Shalchian-Tabrizi Kamran, Kauserud Håvard, Massana Ramon, Klaveness Dag, Jakobsen Kjetill S
Department of Biology, Centre for Ecological and Evolutionary Synthesis, University of Oslo, N-0316 Oslo, Norway.
Protist. 2007 Apr;158(2):173-80. doi: 10.1016/j.protis.2006.10.003. Epub 2006 Dec 29.
Telonemia has recently been described as a new eukaryotic phylum with uncertain evolutionary origin. So far, only two Telonemia species, Telonema subtilis and Telonema antarcticum, have been described, but there are substantial variations in size and morphology among Telonema isolates and field observations, indicating a hidden diversity of Telonemia-like species and populations. In this study, we investigated the diversity and the global distribution of this group by analyzing 18S rDNA sequences from marine environmental clone libraries published in GenBank as well as several unpublished sequences from the Indian Ocean. Phylogenetic analyses of the identified sequences suggest that the Telonemia phylum includes several undescribed 18S rDNA phylotypes, probably corresponding to a number of different species and/or populations. The Telonemia phylotypes form two main groups, here referred to as Telonemia Groups 1 and 2. Some of the closely related sequences originate from separate oceans, indicating worldwide distributions of various Telonemia phylotypes, while other phylotypes seem to have limited geographical distribution. Further investigations of the evolutionary relationships within Telonemia should be conducted on isolated cultures of Telonema-like strains using multi-locus sequencing and morphological data.
纤毛门最近被描述为一个进化起源不明的新真核生物门。到目前为止，仅描述了两种纤毛门物种，即纤细纤毛虫和南极纤毛虫，但纤毛虫分离株和野外观察结果在大小和形态上存在很大差异，这表明类似纤毛门的物种和种群存在隐藏的多样性。在本研究中，我们通过分析来自GenBank中公布的海洋环境克隆文库的18S rDNA序列以及来自印度洋的一些未公布序列，研究了该类群的多样性和全球分布。对已鉴定序列的系统发育分析表明，纤毛门包括几个未描述的18S rDNA系统型，可能对应于许多不同的物种和/或种群。纤毛门系统型形成两个主要类群，这里称为纤毛门第1组和第2组。一些密切相关的序列来自不同的海洋，表明各种纤毛门系统型在全球范围内分布，而其他系统型似乎地理分布有限。应使用多位点测序和形态学数据，对类似纤毛虫菌株的分离培养物进行纤毛门内进化关系的进一步研究。
