Population genetics of Drosophila nasuta nasuta, Drosophila nasuta albomicana and their hybrids

Abstract

Interracial hybridization experiments between D. n. nasuta and D. n. albomicana were made. During gametogenesis there was selective elimination of abnormal gametes in F1 females; hence, only normal gametes were produced. F1 males yielded both normal and abnormal gametes. Fertility tests on F2 and backcross progeny showed males are more often sterile than females. The implications of these findings are discussed.

Estimation of population fitness of parental races Drosophila nasuta nasuta and Drosophila nasuta albomicana and of the newly evolved Cytoraces I and II

“…(ii) Egg to adult rate of development: Eggs of approximately the same age ( k 4 h) of these four populations were collected using the modified procedure of Delcour (Ranganath and Krishnamurthy 1974). Eggs were collected on acetic acid -alcohol media and, with sterilized microneedles, transferred to 1 in.…”

“…Drosophila nasuta nasuta (2n = 8) and Drosophila nasuta albomicana (2n = 6) are a pair of morphologically indistinguishable cross-fertile races. These allopatric chromosomal races belong to the nasuta subgroup of the immigrans species group of Drosophila and to date there are no reports of hybridization between these races in nature (Nirmala and Krishnamurthy 1972;Ranganath 1978;Ranganath and Hagele 198 1, 1982;Ramachandra and Ranganath 1986;Ranganath and Ramachandra 1987). Detailed investigations of these races concerning the patterns of meiotic F, chromosome segregation (Ranganath and Krishnamurthy 198 l), location and differentiation of heterochromatin , satellite DNA , major changes in the microchromosomes , location of NORs (Hagele and Ranganath 1983), and their mating preferences have shown the extent of similarities and differences between them.…”

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

“…During the last decade there have been reported of additional collections as well as the results from a variety of laboratory studies since this subgroup was recognized as providing excellent material for the study of speciation in Dro- sophita (Spieth 1969;Kanapi and Wheeler 1970;Krishnamurthy 1973,1974;Ranganath and Krishnamurthy 1976, 1981Lin et at. 1977;Thongmeearkom et at.…”

Evidence for no sexual isolation between Drosophila albomicans and D. nasuta

“…Both F 1 interspecific hybrid males and females are apparently fertile (Kitagawa et al. ), but some of the F 2 hybrid males are sterile (Ranganath and Krishnamurthy ), presumably because they had the XO genotype as a consequence of losing the Y chromosomes during meiosis in their father (Chang and Kung ). An abnormal sex ratio was detected in both interspecific and intraspecific crosses.…”