4. In a large population of an annual wild pea species, height is controlled by

Question

4. In a large population of an annual wild pea species, height is controlled by a single locus; HH and Hh individuals are tall, while hh individuals are short. Because the local environment is very windy, tall plants tend to get broken and survive to reproduce only half as well as well as do short plants. Mating is random with respect to height and there is no immigration or emigration. In a population of 21,000 (large enough to be considered infinite for the purposed of the Hardy- Weinberg equilibrium and natural selection models; assume this population size remains constant through the generations described in this question) adult pea plants that successfully reproduce after natural selection through differential survival has occurred, there are 7,000 HH individuals, 7,000 Hh individuals, and 7,000 hh individuals 0 ovules) that will unite to make up the next generation? to start the next generation? How many seeds will there be with each genotype? from these seeds and survive to reproduce? How many adults will there be with each population? a) What will be the frequency of the H allele in the gametes (sperm, in pollen, and b) What will be the genotype frequencies of HH, Hh, and hh in the seeds that are formed c) What will be the genotype frequencies of HH, Hh, and hh in the adults that develop d) Over a long period of time, what do you expect to happen to the H and h alleles in this

Explanation / Answer

4a. What will be the frequency of the H allele in the gametes (sperm, in pollen, and ovules) that will unite to make up the next generation?

ANS: The individuals of each type are 7000, therefore, the frequency of allele d would be- 7000 / 21,000 = 1/3 = 0.33

this is the frequency of d^2 so d would be- 0.57

now, H + h = 1

so the frequency of H would be= 0.43

4b. What will be the genotype frequencies of HH, Hh, and hh in the seeds that are formed to start the next generation? How many seeds will there be with each genotype?

ANS: The genotype frequencies of each of the alleles would be as follows:

HH = 0.43 X 0.43 = 0.18

Hh = 0.43 x 0.57 = 0.24

hh = 0.57 x 0.57 = 0.32

therefore in the next generation the seeds would be 32% would be dd, 24% would be Hh and 18% would be HH.

4c. What will be the genotype frequencies of HH, Hh, and hh in the adults that develop from these seeds and survive to reproduce? How many adults will there be with each genotype?

ANS: Since, only half of these tall genotypes survive to reproduce, therefore, hh would remain 32%, but Hh would be half i.e. 12% and HH would be 9%.

4d. Over a long period of time, what do you expect to happen to the H and h alleles in this population? Why?

ANS: Over a long period of time, the alleles of H and h would change very much because the natural selection would favor the h allele and not the H allele. the frequency of allele H would keep on decreasing and the frequency of allele h would keep on increasing.

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