Transcript 2010: Population Genetics and Hardy-Weinberg Equilibrium

Population
Genetics
Relative Frequency of an Allele
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The number of times an
allele occurs in the gene
pool, given as a percentage
Relative frequency has
nothing to do with dominant
or recessive
The recessive allele can
occur more frequently
Sources of Genetic Variation
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What do you think are some sources of
genetic variation?
A note on sexual reproduction…
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Sexual reproduction can produce many
different phenotypes
Sexual reproduction does NOT change
relative frequency of alleles in a population
Think about shuffling a deck of cards
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Shuffling cards gives you different hands
It won’t change the number of kings in a deck
Genetic Equilibrium:
Hardy-Weinberg Principle
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Allele frequency in a population will
remain constant unless an outside
factor causes those frequencies to
change
When allele frequencies remain
constant, we call this genetic
equilibrium
5 Conditions Needed for Genetic
Equilibrium
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Random Mating
Large Population
No Immigration/Emigration
No Mutations
No Natural Selection
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This means that no phenotype can have a
selective advantage over another
Hardy-Weinberg
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In reality, no population satisfies the HardyWeinberg equilibrium completely
However, in large populations with little
migration and little natural selection, it can
approximate gene frequencies