Phylogenomic Analysis of Protozoa
The protozoa are an enigmatic group of single-celled eukaryotes forming the earliest-diverging lineages in Eukarya. Protozoa are particularly notable as pathogens and parasites, causing a variety of diseases of insects, fish, birds, and mammals - including humans. For example, malaria is caused by a number of Plasmodium species, most importantly Plasmodium falciparum.
We are developing a phylogenomic approach to examine the evolution of pathogenicity within the protozoa. This approach aims at addressing a number of critical questions in the evolution of host-pathogen evolution, such as: What are proteins responsible for the evolution of pathogenicity, and are these proteins conserved in different pathogens? How do these proteins interact with molecules in the host to cause disease? What are the genomic consequences of the evolution of pathogenicity for the pathogen and for the host?
A thorough understanding of the evolution of pathogenicity within the protozoa begins with a detailed map of how these species have evolved. Unfortunately, unravelling the species phylogeny of the protozoa is especially challenging for a number of reasons. First, the earliest branches of the eukaryotic tree are ancient (Eukarya diverged - probably from Archaea - approximately 2300 Mya). Second, the diversification of early protozoa happened relatively quickly (in geologic time), and finally, the parasitic lifestyle of many protozoa causes them to evolve very quickly, as they are under strong selection pressures created by the host's immune system.
We are exploiting the availability of whole-genome sequences from a variety of protozoa to build a robust and high-resolution phylogeny of these important organisms. By better understanding the evolution of protozoa, we hope to shed new light on the diversity of mechanisms responsible for a multitude of human diseases.