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Not the most basal eukaryotes: challenges and pitfalls affecting the placement of Giardia and Trichomonas
Author(s) -
WALKER GISELLE,
EMBLEY T. MARTIN
Publication year - 2005
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.2005.05202003_1_79.x
Subject(s) - biology , trichomonas , giardia , trichomonas vaginalis , ribosomal rna , evolutionary biology , gene , genetics
Diplomonads (including Giardia ) and parabasalids (including Trichomonas ) have traditionally been seen as the deepest‐branching eukaryotes, on the evidence of apparently simple ultrastructural morphology, and small subunit ribosomal RNA trees. However, this position does not appear to be well supported, especially in the light of the discoveries of apparent mitochondrial remnants in Giardia and Trichomonas . We systematically re‐analysed protein data, and show here that their traditional placement may be due to a combination of factors acting on data sets (narrow taxon sampling) and on genes (rate heterogeneity and compositional heterogeneity, mutational saturation). Our data found no consistent support for either Giardia or Trichomonas being basal eukaryotes.