Entamoeba, giardia and toxoplasma: clones or cryptic species?

The availability of molecular markers has renewed interest in the taxonomy of parasitic protozoa at the subspecific and specific levels. Nevertheless, the conclusions reached are heavily dependent upon the way the data are analyzed. Some authors have emphasized the value of genetic distances to propose the creation o f new species, while others have rather favoured a population genetic approach to account for the intraspecific variability of parasites. In this article, using three illustrative cases, Michel Tibayrenc shows that dissimilar taxonomic approaches can be built from quite comparable sets of data.