Résumé
We review recent advances in the study of population structure and phylogenetic diversity of parasites belonging to the genera
Trypanosoma and
Leishmania. In all species properly analyzed, these parasites exhibit a basically clonal population structure, with occasional bouts of genetic exchange or hybridization, and a strong structuration of their populations into discrete evolutionary lineages. On an evolutionary scale, the impact of sex appears to be greater in African than in American trypanosomes. The taxonomic status of some
Leishmania `species' is questionable.