The Protistan Origins Of Animals and Fungi

Fungi and Metazoa (animals) are two major multicellular kingdoms of life and both are positioned in the eukaryotic Opisthokonta. Within the supergroup Fungi and Metazoa fall into either side of the opisthokont root, in the major sub-groups Holomycota and Holozoa. In this chapter, we cover recent advances in the understanding of opisthokont biology, in particular looking at their diversity and where opisthokonts fall in the eukaryotic tree. Although much uncertainty remains over how different eukaryotic supergroups are related to each other, the closest relatives of Opisthokonta are now widely recognised.

The composition of Opisthokonta has been revised due to the discovery of new species, as well as the reassignment of taxa on the basis of phylogenetic analyses. We consider common traits and characteristics found in opisthokonts. The explosion of genomic and transcriptomic sequencing since the turn of the century has allowed the identification of genes involved in multicellularity in both Metazoa and Fungi; molecular phylogenies show multicellularity has independently evolved in multiple lineages across the opisthokonts. Annotated gene complements from species spanning the group highlight that gene loss and gain is a dynamic process in the opisthokonts.