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Phylogeny of Opisthokonta and the evolution of multicellularity and complexity in Fungi and Metazoa

2003; Cambridge University Press; Volume: 2; Issue: 3 Linguagem: Inglês

10.1017/s1473550403001551

1475-3006

Mónica Medina, Allen G. Collins, John W. Taylor, James W. Valentine, Jere H. Lipps, Linda Amaral‐Zettler, Mitchell L. Sogin,

Marine Biology and Ecology Research

While early eukaryotic life must have been unicellular, multicellular lifeforms evolved multiple times from protistan ancestors in diverse eukaryotic lineages. The origins of multicellularity are of special interest because they require evolutionary transitions towards increased levels of complexity. We have generated new sequence data from the nuclear large subunit ribosomal DNA gene (LSU rDNA) and the SSU rDNA gene of several unicellular opisthokont protists – a nucleariid amoeba ( Nuclearia simplex ) and four choanoflagellates ( Codosiga gracilis , Choanoeca perplexa , Proterospongia choanojuncta and Stephanoeca diplocostata ) to provide the basis for re-examining relationships among several unicellular lineages and their multicellular relatives (animals and fungi). Our data indicate that: (1) choanoflagellates are a monophyletic rather than a paraphyletic assemblage that independently gave rise to animals and fungi as suggested by some authors and (2) the nucleariid filose amoebae are the likely sister group to Fungi. We also review published information regarding the origin of multicellularity in the opisthokonts.