Shultz J W, Regier J C
Department of Entomology, University of Maryland, College Park 20742, USA.
Proc Biol Sci. 2000 May 22;267(1447):1011-9. doi: 10.1098/rspb.2000.1104.
Recent phylogenetic analyses using molecular data suggest that hexapods are more closely related to crustaceans than to myriapods, a result that conflicts with long-held morphology-based hypotheses. Here we contribute additional information to this debate by conducting phylogenetic analyses on two nuclear protein-encoding genes, elongation factor-1 alpha (EF-1 alpha) and the largest subunit of RNA polymerase II (Pol II), from an extensive sample of arthropod taxa. Results were obtained from two data sets. One data set comprised 1092 nucleotides (364 amino acids) of EF-1 alpha and 372 nucleotides (124 amino acids) of Pol II from 30 arthropods and three lobopods. The other data set contained the same EF-1 alpha fragment and an expanded 1038-nucleotide (346-amino-acid) sample of Pol II from 17 arthropod taxa. Results from maximum-parsimony and maximum-likelihood analyses strongly supported the existence of a Crustacea + Hexapoda clade (Pancrustacea) over a Myriapoda + Hexapoda clade (Atelocerata). The apparent incompatibility between the molecule-based Pancrustacea hypothesis and morphology-based Atelocerata hypothesis is discussed.
近期利用分子数据进行的系统发育分析表明，六足动物与甲壳类动物的亲缘关系比与多足动物更近，这一结果与长期以来基于形态学的假说相冲突。在此，我们通过对来自广泛节肢动物类群样本的两个核蛋白编码基因——延伸因子-1α（EF-1α）和RNA聚合酶II（Pol II）的最大亚基进行系统发育分析，为这场争论提供了更多信息。结果来自两个数据集。一个数据集包含来自30种节肢动物和3种叶足动物的1092个核苷酸（364个氨基酸）的EF-1α和372个核苷酸（124个氨基酸）的Pol II。另一个数据集包含相同的EF-1α片段以及来自17种节肢动物类群的1038个核苷酸（346个氨基酸）的扩展后的Pol II样本。最大简约法和最大似然法分析的结果有力地支持了甲壳纲 + 六足亚纲分支（泛甲壳动物）的存在，而非多足亚纲 + 六足亚纲分支（无角类）。文中讨论了基于分子的泛甲壳动物假说与基于形态学的无角类假说之间明显的不相容性。
