Drosophila Melanogaster Experiment Essay

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Drosophila melanogaster were studied to test whether evolution occurred in the population by analyzing the genotype and allele frequencies for 7 weeks. If evolution was occurring, then the aforementioned frequencies would change instead of remaining constant as they would if no evolution was occurring. The hypothesis of this lab is that evolution will occur due to the violation of three Hardy-Weinberg principles. This lab was carried out using 20 flies to start, 5 each of male and females that were homozygous ebony and wild type. New culture vials were made every other week when the flies were scored. On alternate weeks, the adults were transferred to a fly morgue. The results showed that the ebony allele frequency increased and the wild type…show more content…
The ebony allele frequency increased and the wild type allele frequency decreased. The heterozygous genotype frequency remained fairly constant, the homozygous for wild type frequency decreased, and the homozygous for ebony frequency increased. The low probability of the changes in allele and genotype frequencies occurring due to chance for week 3 indicates that evolution is occurring while opposite is true for weeks 5 and 7, where the changes can be attributed to chance, meaning the null hypothesis is true for those weeks. Thus, it can be said that the hypothesis that evolution will occur can be rejected because overall it is likely that the changes in frequencies were due to chance, not evolution. A study at the University of Sheffield regarding competitive mating success revealed that the fact that male ebony flies are partially blind, which reduces their mating success as compared to heterozygous males. Furthermore, the heterozygous wild type flies have an advantage over homozygous wild type flies in that they have a superior courtship song. This study helps to explain why the genotype frequencies in week 7 in order from greatest to least were as follows: +e, ee, ++.
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