The effect of light wavelength on phototactic response in Drosophila melanogaster wild-type and ort1 mutant

Alana Garcia, Ravleen Khurana, Cheryl Liu, Allan Zhu

Abstract


Different spectral wavelengths of light exist in our natural environment that can influence an organism’s behaviour. Some organisms may show a preference for different areas with certain wavelengths while others may completely avoid such regions. We were interested in the phototactic response to certain spectral wavelengths of light, in both the wild-type and ort1 mutant of Drosophila melanogaster. We performed two separate experiments for the wild-type and mutant strains, using green, red, and blue acetate filters at spectral wavelengths of 500, 680, and 410 nm, respectively. We constructed a setup with four t-tubes and measured the time spent by an organism in each of the three regions, in order to test if spectral wavelength preference was present. We found that for both the wild-type and mutant strains there was a significant difference between the percentages of time spent in each of the three different colour regions. For the wild-type strain, we found that the mean percentage of time spent in the green was the highest, followed by red. We found that the blue region had the lowest percentage of time, indicating the lowest preference. For the mutant strain, we found that the highest mean percentage of time was in the green region, followed by blue, and then red. We used the Kruskal-Wallis one way analysis of variance with an alpha p-value of 0.05 and found the wild-type had a p-value of 0.0226 and the mutant had a p-value of 0.028; therefore, we rejected the null hypothesis and found support for our alternate hypothesis; there is an effect of spectral wavelength on phototactic response in wild-type and mutant D. melanogaster.

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