size distributions and modelling species ranges, there are few tested hypotheses on how these inequalities originate and evolve. In this project we test several hypotheses on the origin of the differences in the size of the geographical range among groups of closely related species. For that purpose we will use phylogenetically independent lineages of water beetles of at least three families (Dytiscidae, Hydraenidae, Elmidae). Within each of the lineages there are species with very restricted distributions (local endemics, many of them Iberian) and widespread species, in some cases with continental-wide ranges. We will use two different approaches to test these hypotheses: first, molecular phylogenies and phylogeographies of the selected species groups (i.e. we will go beyond the species boundary to the population level), to test hypotheses concerning the relative age, phylogenetic position and geographical origin of the species; and second, a proteomic analyses using two-dimensional electrophoresis of different sister species pairs, one with restricted and the other with widespread distribution, to try to detect possible differences in the global expression of some protein families in specimens living in different environmental conditions.

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