Allele Frequencies
Allele Frequencies in Populations: Hardy-Weinberg Law
Assumptions Already Made (Can’t Control)
1) Population Size
2) Mutation
3) Natural Selection
4) Immigration/emmigration
5) Non-random mate choice
Can Control
1) Population Size
2) Natural Selection
Control Variable
Left side
Experimental Variable
Right Side
Comparisons are most meaningful when there is only ONE difference between populations
For this experiment only the population size should be different and everything else should be the same.
Always make sure the Initial Genotype Frequencies and Natural Selection Genotype Viability are the same values for all Genotypes.
To determine the “a” allele
1-“A” allele
To determine the “A” allele
1-“a” allele
The population that is closest to being In the Hardy-Weinberg equilibrium experiment is the control because the population is larger.
Effect of Natural Selection Genotype and Allele Frequencies
We want to compare the results when the Natural Selection Genotype Viabilities are different.
“AA” and “Aa” mosquitoes are resistant to DDT.
This is a high Natural Selection Genotype Viability.
The “aa” mosquitoes have a low viability; meaning they are selected against by the DDT environmental factor.
The result is
AA is exponentially growing
Aa and aa are exponentially decaying
1) This is because A is the dominant Allele and “a” is affected so it will decrease and with less aa and Aa then there is less competition so AA will increase
The frequency of the “a” allele will decay to almost zero for Aa, but it will never die because Aa will survive because of the “A” allele but the aa genotype will die.
NOTES
Each gene carries particular alleles.
We simplify by ignoring all but a single pair of alleles from each organism.
Genotype Frequency- the fraction of a population with a particular genotype
Allele Frequency- The fraction of a particular allele in the population’s gene pool
Hardy-Weinberg Law- States that in the absence of
Assumptions Already Made (Can’t Control)
1) Population Size
2) Mutation
3) Natural Selection
4) Immigration/emmigration
5) Non-random mate choice
Can Control
1) Population Size
2) Natural Selection
Control Variable
Left side
Experimental Variable
Right Side
Comparisons are most meaningful when there is only ONE difference between populations
For this experiment only the population size should be different and everything else should be the same.
Always make sure the Initial Genotype Frequencies and Natural Selection Genotype Viability are the same values for all Genotypes.
To determine the “a” allele
1-“A” allele
To determine the “A” allele
1-“a” allele
The population that is closest to being In the Hardy-Weinberg equilibrium experiment is the control because the population is larger.
Effect of Natural Selection Genotype and Allele Frequencies
We want to compare the results when the Natural Selection Genotype Viabilities are different.
“AA” and “Aa” mosquitoes are resistant to DDT.
This is a high Natural Selection Genotype Viability.
The “aa” mosquitoes have a low viability; meaning they are selected against by the DDT environmental factor.
The result is
AA is exponentially growing
Aa and aa are exponentially decaying
1) This is because A is the dominant Allele and “a” is affected so it will decrease and with less aa and Aa then there is less competition so AA will increase
The frequency of the “a” allele will decay to almost zero for Aa, but it will never die because Aa will survive because of the “A” allele but the aa genotype will die.
NOTES
Each gene carries particular alleles.
We simplify by ignoring all but a single pair of alleles from each organism.
Genotype Frequency- the fraction of a population with a particular genotype
Allele Frequency- The fraction of a particular allele in the population’s gene pool
Hardy-Weinberg Law- States that in the absence of