Figure 2. The evolution of microsporidian nucleotide transport proteins is characterized by an initial horizontal acquisition of a single gene followed by lineage-specific gene duplications.

A phylogeny of NTT proteins for the microsporidian/Rozella clade of endoparasitic fungi and representative bacterial intracellular pathogens including Chlamydia and Rickettsia. The tree suggests a single common origin for NTT proteins in Rozella and microsporidians followed by the lineage- and clade-specific gene duplications that define microsporidian NTT protein evolution. The different clades of microsporidians were defined previously [26]. A similar pattern of repeated gene duplication is evident in the tree for bacterial proteins. Values at nodes are Bayesian posterior probabilities.