Congruence and indifference between two molecular markers for understanding oral evolution in the Marynidae sensu lato (Ciliophora, Colpodea).
Bottom Line: Our understanding of the evolution of oral structures within the Colpodida is confounded by the low number of morphological characters that can be used in constructing hypotheses, and by the low taxon and character sampling in molecular phylogenetic analyses designed to assess these hypotheses.We show that the inferred mitochondrial and nuclear SSU-rDNA trees, as well as concatenated and constrained analyses, are congruent in not recovering a monophyletic Marynidae.However, due to low node support, the trees are indifferent to whether the morphological characters used to unite the Marynidae are the result of retention of ancestral states or convergence.
Affiliation: Department of Ecology, University of Kaiserslautern, Germany. email@example.comShow MeSH
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Mentions: The tree of Foissner et al. (2011), which includes 12 Colpoda species, shows small and large Colpoda clades distributed over the entire Colpodida tree. For instance, there is a clade with Colpoda steinii and Bromeliothrix metopoides, although C. steinii is morphologically much more similar to C. aspera than to Bromeliothrix. The same applies for the C. aspera/Hausmanniella clade and the C. maupasi/C. augustini clade, which are far away from the Colpoda s.str. clade. Thus, Foissner et al. (2011) suggest a rapid basal radiation of the genus Colpoda, where the Colpoda stem species remained largely unchanged and repeatedly produced new taxa. This hypothesis explains the jumping appearance of clades with Colpoda species throughout the Colpodida tree and requires a new hypothesis on the origin of the Colpoda/Maryna oral apparatus (Fig. 4). The Colpoda stem species (“Ur-Colpoda”) should have been a small, bacterivorous ciliate, as are the last common ancestors, Cyrtolophosis and Bardeliella. Further, it should have had an oral apparatus similar to that of present-day colpodas s.str. These features are retained by several extant species, e.g., C. aspera and C. ecaudata.
Affiliation: Department of Ecology, University of Kaiserslautern, Germany. firstname.lastname@example.org