Fruit Fly Experiment: Conclusion.

Topics: Sex linkage, Gene, Chromosome Pages: 7 (2191 words) Published: September 9, 2005
10. Errors and Redesign.

Throughout this experiment a number of random and procedural errors were apparent; these errors could have affected the results of the experiment in a number of ways. One experimental error that occurred during the experiment was that some flies became stuck in the food source and died. The main cause of this was the fact that the fly vials were stood up (vertically) before the flies had fully recovered from the anaesthetic. This could be overcome in future experiments by ensuring that the vials are kept horizontal until all of the flies fully recover from the anaesthetic.

One possible error that may have occurred was that some of the adult flies may have accidentally been left in the vials with their offspring, which would have affected the results due to the fact that these flies could have bred with their offspring. This could be overcome in further experiments by ensuring that all adult flies were either removed from the vial or pushed into the food source inside the vial.

It is also possible that some of the maggots and pupa in the vials were killed when the adult flies were anaesthetised. This would have reduced the total number of offspring from each generation ultimately lowering the accuracy of the experiment. This could be prevented in further experiments by anaesthetising and removing the flies faster to lower the amount of time the offspring were exposed to the CO2 gas or by using a less harmful anaesthetising agent.

It is possible that there were mathematical or calculation errors made during the experiment (for example when the fly totals were being tallied). Such errors could be overcome by being more thorough when counting flies and doing calculations, and by double checking calculations.

The sample size of this experiment was quite small; this may have affected the accuracy of the experiment, preventing the hypothesis from being tested properly. This could be overcome in future experiments by breeding more flies and performing multiple trials.

The virginity of the flies used in this experiment was guaranteed. However, it is possible, that the female flies were not virgins and had mated with other flies previously. Female Drosophila flies have seminal receptacles that collect sperm, which is used to fertilise all of the eggs that they have in their lifetime. This means that all of a female fly's offspring could be from a single male making all offspring from a non-virgin female potential "errors" (This is important as a single female fly can lay hundreds of eggs in her lifetime). This would affect the results obtained by both the F1 and F2 generations. It is important to note that no flies with phenotypes other than those predicted were observed. This could be prevented in future experiments by checking the female fly vial thoroughly for eggs, larva and pupa before placing the male flies with them, as this would help ascertain wether the females were truly virgins.

Inaccurate identification of flies may have cause the validity of the experiment to be diminished. One of the main reasons why identification errors may have taken place is that flies with lozenge eyes were hard to identify and required the use of a stereo microscope. When the microscope was not properly in focus gridded flies could easily be mistaken for lozenge flies. Another major source of identification error may have been due to immature males and females as these could easily be confused. In this case the use of a stereo microscope was needed in order to look for the distinct sex combs on the male flies. As this experiment was performed in a group in which a number of individuals sorted the flies the results may have varied from what a single individual would get if they had sorted and counted all of the flies themselves. In future the flies could be double checked by a specific group member in order to standardise the results.

Drosophila melanogaster rely heavily on their sense of sight,...

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Manning, G. (2005). Introduction to Drosophila. [Online] Available: [August 20, 2005]
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