There is no six-legged starfish in existence. Fixation may be to blame. Fixation is a condition in which there is only one allele in the population and the other allele is extinct.
Given that in total 26 starfish are normal and 1 has 6 legs.
Genotypic frequency of 6 legs is 1/27 =0.037
Genotypic frequency is always 1 and is given by p2 +2pq +q2 =1
Allelic frequency = p+q = 1
So,
Frequency of p = 1-0.19 = 0.81
After 2 years:
Chi-square value
Observed Expected O-E (O-E)2 (O-E)2/E
5 leg 0.81 0.65 0.16 0.0256 0.039385
6 leg 0.19 0.35 -0.16 0.0256 0.073143
0.112527
So Chi-square - value is 0.112527
Genotypic frequency of 6 legs is 4/31 =0.129
P =1-0.35= 0.65
So new allelic frequency for 6 legs is 0.35.
New allelic frequency for 5 legs is 0.65.
This random change of allelic frequency is called as genetic drift.
Here is another question with an answer similar to this about genetic drift: https://brainly.com/question/12086252
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Question correction:
On your Spring Break in Mexico, you take a break to count the starfish in a tidal pool. You notice that there is a rare recessive trait that causes the starfish to have 6 legs instead of 5. Of the 27 starfish you can find, only 1 has 6 legs. What are the allele frequencies for this population? Two years later, you return to the same beach and count the starfish again. This time you find 4 starfish out of 31 that have 6 legs. Are the genotype frequencies the same as two years earlier? Test using Chi square. If it is not, calculate the new allele frequencies. Given that the current mutation rate is O and that there is no natural selection acting on these starfish, what is this random change in allele frequency called?)
Seven years later, you come back to the beach. This time you can find no starfish with 6 legs. Given the most recent allele frequencies you know, is this what you would expect? (What is the complete loss of a allele called?)
