Ref ID : 7118
Micah Dunthorn, Wilhelm Foissner, and Laura A. Katz; Expanding Character Sampling for Ciliate Phylogenetic Inference Using Mitochondrial SSU-rDNA as a Molecular Marker. Protist 162:85-99, 2011
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Molecular systematics of ciliates, particularly at deep nodes, has largely focused on increasing taxon sampling using the nuclear small subunit rDNA (nSSU-rDNA) locus. These previous analyses have generally been congruent with morphologically-based classifications, although there is extensive non-monophyly at many levels. However, caution is needed in interpreting these results as nSSU-rDNA is just a single molecular marker. Here the mitochondrial small subunit rDNA (mtSSU-rDNA) is evaluated for deep ciliate nodes using the Colpodea as an example. Overall, well-supported nodes in the mtSSU-rDNA and concatenated topologies are well supported in the nSSU-rDNA topology; e.g., the non-monophyly of the Cyrtolophosidida. The two moderately-to well-supported incongruences between the loci are the placement of the Sorogenida and Colpoda aspera. Our analyses of mtSSU-rDNA support the conclusion, originally derived from nSSU-rDNA, that the morpological characters used in taxonomic circumscriptions of the Colpodea represent a mixture of ancestral and derived states. This demonstration of the efficacy of the mtSSU-rDNA will enable phylogenetic reconstructions of deep nodes in the ciliate tree of life to move from a single-locus to a multi-locus approach.