Interaction between selection and genetic drift in laboratory populations of Drosophila bipectinata

To study the effect of selection and random genetic drift in laboratory populations of D. bipectinata, cut wing mutant and wild type stocks were crossed in several bottles. All the lines were maintained for several generations and in each generation the number of wild type and mutant flies was scored. Based on the number of two types of males, the frequency of cut gene and its normal allele was calculated for different bottles since ct is a sex-linked mutation and males are hemizygous. Interestingly, the cut gene was quickly eliminated in all the populations which is due to selection affecting fitness of two types of flies. However, there was considerable fluctuation in gene frequency among different populations and also there was increase in the cut gene frequency in certain generations as compared to previous generation which is caused due to effect of genetic drift which operates in small populations.