The analysis of protein coding genes suggests monophyly of Trypanosoma

We analyze evolutionary relationships among members of the family Trypanosomatidae, with particular emphasis on whether protein coding genes support paraphyly of the genus Trypanosoma. Phylogenetic reconstruction based on three different protein coding genes (glyceraldehyde-3-phosphate dehydrogenase, trypanothione reductase, and alpha-tubulin) suggests that Trypanosoma is monophyletic. Moreover, pairwise comparisons of other protein coding genes show that the distances between Trypanosoma cruzi and T. brucei are significantly smaller than are the distances between each Trypanosoma species and Crithidia or Leishmania. These results contradict recent published phylogenies based on nuclear rRNA genes which suggest that T. cruzi is more closely related to Leishmania and Crithidia than to T. brucei. (C) 1996 Academic Press, Inc.