Multigene Phylogeny of Choanozoa and the Origin of Animals

摘要: Animals are evolutionarily related to fungi and the predominantly unicellular protozoan phylum Choanozoa, together known as opisthokonts. To establish sequence of events when animals evolved from ancestors, understand those key evolutionary transitions, we need which choanozoans most closely also position each choanozoan group within opisthokont phylogenetic tree. Here focus on Ministeria vibrans, a minute bacteria-eating cell with slender radiating tentacles. Single-gene trees suggested that it is either closest relative or else sister choanoflagellates, traditionally considered likely animal ancestors. Sequencing thousands protein genes now reveals about 14 domains significance for biology, including several previously unknown deeply diverging e.g. involved in hedgehog, Notch tyrosine kinase signaling adhesion (cadherin). Phylogenetic using 78 proteins show not choanoflagellates (themselves sisters animals), but Capsaspora, another thread-like (filose) The Ministeria/Capsaspora clade (new class Filasterea) these three groups forming novel (filozoa) whose ancestor presumably filose tentacles well before they aggregated periciliary collar choanoflagellate/sponge common ancestor. Our ichthyosporean filozoa; fusion between ubiquitin ribosomal small subunit S30 unifies all holozoa (filozoa plus Ichthyosporea), being absent earlier branching eukaryotes. Thus, successive innovations occurred among their relatives prior origin multicellular body-plan animals.