Caisová Lenka, Marin Birger, Sausen Nicole, Pröschold Thomas, Melkonian Michael
Institute of Botany v.v.i., Academy of Sciences of the Czech Republic, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 31, CZ - 370 05 České Budějovice, Czech RepublicBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, GermanyDepartment Limnology, University of Vienna, Althanstr. 14, A-1090 Vienna, AustriaBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany.
J Phycol. 2011 Feb;47(1):164-77. doi: 10.1111/j.1529-8817.2010.00949.x. Epub 2011 Jan 13.
Previously published molecular phylogenetic analyses of the Chaetophorales (Chlorophyceae) suffered from limited taxon sampling (six genera with only a single species per genus). To test the monophyly of species-rich genera, and to analyze the phylogenetic relationships among families and genera in the Chaetophorales, we determined nuclear-encoded SSU rDNA sequences from 30 strains of Chaetophorales, performed phylogenetic analyses using various methods, and screened clades for support by unique molecular synapomorphies in the SSU rRNA secondary structure. The Schizomeridaceae and the weakly supported Aphanochaetaceae were recovered as basal lineages. The derived family Chaetophoraceae diverged into two clades: the "Uronema clade" containing unbranched filaments, and a sister clade designated as "branched Chaetophoraceae" comprising Chaetophora, Stigeoclonium, Draparnaldia, Caespitella, and Fritschiella. Although some terminal clades corresponded to genera described (e.g., Caespitella and Draparnaldia), other clades were in conflict with traditional taxonomic designations. Especially, the genera Stigeoclonium and Chaetophora were shown to be polyphyletic. The globose species Chaetophora elegans was unrelated to lobate Chaetophora spp. (e.g., Chaetophora lobata). Since the original description of Chaetophora referred to a lobate thallus organization, the latter clade represented Chaetophora sensu stricto. In consequence, C. lobata was designated as lectotype of Chaetophora. Two Stigeoclonium species, Stigeoclonium farctum Berthold and Stigeoclonium'Longipilus', diverged independently from the type species of Stigeoclonium, Stigeoclonium tenue (C. Agardh) Kütz. These results indicated that some commonly used taxonomic characters are either homoplasious or plesiomorphic and call for a reevaluation of the systematics of the Chaetophorales using novel morphological and molecular approaches.
先前发表的关于毛枝藻目（绿藻纲）的分子系统发育分析存在分类群取样有限的问题（六个属，每个属仅一个物种）。为了检验物种丰富的属的单系性，并分析毛枝藻目各科和属之间的系统发育关系，我们测定了30株毛枝藻目的核编码小亚基核糖体DNA序列，使用多种方法进行了系统发育分析，并通过小亚基核糖体RNA二级结构中的独特分子共衍征筛选分支以获得支持。裂丝藻科和支持度较弱的隐丝藻科被恢复为基部谱系。衍生的毛枝藻科分为两个分支：包含不分枝丝状体的“尾丝藻分支”，以及一个姐妹分支，称为“分枝毛枝藻科”，包括毛枝藻属、鞘藻属、竹枝藻属、集毛藻属和弗里奇藻属。虽然一些末端分支与已描述的属相对应（如集毛藻属和竹枝藻属），但其他分支与传统分类命名不一致。特别是，鞘藻属和毛枝藻属被证明是多系的。球状的秀丽毛枝藻与叶状毛枝藻属物种（如叶状毛枝藻）无关。由于毛枝藻属最初的描述涉及叶状的藻体结构，后一个分支代表狭义的毛枝藻属。因此，叶状毛枝藻被指定为毛枝藻属的模式标本。两种鞘藻属物种，紧密鞘藻和“长柄鞘藻”，与鞘藻属的模式物种纤细鞘藻独立分化。这些结果表明，一些常用的分类特征要么是同塑性的，要么是近祖性的，需要使用新的形态学和分子方法重新评估毛枝藻目的系统学。
