Phylogenomics unravels the early diversification of fungi

Abstract

Phylogenomic analyses have boosted our understanding of the evolutionary trajectories of all living forms by providing continuous improvements to the tree of life1-5. Within this tree, fungi represent an ancient eukaryote group6, having diverged from the animals [~]1.35 billion years ago7. Estimates of the number of extant species range between 1.5 and 3.8 million8,9. Recent reclassifications and the discovery of the deep-branching Sanchytriomycota lineage10 have brought the number of proposed phyla to 2011; 21 if the Microsporidia are included12-14. Uncovering how the diverse and globally distributed fungi are related to each other is fundamental for understanding how their lifestyles, morphologies, and metabolic capacities evolved. To date, many of the proposed relationships among the phyla remain controversial and no phylogenomic study has examined the entire fungal tree using a taxonomically comprehensive data set and suitable models of evolution. We assembled and curated a 299-protein data set with a taxon sampling broad enough to encompass all recognised fungal diversity with available data, but selective enough to run computationally intensive analyses using best-fitting models. Using a range of reconstruction methods, we were able to resolve many contested nodes, such as a sister-relationship of Chytridiomyceta to all other non-Opisthosporidia fungi (with Chytridiomycota being sister to Monoblepharomycota + Neocallimastigomycota), a branching of Blastocladiomycota + Sanchytriomycota after the Chytridiomyceta but before other non-Opisthosporidia fungi, and a branching of Glomeromycota as sister to the Dikarya. Our most up-to-date fungal tree of life will serve as a springboard for future investigations on the evolution of fungi.