Evolutionary genetics of Trypanosoma and Leishmania

We review recent advances in the study of population structure and phylogen etic diversity of parasites belonging to the genera Trypanosoma and Leishma nia. In all species properly analyzed, these parasites exhibit a basically clonal population structure, with occasional bouts of genetic exchange or h ybridization, 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 stat us of some Leishmania 'species' is questionable. (C) Elsevier, Paris.