Bio 113P Lab 4: Effects of Wolbachia Infection on the Offspring Sex Ratio of Nasonia, vitripennis

2 this rati feminization and possible male killing

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Unformatted text preview: with the opposite cross, Male B and Female A, we see the opposite results, wherein the largest brood also has the lowest male ratio at 10.2%. This rati feminization and possible male killing occurred had it solely male killing, the brood size would have been significantly smaller. Finally, comparing the homogenous BxB and AxA crosses, the BxB cross had a higher male percentage than the AxA cross, which insinuates that if they were otherwise identical, the A individuals had some factor inducing a larger female percentage; also, looking at the brood sizes for both, it is also clear that there was a significantly reduced brood size for the AxA cross. Together, both these factors strongly suggest that the AxA cross had involved male killing, which would induce both effects, and together with the suspected cytoplasmic incompatibility in the Male A and Female B cross, the data seems to suggest that the individuals of Strain A are infected with Wolba chi a , while those from Strain B are uninfected. Looking at the overall combined numbers, the patterns described become even more clearly visible, with the final evidence coming from the chi-squared analysis. For a difference between the males and females to be significant that is, for the difference to be due to a certain cause, and not just due to coincidence the p value obtained from the analysis must be at least lower than the pre-determined value of R=.05, corresponding to at least a 95% confidence that this is the case. When one looks at how immensely diminutive the p value is in this case, one clearly sees that there is absolutely no chance that this difference between males and females was a fluke indeed, had one originally settled even on a 99% confidence level, and its corresponding R of .01, as the minimum, the results still would have proven valid. This means that the former analysis of the identities of the two strains holds true, since the witnessed differences must have been due to a particular cause, and could not have been fate. Viewing the results of the gel electrophoresis in Figure 2, it becomes evident that the positive control and Strain A both have a second line in common in addition to the main line seen across both DNA-positive controls and strains. The common line correlates to the mitochondrial marker used to confirm that the DNA used was of quality and that the line ran as it should have; the second line correlates to the Wolb a chi a gene marker, as shown by its presence in the positive control, and its absence in the negative control. Thus, its presence in A, but not B, shows that Strain A is infected, and Strain B is uninfected, confirming the prior analysis....
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This document was uploaded on 03/27/2014 for the course BIO 235 at Rochester.

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