In a 2010 re-survey of the lake, another 500 crayfish were randomly surveyed. Th

Question

In a 2010 re-survey of the lake, another 500 crayfish were randomly surveyed. The survey revealed that the population is now only 9,000 crayfish. Some of the new allele frequencies, which have clearly changed since 1990, are indicated in the table below.

Gene                Allele                        Allele Frequency

CPX                  CPX 0.41

                        cpx    

SWM              SWM                           0.67

                      SWM’                          0.15

                       swm    

MOLT             MOLT 0.27
                     molt

4. Based on this 2010 data, determine the following for both the sample and the total population of the lake.

a. What are the allele frequencies of cpx, swm, and molt?

b. How many crayfish are brown?

c. How many crayfish are cream?

d. What is the genotype frequency of SWM/swm?

e. What is the phenotype frequency of crayfish with sharp-tipped swimmerets?

f. How many of the crayfish in the lake molt repidly?

Explanation / Answer

As we know that the total frequescy of an allele should be 1 in any populaition for any gene. Within this value both the alleles may differ in frequency for each gene and also for each population. Here we found the frequecy of one allele for some genes of Cray fish.

a. The freqeuncy of cpx 0.59. swm 0.18, molt 0.73.

b. As here it is n ot mentioned that which gene is responsible for the coloration, it is difficult to calculate the no of crayfish in different colors. Which allele is dominant and codes for which color is also a vital information for the answers of b and c. Still we can learn about how to calculate no of individuals from the allele frequency. Suppose the resposible gene is cpx and the dominant form CPX codes for the brown color whereas, the recessive form cpx codes for the cream color. p2 + 2pq+ q2 = 1. Here the dominant allele is p and the recessive allele is q.

Now here the frequency of CPX is 0.41 so the genotype frequency will be 0.412 so out of 9000 crayfish 1440, similarly cpx is 0.59 genotype frequency will be 0.592 i.e. 3060, the heterozygous will also be brown and the it s 2pq and the no is 5320.

d. the genotype frequency of SWM/swm is 2*0.67*0.18 = 0.24 .

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.