ECOLOGY AND BIOGEOGRAPHY OF DUNG-BEETLE COMMUNITIES (COLEOPTERA, SCARABAEOIDEA) IN AN IBERIAN MOUNTAIN-RANGE

The role of the Eastern Mountains of the Iberian Central System (EMICS ) as both a barrier to the dispersion of, and ecologic refuge for, Sca rabaeoidea dung beetles is studied. An Ecogeographic Patterns comparis on method (EP = set of ecologic features common to, and present geogra phic range shared by, a group of species) to weight the historical and ecological causes of geographic distribution is proposed. This method is based on the assumption that species now sharing geographic ranges , with common structural and nonstructural features, also have a (to s ome extent) common evolutionary history. The data studied indicate tha t (i) fauna of the N and S slopes are identical. Euroturanian and Medi terranean species, and those which belong to the Scarabaeidae family, predominated in all samples. Except for very few species, the EMICS ha ve not impeded dispersal of Scarabaeoidea dung beetles; minor regional differences should be explained in terms of ecological causes. (ii) T he variation in abundance, richness, characteristic species, systemati c composition and EP was found to relate mainly with altitude. Princip ally endemic, European or wider-range species of the Aphodiidae and Ge otrupidae families, prevented from dispersing toward lower altitudes b y a climatic discontinuity, colonize the higher altitudes, having take n refuge in the EMICS after Pleistocene glaciations. (iii) The explana tion of the causes of the present vertical distribution of Scarabaeoid ea dung beetles in the EMICS must take into account the historical eve nts there, and major modifications of the geographic distribution of t he species inhabiting it. The agreement of inferences drawn from EP an alysis with those drawn from paleontologic and phylogenetic evidence ( for some species) supports the use of EP, and validates the assumption made in their application.