ENVIRONMENTAL STRESS AND ITS EFFECTS ON MUTATION RATES IN DROSOPHILA MELANOGASTER
Abstract (Summary)The role of new mutations in the evolution of adaptation remains controversial. It is generally believed that the rate of new mutations is too low to confer an immediate selective advantage. Evolution is thought to occur predominantly through selection acting upon the standing genetic variation of an organisms genome. In bacteria it has been shown that stress may cause the activation of mutator genes that increase the genomic-wide mutation rate. This increase in mutation rate is then selected against when the selective pressures from the stressor are alleviated. The hypothesis that eukaryotic organisms may also be able to modulate their mutation rate in response to environmental stress could explain many aspects of evolution (e.g., the rapid evolution of species during periods of stress followed by stasis in stable environments). We conducted three experiments to test the hypothesis that different environmental stressors would increase either the lethal or the deleterious mutation rate in Drosophila melanogaster. The first experiment examined the effect of size on the rate of lethal mutations in wild-caught flies. The remaining two experiments tested the role of vibration as well as interspecific crowding on both the lethal and deleterious mutation rate. Our results showed a positive correlation between interspecific crowding and the deleterious mutation rate. Vibration was correlated with an increase in the lethal mutation rate, and we found a marginally significant correlation between crowding and the lethal mutation rate. These results are discussed along with their implications for both evolution and conservation.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:mutation evolution drosophila stress
Date of Publication:01/01/2005