Phylogeny and evolution of the piroplasms

Area of Science:

• Molecular Phylogenetics
• Parasitology
• Genomics

Background:

• Theileria, Cytauxzoon, and Babesia are important tick-borne protozoan parasites.
• Understanding their evolutionary relationships is crucial for disease control and prevention.
• Small subunit ribosomal RNA (srRNA) genes are valuable markers for phylogenetic studies.

Purpose of the Study:

• To investigate the phylogenetic relationships among Theileria, Cytauxzoon, and Babesia species.
• To clarify the evolutionary origins of these tick-borne parasites using molecular data.

Main Methods:

• Amplification, cloning, and sequencing of small subunit ribosomal RNA (srRNA) genes.
• Phylogenetic tree construction using four independent methods (distance, parsimony, maximum likelihood).
• Alignment with srRNA sequences from other Apicomplexa, ciliate, and dinoflagellate species.

Main Results:

• Phylogenetic trees did not consistently show a single branching order.
• Theileria species formed a monophyletic group, originating from a paraphyletic group including certain Babesia species (B. equi, C. felis, B. rodhaini).
• Distance trees indicated that Babesia sensu stricto species form a monophyletic group that diverged before Theileria separation; parsimony and maximum likelihood trees suggest Babesia and Theileria are sister taxa.

Conclusions:

• The study provides insights into the evolutionary history of Theileria and Babesia.
• The findings suggest a complex evolutionary trajectory with potential polyphyletic origins for some groups.
• Further research is needed to resolve the precise phylogenetic relationships within these important parasite genera.