Insights into the phylogeny of sporadotrichid ciliates (Protozoa, Ciliophora: Hypotricha) based on genealogical analyses of multiple molecular markers  

作　　者：胡晓燕 胡晓钟 Khaled A.S.AL-RASHEID Saleh A.AL-FARRAJ 宋微波 

机构地区：[1]Laboratory of Protozoology,Institute of Evolution and Marine Biodiversity,Ocean University of China [2]Department of Zoology,Natural History Museum [3]Zoology Department,King Saud University

出　　处：《Chinese Journal of Oceanology and Limnology》2011年第1期96-102,共7页中国海洋湖沼学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China (No. 30870264, 40976075);a grant from the Center of Excellence in Biodiversity, King Saud University;a Marie Curie Incoming International Fellowship within the 7th European Community Framework Programme

摘　　要：The sporadotrichid ciliates are an especially diverse group. A number of investigators have studied the morphological, morphogenetic, and molecular relationships among members of this group. Despite this, a consistent classification is still lacking and several important questions about the phylogenetic relationships within this group remain unsolved. To improve our understanding of these relationships, we constructed phylogenetic trees using the nucleotide sequences of the small-subunit rRNA (SSrRNA) gene and amino acid sequences of actin I and α-tubulin. Analyses of SSrRNA gene sequences indicated that: 1) the Sporadotrichida sensu Lynn (2008) and the Oxytrichidae are polyphyletic; 2) the Uroleptus species, which are classified to urostylids, formed a sister group with the oxytrichids; 3) Halteria grandinella, which is grouped morphologically with oligotrich species, clustered within the oxytrichids. These results are congruent with previous studies based on SSrRNA gene sequences. However, the amino acid sequences of actin I and α-tubulin yielded different topologies. The main results are: 1) in all phylogenetic trees, the genus Oxytricha was paraphyletic; 2) Uroleptus was sister to a subset of Urostyla and Holosticha, albeit with low supporting values; 3) Halteria grandinella was separated distantly from the Oxytrichidae in trees inferred from actin I amino acid sequences but clustered with oligotrichids in the α-tubulin analysis. The inconsistency among the trees inferred from these different molecular markers may be caused by rapidly accumulated genetic characterizations of ciliates. Further studies with additional molecular markers and sampling of more taxa are expected to better address the relationships among sporadotrichids.The sporadotrichid ciliates are an especially diverse group. A number of investigators have studied the morphological, morphogenetic, and molecular relationships among members of this group. Despite this, a consistent classification is still lacking and several important questions about the phylogenetic relationships within this group remain unsolved. To improve our understanding of these relationships, we constructed phylogenetic trees using the nucleotide sequences of the small-subunit rRNA （SSrRNA） gene and amino acid sequences of actin I and α-tubulin. Analyses of SSrRNA gene sequences indicated that： 1） the Sporadotrichida sensu Lynn （2008） and the Oxytrichidae are polyphyletic; 2） the Uroleptus species, which are classified to urostylids, formed a sister group with the oxytrichids; 3） Halteria grandinella, which is grouped morphologically with oligotrich species, clustered within the oxytrichids. These results are congruent with previous studies based on SSrRNA gene sequences. However, the amino acid sequences of actin I and α-tubulin yielded different topologies. The main results are： 1） in all phylogenetic trees, the genus Oxytricha was paraphyletic; 2） Uroleptus was sister to a subset of Urostyla and Holosticha, albeit with low supporting values; 3） Halteria grandinella was separated distantly from the Oxytrichidae in trees inferred from actin I amino acid sequences but clustered with oligotrichids in the α-tubulin analysis. The inconsistency among the trees inferred from these different molecular markers may be caused by rapidly accumulated genetic characterizations of ciliates. Further studies with additional molecular markers and sampling of more taxa are expected to better address the relationships among sporadotrichids.

关 键 词：sporadotrichid ciliates PHYLOGENY SSRRNA actin I ALPHA-TUBULIN amino acid sequences 

分 类 号：Q951.3[生物学—动物学]