Biogeography of the Baetic ranges (SE Spain): A historical approach using cluster and parsimony analyses of endemic dolomitophytes

The Baetic ranges are one of the major hot-spots of biodiversity in the Mediterranean basin. The prominent Baetic plant richness is based mostly on the variety of ecological gradients, including the geological substrates such as dolomites. Dolomitic outcrops are not uncommon in the area, and they produce genuine edaphic islands inducing a peculiar flora and vegetation with high endemicity levels. Indeed, the habitats from these outcrops have been included in the Habitats Directive by the EU. This paper deals with the biogeographical relations between the dolomitophilous flora of the Baetic ranges. The presence/absence of those species was recorded in each of the Baetic ranges and the most interesting relations were revealed by means of two complementary strategies: Cluster Analysis and PAE. Using the current biogeographical classification of Rivas-Martinez to describe the results, the ranges of the Rondean Sector appear separated from the rest of the Baetic chorological province, since they comprise the most distinct flora. This division could be explained by the fact that this sector was separated from the Iberian Peninsula during the Messinian age (7.2-5.3 Ma) and, simultaneously, connected to Africa. The rest of the ranges belong to one of the following two groups: (1) the Malacitan-Almijarensean Sector and the western sub-Baetic territories; (2) the eastern territories of the sub-Baetic Sector. The ranges of the Guadician-Bacensean and Alpujarrean-Gadorensean Sectors behave as osatelliteo ranges of the two above-mentioned groups.