Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain.
Mol Biol Evol. 2013 Apr;30(4):802-5. doi: 10.1093/molbev/mst006. Epub 2013 Jan 16.
The Opisthokonta clade includes Metazoa, Fungi, and several unicellular lineages, such as choanoflagellates, filastereans, ichthyosporeans, and nucleariids. To date, studies of the evolutionary diversity of opisthokonts have focused exclusively on metazoans, fungi, and, very recently, choanoflagellates. Thus, very little is known about diversity among the filastereans, ichthyosporeans, and nucleariids. To better understand the evolutionary diversity and ecology of the opisthokonts, here we analyze published environmental data from nonfungal unicellular opisthokonts and report 18S ribosomal DNA phylogenetic analyses. Our data reveal extensive diversity among all unicellular opisthokonts, except for the filastereans. We identify several clades that consist exclusively of environmental sequences, especially among ichthyosporeans and choanoflagellates. Moreover, we show that the ichthyosporeans represent a significant percentage of overall unicellular opisthokont diversity, with a greater ecological role in marine environments than previously believed. Our results provide a useful phylogenetic framework for future ecological and evolutionary studies of these poorly known lineages.
后口动物包括后生动物、真菌以及几个单细胞谱系，如领鞭毛虫、有孔虫、鱼卵菌和核形虫。迄今为止，对后口动物进化多样性的研究仅集中在后生动物、真菌，以及最近的领鞭毛虫上。因此，人们对有孔虫、鱼卵菌和核形虫的多样性知之甚少。为了更好地了解后口动物的进化多样性和生态学，我们分析了已发表的非真菌单细胞后口动物的环境数据，并报告了 18S 核糖体 DNA 系统发育分析。我们的数据显示，除了有孔虫之外，所有的单细胞后口动物都具有广泛的多样性。我们确定了几个仅由环境序列组成的进化枝，特别是在鱼卵菌和领鞭毛虫中。此外，我们表明，鱼卵菌在单细胞后口动物的总体多样性中占相当大的比例，其在海洋环境中的生态作用比以前认为的要大。我们的研究结果为今后对这些了解甚少的谱系进行生态和进化研究提供了有用的系统发育框架。
