Nagaraju J, Ranganath H A
Drosophila Stock Centre, Department of Studies in Zoology, University of Mysore, Manasagangotri, Mysore 570 006, India.
Genes Genet Syst. 2004 Oct;79(5):293-9. doi: 10.1266/ggs.79.293.
The nasuta subgroup is a cluster of morphologically almost similar forms with a wide range of geographic distribution. During the last three decades nature of inter-relationship among the members has been investigated at different levels of organization. The phylogenetic relationships of the members of the nasuta subgroup of the immigrans species group of Drosophila was made by employing Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeats-PCR (ISSR-PCR) polymorphisms, mitochondrial 12S rRNA, 16S rRNA and Cytochrome C Oxidase subunit I (CoI) gene sequences. The phylogenetic tree generated by RAPD analysis is in nearly complete congruence with the classification based on morphophenotypic characters. The 12S and 16S rRNA genes were highly conserved across the nasuta subgroup and revealed only 3 and 4 variable sites respectively, of which only one site was informative. The CoI gene, on the other hand, revealed 57 variable sites of which 25 sites were informative. All the three species of orbital sheen complex were included in a major cluster in the phylogenetic trees derived from mitochondrial gene sequence data consistent with the morphophenotypic classification. The CoI analysis placed two species of frontal sheen complex, D. n. nasuta and D. n. albomicans in two different clades and this is inconsistent with morphological classification. The molecular clock suggested that divergence between the kohkoa complex and the albomicans complex occurred approximately 2.2 MYA, indicating recent evolution of the nasuta subgroup. The higher transition bias in the mitochondrial genes reported in the present study also suggested recent evolution of the nasuta subgroup.
纳苏塔亚组是一群形态上几乎相似的类型，具有广泛的地理分布。在过去三十年里，已经在不同组织水平上研究了该亚组成员之间相互关系的性质。通过使用随机扩增多态性DNA（RAPD）、简单序列重复区间PCR（ISSR-PCR）多态性、线粒体12S rRNA、16S rRNA和细胞色素C氧化酶亚基I（CoI）基因序列，构建了果蝇移民种组纳苏塔亚组成员的系统发育关系。RAPD分析生成的系统发育树与基于形态表型特征的分类几乎完全一致。12S和16S rRNA基因在纳苏塔亚组中高度保守，分别仅显示3个和4个可变位点，其中只有一个位点是有信息的。另一方面，CoI基因显示有57个可变位点，其中25个位点是有信息的。在基于线粒体基因序列数据推导的系统发育树中，眼眶光泽复合体的所有三个物种都包含在一个主要类群中，这与形态表型分类一致。CoI分析将额部光泽复合体的两个物种，即纳苏塔果蝇和白腹黑果蝇置于两个不同的进化枝中，这与形态学分类不一致。分子钟表明，科霍阿复合体和白腹黑复合体之间的分歧大约发生在220万年前，表明纳苏塔亚组是近期进化而来的。本研究报道的线粒体基因中较高的转换偏差也表明纳苏塔亚组是近期进化而来的。
