Environmental and geographical determinants of beta diversity of leaf beetles (Coleoptera: Chrysomelidae) in the Iberian Peninsula

1. The effect and relative importance of both environmental and geographic factors on species turnover of Chrysomelidae assemblages in the Iberian Peninsula was explored. 2. Ordination and classification analysis of species lists from well-sampled local areas identified two main biogegraphic groups of inventories, discriminating between Eurosiberian and Mediterranean faunas. 3. After describing this pattern, the underlying determinants were explored, separating pure from combined effects of environment and geography by means of partial canonical correspondence analysis. 4. Results indicate that pure effects of environment and geographic position are of similar magnitude (about 20% of the variation from each), and quite important in comparison with combined effects. 5. The power of the pure effect of geographical variables, together with beta-diversity independence of species richness gradients, point to the inadequacy of environmental measurement explanation of beta-diversity patterns, and to the existence of a major component of geographical variation independent of environment.