Phylogenetic relationships within the Sphacelariales (Phaeophyceae): rbcL, RUBISCO spacer and morphology
Phylogenetic relationships within the Sphacelariales (Phaeophyceae): rbcL, RUBISCO spacer and morphology
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Sphacelariales（褐藻纲）内的系统发育关系：rbcL、RUBISCO 间隔区和形态
DOI：
10.1017/s0967026202003736
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
W. F. P. van Reine
中科院分区：
文献类型：
--
作者：
S. Draisma;J. Olsen;W. Stam;W. F. P. van Reine
严格意义上的Sphacelariales内的系统发育关系进行了研究，使用分子和形态学的方法。包括20种，代表所有3个科（即枝梗藻科，Sphacelariaceae和Stypocaulaceae）和8个属中的6个。外群包括6个种，分别代表了Syringodermatales、Dictyotales、Choristocarpaceae和Onslowiaceae。测定部分rbcL [1255-1375个核苷酸（nt）]和相邻RUBISCO间隔区（40-842 nt）的DNA序列以评估分子同源性。只有间隔区的3′-端（112 nt位置）对于内群分类群是可重复的。分配均匀性检验表明rbcL和RUBISCO间隔区序列可以组合。然而，单独或与RUBISCO间隔物组合的rbcL的分析给出了相同的结果，仅在支持方面存在轻微差异（自举、折刀、衰减）。在内部群体的基础上，支持率很低。（4）所有其他包括的分类群：（Sphacella subtilissima+ Sphacelaria subgenus）和（Cladostephus spongiosus+ Sphacelaria nana+ Sphacelaria subgenus Battersia+Pseudochaetopteris）。独立的形态学分析（使用23个无序的形态特征）显示高的同源性和几乎完全未解决的树，其中只有亚属的支持。随后将形态特征映射到rbcL树上，以确定诊断或遗传信息特征。变黑响应漂白和存在的次级节被认为是Sphacelariales的基础synapomorphies;存在的繁殖体与一个透镜状的中央顶端细胞定义的adulifera;和严格的acroblastic分支模式和腋生zoidangia定义Stypocaulaceae。其余的角色已经多次获得或失去。这项研究突出了极端形态收敛和/或可塑性的问题。四个选项，包括命名的变化，一个新的界限进行了讨论。得出的结论是，没有一个备选办法会使识别或分类更加明确。
Phylogenetic relationships within the Sphacelariales sensu stricto were investigated using both a molecular and a morphological approach. Twenty species were included, representing all three families (i.e. Cladostephaceae, Sphacelariaceae and Stypocaulaceae) and six of the eight genera. The outgroup consisted of six species representing the Syringodermatales, Dictyotales, Choristocarpaceae and Onslowiaceae. DNA sequences of partial rbcL [1255–1375 nucleotides (nt)] and the adjacent RUBISCO spacer (40–842 nt) were determined in order to assess the molecular phylogeny. Only the 3′-end of the spacer (112 nt positions) was alignable for the ingroup taxa. Partition homogeneity testing showed that rbcL and RUBISCO spacer sequences could be combined. However, analysis of rbcL alone or in combination with the RUBISCO spacer gave the same results with only slight differences in support (bootstrap, jackknife, decay). Support was low at the base of the ingroup. Four basal clades could be discerned: (1) Stypocaulaceae, (2) Sphacelaria radicans, (3) Sphacelaria caespitula and (4) all other included taxa: (Sphacella subtilissima+the Sphacelaria subgenus Propagulifera) and (Cladostephus spongiosus+Sphacelaria nana+the Sphacelaria subgenera Battersia+Pseudochaetopteris). The independent morphological analysis (using 23 unordered morphological characters) revealed high homoplasy and an almost completely unresolved tree in which only the subgenus Propagulifera was supported. The morphological characters were subsequently mapped onto the rbcL tree in order to identify diagnostic or phylogenetically informative characters. Blackening in response to bleach and the presence of secondary segments were found to be basal synapomorphies for the Sphacelariales ; presence of propagules with a lenticular central apical cell defines the Propagulifera; and strict acroblastic branching mode and axillary zoidangia define the Stypocaulaceae. The remaining characters have been gained or lost multiple times. This study highlights the problem of extreme morphological convergence and/or plasticity. Four options for a new circumscription including nomenclatural changes are discussed. It is concluded that none of the options will lead to greater clarity with respect to either identification or classification.