In this lab, our hypothesis was that
the change in allele frequency relies on genetic drift due to random loss and
gain of alleles. We predicted that the change in allele frequency will be
random with no dependence on either color or initial allele frequency.
Table
1. Number of alleles over 10 generations in population A and over 8 generations
in population B.
Reflect the color of
beads
|
Generations
|
|||||||||
Population A
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
Red
|
12
|
10
|
9
|
8
|
7
|
10
|
11
|
12
|
16
|
16
|
Clear
|
15
|
16
|
13
|
11
|
13
|
17
|
20
|
20
|
19
|
22
|
Blue
|
12
|
15
|
18
|
23
|
24
|
15
|
9
|
7
|
7
|
5
|
White
|
11
|
9
|
10
|
8
|
6
|
8
|
10
|
11
|
8
|
7
|
Population B
|
||||||||||
Red
|
13
|
13
|
13
|
13
|
11
|
11
|
7
|
5
|
||
Clear
|
11
|
11
|
6
|
6
|
11
|
11
|
19
|
22
|
||
Blue
|
12
|
14
|
16
|
15
|
15
|
16
|
10
|
9
|
||
White
|
14
|
13
|
15
|
12
|
13
|
12
|
14
|
14
|
||
Figure
1: The data of the number of beads by colors through 10 generations in population
A. Initial numbers were one-half picked randomly from a gene pool.
Table 2. Calculation of chi-squared statistic in population A.
Observed data were initial numbers of alleles and expected data were numbers of
alleles in the 10th generation.
Substrate
|
Observed, O
|
Expected, E
|
O - E
|
(O-E)2/E
|
Red
|
16
|
12
|
4
|
1.33
|
Clear
|
22
|
15
|
7
|
3.27
|
Blue
|
5
|
12
|
7
|
4.08
|
White
|
7
|
11
|
4
|
1.45
|
Total
|
10.13
|
Figure
2: The data of the number of beads by colors through 8 generations in population
B. Initial numbers were the second half from the same gene pool with the second
population.
Table 3. Calculation of chi-squared statistic in population B.
Observed data were initial numbers of alleles and expected data were numbers of
alleles in the 8th generation.
Substrate
|
Observed, O
|
Expected, E
|
O - E
|
(O-E)2/E
|
Red
|
5
|
13
|
8
|
4.9
|
Clear
|
22
|
11
|
11
|
11
|
Blue
|
9
|
12
|
3
|
0.75
|
White
|
14
|
14
|
0
|
0
|
Total
|
16.65
|
Conclusion:
After calculations, two chi-squared results 10.13 and 16.65 are both bigger than a chi squared score of 7.82, which was derived using a p-value of 0.05 and 3 degrees of freedom. There was enough evidence to conclude that there was a significant change in alleles in both populations.
The mechanism that caused the change in allele frequencies was genetic drift. This conclusion is drawn from the randomness of the color of which beads persisted and which ones did not. In population A, the red beads increased in allele frequency while population B resulted in the opposite (decreasing frequency). Also when using a genetic drift simulator, consistent results are not achieved. The simulator produces randomness similar to the change in allele frequencies of both populations A and B of this lab.
Resources used:
Shlichta, G., Hanson, C. & Mcfarland, J. (2017, Winter). Biol&
212 Major Animal Biology Laboratory Manual
student data section AA (2017, Jan. 5) Canvas
No comments:
Post a Comment