Molecular Phylogeny of Tintinnid Ciliates (Ciliophora: Tintinnida) Based On Multiple Genes Analyses

Abstract

Systematics and phylogeny of tintinnid ciliates (Ciliophora: Tintinnida) have always been difficult due to the known polymorphism of the lorica and the lack of infraciliature information of the zooids. Thus, it is necessary and important to deduce their relationships based on combined evidences from both morphology and gene sequences. Although molecular approaches have been increasingly employed to construct ciliate phylogeny, the phylogeny of tintinnids is still at very early stage which is mainly because of insufficient taxon sampling and using single molecular marker that has greatly hindered advances in determining the evolutionary relationships in this species-rich group. From the beginning of 2011, tintinnid samples were collected from different locations along Korea coastal waters (e.g. Gwangyang Bay, Jinhae Bay, Jangmok Bay), the Yellow Sea, and East China Sea. Totally, we sorted out 60 tintinnid samples which belong to 30 species representing 15 genera and three genes coding for SSU rDNA, ITS1-5.8S-ITS2, and LSU rDNA of all these tintinnids were amplified and sequenced. Phylogenetic analyses of all sequences available tintinnids were performed using various methods. This is the first time to elucidate tintinnid phylogeny based on multi-genes analyses. Our results showed the following: (1) The status of Coxliella, which was considered as a “questionable” genus, was validant to deduce their relationships based on combined evidences from both morphology and gene sequences. Although molecular approaches have been increasingly employed to construct ciliate phylogeny, the phylogeny of tintinnids is still at very early stage which is mainly because of insufficient taxon sampling and using single molecular marker that has greatly hindered advances in determining the evolutionary relationships in this species-rich group. From the beginning of 2011, tintinnid samples were collected from different locations along Kor