Phylogenetic position of the kinetoplastids, Cryptobia bullocki, Cryptobia catostomi, and Cryptobia salmositica and monophyly of the genus Trypanosoma inferred from small subunit ribosomal RNA sequences

Kinetoplastid phylogenetics, with special reference to the evolution of parasitic trypanosomes

“…E-mail: j.r.stevens@ex.ac.uk 2000) and even in those parasites of medical importance, it is little more than a decade since the widespread introduction of DNA sequencing technologies has allowed the evolution of parasitic trypanosomatids (and kinetoplastids in general) to be evaluated by formal phylogenetic analysis (Fernandes et al, 1993;Alvarez et al, 1996;Maslov et al, 1996;Lukes et al, 1997;Haag et al, 1998;Hannaert et al, 1998;Stevens et al, 1999Stevens et al, , 2001Wright et al, 1999;Hamilton et al, 2004;Moreira et al, 2004). To fully understand the evolutionary history of parasitic kinetoplastids and to understand the context within which the evolution of each parasite group has unfolded, an understanding not just of the parasites, but also of broader kinetoplastid phylogenetics is required.…”

“…A monophyletic group consists of taxa that are descended from a single common ancestor and contains all known descendants from that ancestor. The first molecular phylogenetic studies, based on comparisons of mitochondrial and nuclear ribosomal DNAs (rDNA), showed trypanosomes to be paraphyletic (Gomez et al, 1991;Fernandes et al, 1993;Maslov et al, 1996), while subsequent rDNA-based studies, which have included more taxa from a far broader range of host species (Lukes et al, 1997;Stevens et al, 1999Stevens et al, , 2001Wright et al, 1999;Simpson et al, 2002;Hamilton et al, 2004) (Fig. 2) supported monophyly.…”

Future trypanosomatid phylogenies: refined homologies, supertrees and networks

“…For example, Stevens and Gibson (1999) infer Crithidia to be a monophyletic sister taxon of Leishmania. This clear relationship was split, however, by Wright et al (1999). C. fasciculata and C. oncopelti were more ambiguously placed as sister taxa of Leptomonas sp.…”

“…Noyes (1998) expanded upon the taxonomic coverage of the 18S data and stimulated much debate both in biogeographic implications (Stevens & Gibson 1998) and methodology of inference from these data (Maslov & Lukes 1998, Noyes & Rambaut 1998. Further taxon sampling led to the cladograms reported by Stevens and Gibson (1999) and Wright et al (1999). Through the use of biogreographic vicariance, Stevens and Gibson (1999) were able to relate the evolutionary patterns with that of continental drift and dispersal of early hominids.…”

“…Whilst the cladograms of Stevens and Gibson (1999) and Wright et al (1999) have a degree of congruence, there are some interesting anomalies that require consideration. For example, Stevens and Gibson (1999) infer Crithidia to be a monophyletic sister taxon of Leishmania.…”