Early evolution of eukaryotes inferred from genome data

Abstract

Phylogenetic relationships among major eukaryotic lineages including amitochondriate protists were analyzed by applying combined maximum likelihood (ML) method to the multiple molecular sequence data. At first, phylogenetic position of one group of amitochondriate protists called Microsporidia was analyzed. The combined ML analysis using eight genes demonstrated a relationship (Metazoa,(Fungi, Microsporidia)) with a high statistical support. In the next, another combined ML analysis was performed to examine the relationship between stramenopiles and Alveolata, using eight genes. The analysis demonstrated that these two groups are the closest relatives. In the last, the position of the Pelobiont Mastigamoeba balamuthi was analyzed. A combined ML analysis using 13 genes suggested that M. balamuthi is the closest relative of Entamoeba histolytica and that Mycetozoa were placed at the sister-group to the M. balamuthi/ E. histolytica clade. These findings suggest that both M. balamuthi and E. histolytica are closely related to the Mycetozoa and that these three together represent a major eukaryotic lineage called Conosa.