1887

Abstract

The phylogenetic position of Cryptosporidium is elusive. Although previous studies based solely upon small-subunit (SSU) rRNA sequences suggested that the genus was an early emerging lineage among the Apicomplexa, bootstrap support for this placement was low. Here, the phylogenetic position of Cryptosporidium has been re-evaluated for SSU rRNA, fused SSU/large-subunit (LSU) rRNA and six protein sequences using traditional distance-based neighbour-joining, maximum-parsimony and maximum-likelihood methods of phylogenetic reconstruction as well as the new Slow-Fast analysis, which focuses upon the slowly evolving positions within sequences and is especially useful if a long-branch attraction (LBA) artefact is suspected. All the methods of reconstruction indicated a trend for the early emergence of Cryptosporidium at the base of the Apicomplexa and showed that an LBA artefact plays no role in this placement. Although the inclusion of additional numbers of neither species nor genes has significantly enhanced the bootstrap support for this phylogenetic position, recent biochemical, molecular and ultrastructural data are congruent with it. Therefore, we favour a working hypothesis that this genus constitutes an early emerging branch of the Apicomplexa.

Loading

Article metrics loading...

/content/journal/ijsem/10.1099/00207713-50-4-1673
2000-07-01
2019-11-21
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/journal/ijsem/10.1099/00207713-50-4-1673
Loading

Most Cited This Month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error