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珠母贝属(Pinctada)的一些种类是生产海水珍珠的重要母贝,个别种类已濒临灭绝。本文利用核糖体DNA内部转录间隔区1(ITS1)和2(ITS2)序列对珠母贝属常见种类的系统发育和分类地位进行了分析。结果表明:ITS1长410–482bp,其中Pinctadamaxima最长,P.fucata,P.fucatamartensii,P.imbricata和P.nigra最短。ITS2长210–249bp,其中P.albina和P.nigra最长,P.maxima和P.margaritifera最短。碱基替换的同质性检测发现,P.maxima、P.margaritifera和P.chemnitzi的碱基替换格局存在显著性差异,前二者的GC含量显著高于其他种,在进化上可能比较原始;而P.chemnitzi可能发生过染色体重排事件,可能是新近形成的种。系统发育分析表明,所研究的种类可分成3个类群:类群I包含P.fucata、P.fucatamartensii和P.imbricata;类群II包含P.albina、P.nigra、P.chemnitzi和P.radiata;类群III包含P.maxima和P.margaritifera。在类群I中,我国的P.fucata、日本的P.fucatamartensii和澳大利亚的P.imbricata的种间遗传分化不明显,可能为同种,根据命名优先原则应以P.imbricata命名该种为宜。类群II中P.albina和P.nigra可能是两个亚种,而GenBank中的P.radiata(AY144603)可能是P.chemnitzi的误定。类群III(P.maxima和P.margaritifera)分化较早,与碱基替换格局的检测结果相符。
Some species of Pinctada are important mothers producing seawater pearls and individual species are on the verge of extinction. In this study, the phylogenetic and taxonomic status of common species of Ophiopogon japonicus was analyzed using the internal ITS1 and ITS2 sequences of ribosomal DNA. The results showed that ITS1 was 410-482 bp in length, of which Pinctadamaxima was the longest, P.fucata, P.fucatamartensii, P.imbricata and P.nigra were the shortest. ITS2 was 210-249bp in length, of which P.albina and P.nigra were the longest, P.maxima and P.margaritifera were the shortest. The homogeneity of base substitution showed that there was a significant difference in the base substitution pattern between P. maxima, P. margaritifera and P.chemnitzi. The GC content of the two was significantly higher than that of the other species, which may be evolutionarily primitive. P.chemnitzi may have had a chromosomal rearrangement event, probably a newly formed species. Phylogenetic analysis showed that the studied species could be divided into three groups: Group I consisted of P.fucata, P.fucatamartensii and P.imbricata; Group II comprised P.albina, P.nigra, P.chemnitzi and P.radiata; III contains P. maxima and P. margaritifera. In group I, the genetic differentiation between P.fucata in China, P.fucatamartensii in Japan and P.imbricata in Australia is not obvious, may be of the same species, and should be named P.imbricata according to the nomenclature principle. P.albina and P.nigra may be two subspecies in group II, while P. radiata (AY144603) in GenBank may be a false positive for P.chemnitzi. Group III (P. maxima and P. margaritifera) differentiated earlier, consistent with the results of the base replacement pattern.