Genetic studies of the Drosophila nasuta subgroup, with notes on distribution and morphology.

Abstract

The evolutionary genetic studies of more than ten species or subspecies belonging to the D. nasuta subgroup lead the following conclusions :Morphological differentiation has been observed qualitatively as well as quantitatively, but closely related species could not be identified by means of the techniques of external morphology.By Judging from the allozyme analyses, the local populations of D. nasuta were genetically similar in two Esterase loci. The Chiangmai population was differentiated from other allopatric populations of D. sulfurigaster albostrigata. The pattern of the speciation process in the D. nasuta subgroup was discussed.

Metaphase chromosome configuration of the immigrans species group of Drosophila.

“…And further, Matsuzaki and Kitagawa (1982) reported strong commonality in the banding patterns in the salivary gland chromosomes of the two species. D. nasuta has dispersed further to India, Sri Lanka, Seychelles, Mauritius, Reunion, Madagascar and the southern countries of Africa without changing karyotype (Wakahama and Kitagawa 1972;Kitagawa et al 1982) .…”

“…Southern 1964). Judging from the geographical distribution of the species of the immigrans group, especially those of the D. nasuta subgroup, it appears that the origin of the immigrans species group was in Borneo, southeast Asia, and that it has since dispersed to Hawaii and westward to Africa, with further speciation along the way (Wilson et al 1969;Throckmorton 1975;Kitagawa et al 1982). Among them, only D. immigrans has developed into a cosmopolitan species, distributed all over the world.…”

Incipient reproductive isolation between Drosophila nasuta and Drosophila albomicans

“…Members of the D nasuta subgroup are widely distributed from the Pacific Ocean to Africa, through South-east Asia and the Indian Oceans areas (Kitagawa et al, 1982). This subgroup is comparable to the widlistoni species group as subjects for the study of speciation mechanisms.…”

Concentration of chromosomal aberrations on chromosome 3 of Drosophila nasuta

“…The species which show the last category of pattern include D. kohkoa (Mather & Thongmeearkom, 1973), D. nebulosa (Pavan, 1946), D. tetracha eta (Angus, 1968), D. athabasca (Novitski, 1946), D. melanica (Ward, 1952), D. pseudoobscura and D. persimilis (Dobzhansky, 1944), D. guaramunu (Salzano, 1954), D. bocainensis (Carson, 1954), D. paramelanica and D. euronotus (Stalker, 1960(Stalker, , 1964, and D. jambulina (Singh & Gupta, 1980). Drosophila nasuta is a member of the immigrans species group of the subgenus Drosophila and is distributed in several countries of south-east Asia and Africa (Kitagawa et al, 1982 …”