Selection Models HW Problem

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Spriggy
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Selection Models HW Problem

Post by Spriggy » Thu Dec 10, 2009 4:10 am

I can't seem to figure this out. I've tried to plug it into the equations for advantageous dominant allele, disadvantageous recessive allele. I thought I had it worked out, but my professor said I was using the wrong equations, and he's not available to help. I was using p(pw11 + qw12) + q(pw12 + qw22) = w(mean fitness). And then I'd calculate the allele frequencies. I'm lost tho. Any help or advice would be greatly appreciated. Here's the original question. If you'd like me to elaborate on my attempts more, just ask.

A population of sexually reproducing organisms with non-overlapping generations has two alleles: A and a; p is the frequency of A, q is the frequency of a (p+q=1).
Allele a is recessive and lethal when in homozygous genotype (i.e. fitness of aa is zero). Fitness of heterozygote is the same as that of dominant homozygote (full dominance for fitness).
Assume q=0.01. Calculate allele and genotype frequencies for three successive generations of this population (directional, or purifying, selection mode). Explain why delta p will change with generations. Show your calculations and equations used.

cco2e
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Re: Selection Models HW Problem

Post by cco2e » Thu Dec 10, 2009 9:14 pm

I might be wrong, but I have no idea where you got p(pw11 + qw12) + q(pw12 + qw22) = w(mean fitness).

To calculate gene frequencies, use p^2+2pq+q^2=1.

Since you have q=.o1, p=.99

(.99)^2+2(.99)(.01)+(.o1)^2

p^2 is homozygous dominant frequency

2pq is the heterozygous frequency

q^2 is homozygous recessive frequency

I haven't taken genetics in a long time, and someone correct me if I am wrong.

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