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The protistan origins of animals and fungi

Steenkamp, E.T., Wright, J. and Baldauf, S.L. (2006) The protistan origins of animals and fungi. Molecular Biology and Evolution, 23 (1). pp. 93-106. ISSN 0737-4038

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Recent molecular studies suggest that Opisthokonta, the eukaryotic supergroup including animals and fungi, should be expanded to include a diverse collection of primitively single-celled eukaryotes previously classified as Protozoa. These taxa include corallochytreans, nucleariids, ministeriids, choanoflagellates, and ichthyosporeans. Assignment of many of these taxa to Opisthokonta remains uncorroborated as it is based solely on small subunit ribosomal RNA trees lacking resolution and significant bootstrap support for critical nodes. Therefore, important details of the phylogenetic relationships of these putative opisthokonts with each other and with animals and fungi remain unclear. We have sequenced elongation factor 1-alpha (EF-1), actin, ß-tubulin, and HSP70, and/or -tubulin from representatives of each of the proposed protistan opisthokont lineages, constituting the first protein-coding gene data for some of them. Our results show that members of all opisthokont protist groups encode a 12-amino acid insertion in EF-1, previously found exclusively in animals and fungi. Phylogenetic analyses of combined multigene data sets including a diverse set of opisthokont and nonopisthokont taxa place all of the proposed opisthokont protists unequivocally in an exclusive clade with animals and fungi. Within this clade, the nucleariid appears as the closest sister taxon to fungi, while the corallochytrean and ichthyosporean form a group which, together with the ministeriid and choanoflagellates, form two to three separate sister lineages to animals. These results further establish Opisthokonta as a bona fide taxonomic group and suggest that any further testing of the legitimacy of this taxon should, at the least, include data from opisthokont protists. Our results also underline the critical position of these "animal-fungal allies" with respect to the origin and early evolution of animals and fungi.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: York RAE Import
Date Deposited: 20 Mar 2009 16:52
Last Modified: 20 Mar 2009 16:52
Published Version: http://dx.doi.org/10.1093/molbev/msj011
Status: Published
Publisher: Oxford University Press
Identification Number: 10.1093/molbev/msj011
URI: http://eprints.whiterose.ac.uk/id/eprint/7026

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