Lab #1: Population Genetics by Auryana Ashoori, Tien Pham, Karley Quibilan, and Hannah Zaini
Lab #1: Population Genetics by Auryana Ashoori, Tien Pham, Karley Quibilan, and Hannah Zaini
A. Distribution of Genes in a Population
Hypothesis: The genotype frequency in a population cannot be predicted using Mendelian Genetics.
Null Hypothesis: Genotype frequency in a population can be predicted with Mendelian Genetics ratios.
Prediction: If the population follows Mendelian Genetics, we would expect 12.5 (25%) Homozygous white pairs, 25 (50%) Heterozygous pairs, and 12.5 (25%) Homozygous speckled pairs. If the population does not follow Mendelian Genetics, we will not see these ratios.
Figure 1. Graph showing the genotype ratios of a population based on Mendelian Genetics and an observed population A.
Figure 2. Graph showing the genotype ratios of a population based on Mendelian Genetics
and an observed population B.
and an observed population B.
Conclusion:
In population A, the data supports the hypothesis in that Mendelian Genetics cannot
predict genotype ratios of a population and rejects the null hypothesis.
This is because the chi squared value is beyond the critical value of 5.99, at 9.68,
which means the data does not fall within the expected Mendelian Genetics genotype ratio
of 1:2:1. Looking at Figure 1, the observed data does not correlate with the expected data
which furthers our point. In population B, the data supports the null hypothesis in that
Mendelian Genetics can predict genotype ratios of a population, as you can see in Figure 2
with the observed data being similar to the expected data. The chi squared value is 0.72,
which falls below the critical value of 5.99 and falls within the expected Mendelian Genetics
genotype ratio of 1:2:1.
predict genotype ratios of a population and rejects the null hypothesis.
This is because the chi squared value is beyond the critical value of 5.99, at 9.68,
which means the data does not fall within the expected Mendelian Genetics genotype ratio
of 1:2:1. Looking at Figure 1, the observed data does not correlate with the expected data
which furthers our point. In population B, the data supports the null hypothesis in that
Mendelian Genetics can predict genotype ratios of a population, as you can see in Figure 2
with the observed data being similar to the expected data. The chi squared value is 0.72,
which falls below the critical value of 5.99 and falls within the expected Mendelian Genetics
genotype ratio of 1:2:1.
B. Genetic Drift or Natural Selection
Hypothesis: Due to Genetic Drift or Natural Selection, allele frequencies in a population over
multiple generations will change.
multiple generations will change.
Null Hypothesis: There will be no change in allele frequencies in a population over multiple generations.
Prediction: If there is no Genetic Drift or Natural Selection, then we would expect the frequency of each
allele to remain at about the same (3) from generation 1 to 10. If there are any processes acting on the
population, then the allele frequencies will change over time, modeling evolution.
allele to remain at about the same (3) from generation 1 to 10. If there are any processes acting on the
population, then the allele frequencies will change over time, modeling evolution.
Figure 3. Graph showing the change in allele frequencies of 4 different alleles in Population A over 10 generations.
Figure 4. Graph showing the change in allele frequencies of 4 different alleles in Population B over 10 generations.
Conclusion:
For both populations the data supports the hypothesis in that the frequency of alleles will
change over time due to Natural Selection or Genetic Drift and rejects the null hypothesis.
Figure 3 and 4 shows the fluctuation in bead color every generation which supports our
hypothesis. In addition, the chi squared values, 27 and 18.8, are above the critical value of 7.82,
which rejects the null hypothesis of no change in allele frequency. Population A and B show
genetic drift due to random fluctuation in allele frequencies over time. Figure 3 and 4 shows
that the first and last generation does not contain the same allele frequency and has varied
over time.
change over time due to Natural Selection or Genetic Drift and rejects the null hypothesis.
Figure 3 and 4 shows the fluctuation in bead color every generation which supports our
hypothesis. In addition, the chi squared values, 27 and 18.8, are above the critical value of 7.82,
which rejects the null hypothesis of no change in allele frequency. Population A and B show
genetic drift due to random fluctuation in allele frequencies over time. Figure 3 and 4 shows
that the first and last generation does not contain the same allele frequency and has varied
over time.
Something I noticed about your guys' data is that the data for population A and B in the second part of the lab have very similar results in comparing the first and tenth generations. Both of the white and blue alleles increased, while both of the red and clear alleles decreased. I wonder how long the pattern would remain similar before they started to diverge significantly? And would there be a period of time if we were to separate a real population where both would follow the same evolutionary pattern before speciation took place? The data between my population A and B was drastically different. I wonder if there's some underlying bias that plays a role in selection?
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ReplyDeleteHey, Great work. I find it interesting that for Part A in population A that white beans had an equal population to brown speckled. Perhaps you had a different method of selecting the beans that makes it more equal but, when I did mine, the speckled beans were much bigger than the white which made the white selected less.
Hello guys! To begin, I would like to say that your four different graphs are really clear and well organized. This is really helpfull for me as a viewer, because I don't have to study the graph for several minutes trying to understand what's the point you are trying to make. I could say the same thing about your hypothesis: you are going straight to the point and this is great. However, I wish you guys have discussed the reasons of you null hypothesis's rejection for Part B: what kind of selection happened in order to deviate from the Hardy Wienberg's predictions?
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