Vestigial and Ebony Drosophila melanogaster experiment Christina Lees Ashley Michels Jordon Maslin Abstract: The purpose of this experiment is to find the expected ratio for the cross vestigial and ebony. To find the outcome of this cross we will be creating cultures for the Drosophila melanogaster and putting males and females into these cultures. In this experiment you will have the D. melanogaster mate to get an F2 generation which you will use to make your dihybrid cross to get your observed ratio. The observed F2 generation of the experimental dihybrid cross ratio ended up being 9:3:3:1, with 276 wild type/wild type, 115 ebony/wild type, 90 vestigial/wild type, and 21 vestigial/ebony. In this experiment the main objective was to learn how to put together Chi2 charts, dihybrid crosses, and putting D.melanogaster cultures together. Introduction: The Drosophila melanogaster, the common fruit fly, has been used in genetics since 1910 for primary research (Genetics Laboratory Manual). The first person to use the D. melanogaster was Thomas Hunt Morgan to show that Mendel's Law works in animals (Genetics Laboratory Manual). The D. melanogaster is used in genetics the flies make it easy to care for and keep because they use so little space and effort. D. melanogaster will be used because they are the model organism for this type of experiments. The D. melanogaster is viability, has a good fecundity, and a longevity character to constitute the life history meaning that these D. melanogaster are able to develop normally, have a reproduction outcome, and their life history is long for them (Michael Rose). The purpose of this experiment is to understand how genetics works. The D. melanogaster will be able to tell us how a trait can be pasted down from one generation to another generation. In this experiment the group got the D. melanogaster which included vestigial and ebony. From the first generation it was observed that the second generation with different traits form the parents. The null hypothesis for this specific cross is 9:3:3:1. This cross should have that ratio because of the amount of traits there are because this will become a dihybrid cross. Methods: In this experiment, each group received a stock vial from the Biological supply company and also three clean empty were used to transfer the D. melanogaster from one vial to another. The clean vial was held above the D. melanogaster to let them fly or crawl up. Once the D. melanogaster were transferred into the clean vial the FlyNap was used to make them sleep. After all the D. melanogaster fell asleep, they are poured onto a note card to count and separate the females and the males under a dissecting microscope. The two other clean vials the were filled with about 10mL of dry medium and an equal amount of tap water was added. The medium was wet but the overall mixture did not have too much fluid. The medium also includes a pinch of yeast along with a plastic mesh. After the females and the males were separated, they were divided into two prepared culture vials, each with an equal amount of each males and females. In my group one vial was filled with six females and six males and in the other vial there were seven females and six males. The two vials are labeled with lab group's name and the description of the cross. These D. melanogaster will mated to make the second generation. The second part of this experiment will be to acquire the second generation. Once the groups get back their vials with their D. melanogaster the group would hold another clean vial above the D. melanogaster again to let them fly or crawl up. When all of their D. melanogaster go into the new vial the group would then use the FlyNap again to make them fall sleep. Once all of the groups D. melanogaster fall asleep the group would pour them out and would count how many D. melanogaster was whichever cross your group would have. After counting all of the D. melanogaster into the two or four groups the groups may place them in the morgue. Results: In this experiment, the F1 generation of Drosophila melanogaster were vestigial/ebony. Once the group put males and females in two different vials, they were sorted by seven males and six females in one vial and six males and six females in the other vial. The next time that the group looked at the D. melanogaster there was the larva and the parents fling around. The group had to use an empty vial to get all the parents out of the other vial with the larva. Once the parents were out of the vial the next class the F2 generation had hatched. Looking at the vial with the F2 generation the group counted all the D. melanogaster and put them into four different groups. The groups were vestigial/ebony, vestigial/wild type, ebony/wild type, and wild type/wild type. In the F2 generation there were 90 vestigial/ebony, 21 vestigial/ebony, 276 wild type/wild type, and 115 ebony/wild type. The punnet square below is of the F2 generation for the vestigial and ebony D. melanogaster. In this punnet square the group ended up with a 9:3:3:1 ratio. F2: vge vge vge+ Female vg+e vg+e+ vge vge vge+ vge vg+e vge vg+e+ vge vge+ vge vge+ vge+ vge+ vg+ e vge+ vg+e+ vge+ Male vg+e vge vg+e vge+ vg+e vg+ e vg+e vg+e+ vg+e vg+e+ vge vg+e+ vge+ vg+e+ vg+e vg+e+ vg+e+ vg+e+ Christina, Ashley, Jordan's Group E+_ Vg+_ eeVg+__ E+__vgvg eevgvg Total Observed 276 115 90 21 502 Expected 282.4 94.1 94.1 31.4 O-E -6 21 -4 -10 (O-E)2 36 441 16 100 (O-E)2/E 0.12 4.69 0.17 3.22 8.2 The D.melanogaster data collected will be similar to predicted ratio of nine wild type/wild type for every three Ebony/wild type for every three vestigial/wild type for every one vestigial/ebony. Given four categories, the degrees of freedom is equal to three. The Chi2 critical value for three degree of freedom at 8.2 level so there is no significant difference. The Chi2 calculated value is 8.2. Therefore, the null hypothesis failed to be rejected. Vinit, Thomas, Shawana's Group E+_ Vg+_ eeVg+__ E+__vgvg eevgvg Total Observed 270 90 119 57 536 Expected 301.5 100.5 100.5 33.5 O-E 31 -10 19 24 (O-E)2 961 100 361 576 (O-E)2/E 3.2 1 3.61 17.4 25.21 The D.melanogaster data collected will be similar to predicted ratio of nine wild type/wild type for every three Ebony/wild type for every three vestigial/wild type for every one vestigial/ebony. Given four categories, the degrees of freedom is equal to three. The Chi2 critical value for three degree of freedom at 25.21 level so there is no significant difference. The Chi2 calculated value is 25.21. Therefore, the null hypothesis was rejected. Both Groups Together E+_ Vg+_ eeVg+__ E+__vgvg eevgvg Total Observed 546 205 209 78 1038 Expected 583.9 194.6 194.6 64.9 O-E 37 11 15 14 (O-E)2 1369 121 225 196 (O-E)2/E 2.35 0.62 1.31 3.06 7.34 The D.melanogaster data collected will be similar to predicted ratio of nine wild type/wild type for every three Ebony/wild type for every three vestigial/wild type for every one vestigial/ebony. Given four categories, the degrees of freedom is equal to three. The Chi2 critical value for three degree of freedom at 7.34 level so there is no significant difference. The Chi2 calculated value is 7.34. Therefore, the null hypothesis failed to be rejected. Discussion: In conclusion, the results that were acquired were what was predicted. The observed F2 generation of the experimental dihybrid cross ratio ended up being 9:3:3:1, with 276 wild type/wild type, 115 ebony/wild type, 90 vestigial/wild type, and 21 vestigial/ebony. The Chi2 results that were acquired from the first group turned out better than the other group. The first Chi2 group's critical value was 8.2 which made the null hypothesis fail to reject. However, the second group's results critical value ended up being 25.21 which was rejected. With both of the groups together the Chi2 critical value turned out to be 7.34 which failed to reject. All this data made this experiment agree with the hypothesis. The data that was obtained relates to what was taught in class and provided an example of how genetics works. In this experiment the groups learned firsthand how genetics can be proven by crossing vestigial/ebony traits. In this experiment with Drosophila melanogaster there was one inconsistence and that was that some of the D. melanogaster flew out of the vial into the classroom. Some strengths in this experiment were acquiring a good amount of D. melanogaster in the F2 generation to obtain the hypothesis ratio. To further this experiment, groups could use their F2 generation to continue to a F3 generation and see what type of ratio that groups could acquire then. Each group can just continue with the generations to see what type of ratios each group would get. Thus, the experiment that was conducted turned out to be what was expected from the ratios and the predictions that were made. References: 1. Rose, Michael R., and Brian Charlesworth. "GENETICS OF LIFE HISTORY IN DROSOPHILA MELANOGASTER. I. SIB ANALYSIS OF ADULT FEMALES." 97.1 (1981): 173-86. Print. 2. Rose, Michael R., and Brian Charlesworth. "GENETICS OF LIFE HISTORY IN DROSOPHZLA MELANOGASTER. 11. EXPLOR-4TORY SELECTION EXPERIMENTS." 97.1 (1981): 187-96. Print. 3. York, Karen, et. al. "Exercise 1: Drosophila melanogaster The Model Animal in Genetics Research." Genetics Laboratory Manual. 2-8. Print.