Expanding character sampling for ciliate phylogenetic inference using mitochondrial SSU-rDNA as a molecular marker.
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 andColpoda aspera.Our analyses of mtSSU-rDNA support the conclusion, originally derived from nSSU-rDNA, that the morphological 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.
Dunthorn
Micah
M
University of Massachusetts, Amherst, MA 01003, USA. dunthom@rhrk.uni-kl.de
Foissner
Wilhelm
W
Katz
Laura A
LA
D016798:Ciliophora / Q000145:classification* / Q000235:genetics* / Q000648:ultrastructure; D004275:DNA, Ribosomal / Q000235:genetics*; D019143:Evolution, Molecular; D005819:Genetic Markers; D008928:Mitochondria / Q000235:genetics*; D010802:Phylogeny
D004275:DNA, Ribosomal; D005819:Genetic Markers