Abstract:
An attempt was made to isolate morphological mutants from wild populations of Drosophila ananassae from two locations close to Colombo in Sri Lanka to estimate the mutation load in these wild population.
Seventeen mutants of spontancous origin have been isolated. From eight recessive mutants, namely, marginal cell cross vein wing (mcv), marginal cell double cross vein wing (mdcv) demi wing (dw), reduced eye (re), brown eye (bw), marginal celless wing (mcl), semi wing (sw) and cut wing (ct) it has been calculated that the heterozygous mutant load in D.ananassae in the wild populations in Sri Lanka is 0.29 per individual. The value is seen to be much lower than the value obtained for D.ananassae in a Pacific Island by Spencer (0.63 per individual). A dominant mutant, Curled wing (Cu), was also obtained from the wild. The mutants hooked leg (hl), net wing (nt), ballooned semi wing (bsw) arose from the culture of curled wing (Cu) and notch wing (n) mutant arose from the culture of marginal cell less wing (mcl). These have not been fully tested. The mutants marginal cell cross vein wing (mcv) marginal cell double cross veins wing (mdcv), demi wing (dw), reduced eye (re), marginal cell less wing (mcl), semi wing (sw), ballooned semi wing (bsw) and Curled wing (Cu) to our knowledge is being reported for the first time. Seven mutants are due to autosomal recessive genes, four are recessive sex linked mutants and only one is dominant autosomal gene.
