H.B Shaffer studied the frequencies of alleles for a gene that codes for the enz

Question

H.B Shaffer studied the frequencies of alleles for a gene that codes for the enzyme Alcohol Dehydrogenase (Adh) in the turtle Emydura macquarii, living in ponds near Canberra, Australia. There are 3 alleles for the Adh gene, abbreviated A, B, & C. Shaffer found the following results:

a) Calculate the Allele frequencies for A, B, & C in this population.
b) How many Degrees of Freedom are there in this population? What is the Critical Value? Is this population in HWE, why or why not? Is this population evolving, why or why not?

Explanation / Answer

Compute the frequencies of each allele ie A,B and C:

A:(2*219+69+119)/(2*500)=0.626

B:(2*36+69+2)(2*500)=0.143

C: (2*55 +119+2)(2*500)=0.231

The expected number of individual that would have each genotype if population were at Hardy Wienberg euilibrium,

AA:(0.626)(0.626)500=195.938

AB:(0.626)(0.143)500=44.759

AC:(0.626)(0.231)500=72.303

BB:(0.143)(0.143)500=10.2245

BC:(0.143)(0.231)500=16.5165

CC:(0.231)(0.231)500=26.6805

In Hardy-Wienbery chi-square analysis the number of deree of freedom is equal to number of genotype minus number of alleles. In this case 6-3=3

in general if the number of alleles is n, then the number of genetypes is n(n+1)/2.Thus the numbr of degree of freedom is n(n-1)/2 here n=3

so d.f =3(2)/2=3

so, degree of freedom =3

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