Hundred years of research on Drosophila ananassae: a species characterized by a number of unusual genetic features, including incidences of spontaneous male recombination, hypermutability, bacterial association et al.
摘要
Genus Drosophila is characterized by high level of species diversity and contains more than 1500 species at global level. Drosophila melanogaster has been considered as a very good model species which has been extensively used in different areas of biology such as genetics, evolution, population genetics, behavior, ecology, and molecular biology since the time of T. H. Morgan in 1909 who used this species in genetic studies for the first time. A number of other species apart from Drosophila melanogaster, have also been used in various kinds of studies. D. ananassae is noteworthy among these species because it possesses several unusual genetic features which make it to stand distinct in the genus Drosophila. It is of common occurrence in India. In 1930s geneticists from Japan had already indicated that it is a genetically unique species. Doleschall described D. ananassae for the first time in 1858 from Ambon Island, Indonesia. In 1916, Sturtevant described D. caribbea and reported an autosomal recessive mutation, curved wing (cv) in 1921. However, D. caribbea was proved to be identical to D. ananassae by Kikkawa in 1935. Thus the actual genetical work on D. ananassae was initiated in 1921. During this period of about 100 years, D. ananassae has been extensively used for different kinds of studies in genetics, evolution, population genetics, behavior, ecology, genome sequencing, molecular biology etc. by researchers from Japan, India, United States, Germany and France. The results of these studies have clearly revealed that D. ananassae stands distinct in the whole of genus Drosophila as it possesses several unique genetic features such as spontaneous male recombination which is meiotic in origin, high mutability, presence of spontaneous genetic mosaic caused due to mitotic recombination, presence of a large number of translocations and pericentric inversions, absence of genetic coadaptation, and its association with bacteria Wolbachia. Further, speciation studies revealed the discovery of a new species D. pallidosa which is sibling to D. ananassae and both these species occur sympatrically in natural populations of Samoa and Fijji Islands and remain reproductively isolated by ethological isolation. In this review, the researches carried out on this genetically unique species during the last 100 years are briefly described giving more emphasis on its unique genetic features.