Evaluating molecular support for and against the monophyly of the Peritrichia and phylogenetic relationships within the Mobilida (Ciliophora, Oligohymenophorea)

Abstract

Evaluating molecular support for and against the monophyly of the Peritrichia and phylogenetic relationships within the Mobilida (Ciliophora, Oligohymenophorea). -Zoologica Scripta, 42, 213-226. An ongoing debate in ciliate molecular phylogenetic analyses is whether the Peritrichiacomposed of the Sessilida and the Mobilida -are monophyletic. To further investigate this group, here we increase taxon sampling with four further mobilids: Trichodinella sp., Trichodina pectenis, Urceolaria serpularum and Urceolaria korschelti. Results show that support for and against monophyly of the peritrichs depends on different methods of alignment, and different methods of masking ambiguously aligned nucleotide positions. Results from constrained analyses also are dependent on different alignment and masking methods. We propose that there is no well-supported SSU-rDNA evidence supporting for and against the removal of the mobilids from the peritrichs. Within the Mobilida, we find that Trichodinella nest within Trichodina, Urceolaria branch basally, and Trichodina are non-monophyletic, and suggest that Leiotrocha be formally transferred into Urceolaria. In addition, the data support that Urceolaria-like denticles and Urceolaria-⁄ Trichodina-like adoral ciliary spiral are plesiomorphic conditions within the mobilids.

New Comparative Analysis Based on the Secondary Structure of SSU-rRNA Gene Reveals the Evolutionary Trend and the Family-Genus Characters of Mobilida (Ciliophora, Peritrichia)

“…On one hand, its secondary structure is consistent with the Urceolariidae within the Helix 12 and Helix 37, and on the other hand, it resembles the Trichodinidae within other regions. From another aspect, T. hypsilepis clustered in one separate clade within the phylogenic tree here and the analogous trees ever reported before [21].Therefore, the research results above indicated that T. hypsilepis probably evolved independently within family Trichodinidae. Nevertheless, the data of secondary structure seemed to be detrimental to ascertain taxonomic status of T. hypsilepis in the genus Trichodina, because another important reason is that no data about the morphological material for T. hypsilepis available which could conform to its molecular sequence up date; besides, in the phylogenic tree, it diverged before all the other species of genus Trichodina but after the Urceolaria.…”

“…Meanwhile, if no identification errors happened on T. hypsilepis, the genus Trichodina should be the more ancestral group compared with genus Trichodinella. Combined with the other biological character, Urceolariidae species have more primitive adhesive disk with very undeveloped denticles in morphology, and they are always found to parasitize on invertebrates rather than vertebrates, which is distinctly different from Trichodinidae ones parasitic on fishes and amphibians except those invertebrates [21]. Therefore, the secondary structure of V6 has proved the family Urceolariidae primitive status with the additional evidence.…”

“…However, for researching the evolutionary history of Mobilida ciliates, only the morphological characters have proved inadequate [4]. In recent years, a few of molecular works have been carried out to reveal the relationship within the Mobilida [5,6,15,21]. Although the molecular data, mainly the primary structure of nucleotide, could be used to study the phylogenic analyses of Mobilida ciliates, some important evolutionary information, such as the evolutionary trend, could not be provided by the primary structure of nucleotide.…”

Phylogenomics solves a long-standing evolutionary puzzle in the ciliate world: The subclass Peritrichia is monophyletic

“…Thus, Zhan et al (2009) proposed that the mobilids be separated from the sessilids and established as the new subclass Mobilia. Zhan et al (2013) increased the sample size of mobilids and successfully recovered peritrichs as monophyletic; however this relationship had no statistical support.…”

The Epidemiology of the Trichodinid Ciliate <i>Trichodina truttae</i> on Hatchery-reared and Wild Salmonid Fish in Hokkaido

“…Partial SSUrDNA nucleotide sequences of nine Trichodina species and two Trichodinella species (family Trichodinidae) were obtained from the Genbank database under the following accession numbers: T. ; T. pectenis (JQ663868: Zhan et al, 2013); and T. sinipercae (EF599288). A multiple sequence alignment analysis was performed, and a phylogenetic tree was constructed using the neighbor-joining method and ClustalW ver.…”