Dung beetle geographic diversity variation along a Western Iberian latitudinal transect (Coleoptera : Scarabaeidae)

To explore the richness and geographic turnover of dung beetle assemblages (Scarabaeinae and. Aphodiinae) inhabiting the Western Iberian peninsula, a latitudinal north-south transect was carried out in Portuguese territory. E stimators of alpha, beta, and gamma diversities were used, as well as the r atio Scarabaeinae/Aphodiinae, which puts into evidence some dung beetle com munity spatial characteristics. Clustering methods were also used to ascert ain relationships between biogeograghical Portuguese regions and geographic al patterns of species replacement. Although Scarabaeinae appears mainly re sponsible for overall and regional richness, Aphodiinae richness was rather low everywhere except for the southernmost plot of the transect investigat ed. The scarcity of Aphordiinae species is reflected in the Scarabaeinae/Ap hodiinae ratio, a score that is, however, clearly biased toward the Aphodii nae in almost all the Iberian Peninsula. For this reason the pairwise turno ver in species composition between sites is mainly determined by the variat ion in Scarabaeinae species. Peaks of beta-diversity, especially for Scarab aeinae, and clusters from dendrograms are highly consistent with physioclim atic subregions of Portugal, thus suggesting a correspondence between bioge ographic and environmental boundaries.