SANTA-ROSALIA REVISITED - OR WHY ARE THERE SO MANY KINDS OF PARASITESIN THE GARDEN OF EARTHLY DELIGHTS

As is the case for free-living species, a very large number of parasit ic species are not described adequately by the biological species conc ept. Furthermore, Thierry de Meeus, Yannis Michalakis and Francois Ren aud argue that because hosts represent a highly heterogeneous and chan ging environment as well as a breeding site, favouring the association of host-adaptation and host-choice genes, sympatric speciation may oc cur frequently in parasitic organisms. Therefore, parasites appear to be ideal biological models for the study of ecological specialization and speciation. Beyond the relevance of such considerations in fundame ntal science, the study of the origin and evolution of parasite divers ity has important implications for more applied fields such as epidemi ology and diagnosis.