A molecular phylogeny of the Microsporida

Abstract

The molecular phylogenetics of the Microsporida were investigated using small subunit ribosomal RNA gene sequence data. The small subunit ribosomal RNA gene was sequenced and aligned for 27 species from 18 genera and analyzed using various eukaryotic, eubacterial, and archaebacterial sequences as outgroups. Maximum parsimony, maximum likelihood, and distance based methods were used to analyze the data producing highly supported results based on bootstrap and decay analyses. According to the analysis, the species examined can be divided into five major monophyletic groups. The Amblyospora group represents the basal lineage of the microsporidia examined. The genera included in this taxon (Amblyospora, Parathelohania, Edhazardia, and Culicosporella) are all parasites of mosquitos. The next group to come off of the tree is the Ichthyosporidium group. The Ichthyosporidium group, being comprised of species infecting a variety of hosts found in a variety of habitats, represents one of the more diverse groups with respect to parasite ecology. Genera included in this group are Vavraia, Ichthyosporidium, Pleistophora, Glugea, Spraguea, Ameson, and Abelspora. The Endoreticulatus group represents the third group to come off of the tree. This group contains the genera Enterocytozoon, Vittaforma, and Endoreticulatus. The final two groups, Encephalitozoon and Vairimorpha/Nosema groups, form a monophyletic taxon. The molecular phylogenies were compared to the modern taxonomic systems of the microsporidia and used to examine the evolutionary patterns of a number of morphological and ecological character states.