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UBC Theses and Dissertations

The duration of life of Drosophila melanogaster in various environments Cohen , Barrie


A series of experiments were conducted to observe the effect of various environments on the duration of life of wild-type Drosophila melanogaster. Natural duration of life curves were prepared for these insects from 10.5 days of age and it was found that the average life expectancy of the males was greater than that of the females. A 10ˉ⁴ M concentration of the mutagen acridine orange in the medium markedly reduced the average life span of Drosophila males and females. The 10ˉ⁵ M concentration reduced the male life expectancy slightly but had no effect on the females. A method utilizing a separatory funnel type population container was developed to test the effect of a chemical stress on Drosophila populations. Some preliminary experiments were performed in order to evaluate the effect of 10ˉ³ M 2, 4-dinitrophenol, a metabolic inhibitor, combined with various food environments on life duration. The sexes differed in their response to these environments and the relative durations of life of the flies were compatible with a priori considerations. From the results a non-linear relationship is suggested between the time of 50% population death and the rate of death. Starvation death curves were compiled for the Drosophila after they were exposed to various conditions which were thought to be representative of the natural environment. Following exposure to various media conditions, female Drosophila under starvation conditions outlived their male counterparts. The difference between the starvation life expectancies of the females and males tended to become greater after the insects had been kept under optimum conditions, due predominantly to an increase in female life duration. Utilizing a combination of a rapid 'quantitized' heat-shock and starvation conditions it was found that only the male starvation life duration was significantly decreased compared with the unshocked starved controls. The female starvation life duration did not appear to be significantly decreased by the heat-shock. Under starvation conditions wholly female populations had a life duration similar to female populations mixed with an equal number of males. Some explanation is given for the results obtained in this thesis and recommendations for further experiments are made.

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