Biochemical phylogeny of seven Indian species of the montium subgroup of Drosophila

Abstract

Seven species of the montium subgroup of Drosophila found in South India were analysed with polyacrylamide disc electrophoresis. Eleven loci coding for enzymes were surveyed. The genetic distances between species have been measured. The dendrogram revealed three clusters. The first cluster includes D. nagarholensis, D. agumbensis, D. jambulina and D. kikkawai; the second group consists of D. truncata and D. anomelani; while D. mysorensis was the only species of the third group.

Localization and Characterization of Heterochromatin among Four Species of the Montium Subgroup of Drosophila

“…Most species of the montium subgroup show diversity in having different dot chromosomes. Dot chromosomes of D. jambulina are seen as small metacentric (Shyamala andRanganath 1994, Suma andRanganath 1997) in contrast to the earlier reports of Singh and Gupta (1980) and Baimai (1980) identified as large submetacentric dot in the strains studied by them. Baimai et al (1983) identified the karyotypic variation in D. meridionalis due to variant forms of the micro-chromosomes.…”

“…Of the two pairs, the first pair (M1) is longer than the second pair (M2) and their relative length ranges from 281 to 342, while it is 231 to 305 for the second pair (Table 1) The species under study have shown high degree of disparity in the quantity and the distribution of heterochromatin within their genome (Fig. 6) The heterochromatin is believed to have played a significant role in chromosomal evolution in higher organisms (Baimai 1969, Gatti et al 1976, Holmquist 1975, Pathak et al 1973, Yunis and Yasminich 1971, Shyamala and Ranganath 1994, Suma and Ranganath 1997. The amount and position of the heterochromatin influence various attributes of the cell functions like selective advantage (Halfer 1978, Halfer et al 1980) and occurrence of inversions (Baimai 1977).…”

“…In D. kikkawai there are 4 and 9 types of the Y-and the 4th chromosomes, respectively, occurring in wild populations. Shyamala and Ranganath (1994) have reported nearly 6 types of Y-chromosome among eight species are due to heterochromatin and/or pericentric inversions. Most species of the montium subgroup show diversity in having different dot chromosomes.…”

“…Whereas D. anomelani neither resembles any of the species under investigation both morphologically and karyotypically, it can be surmised that the dot and the sex chromosome together in combination can be used as marker to differentiate the karyotype of one species from the other. Phylogenetically it is argued that large dot chromosomes are a recent origin, while the small dot chromosomes with less heterochromatin as ancestral one (Shyamala and Ranganath 1994, Hágele and Ranganath 1982, Baimai et al 1983. On the basis of this it can be said that D. truncata and D. agumbensis with large 4th chromosomes may represent evolutionarily recent species, while D. anomelani and D. cauverii are relatively older forms.…”

“…The wide distribution of subgroup combined with many unique features of individual species, together with wealth of species diversification within subgroup made it an attractive system. The members of this group of Drosophila are highly heterogeneous morphologically (Bock and Wheeler 1972) and karyotypically (Baimai 1980, 1998, Shyamala and Ranganath 1994, Suma and Ranganath 1997. Not more than fifty species of the montium subgroup are subjected to karyotypic analysis (Table 2).…”