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Population Genetics. Relative Frequency of an Allele. 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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Relative Frequency of an Allele • 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 • What do you think are some sources of genetic variation? Mutations Natural Selection gene flow genetic drift
A note on sexual reproduction… • 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 • Shuffling cards gives you different hands • It won’t change the number of kings in a deck
Genetic Equilibrium:Hardy-Weinberg Principle • 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 • Random Mating • Large Population • No Immigration/Emigration • No Mutations • No Natural Selection • This means that no phenotype can have a selective advantage over another
Hardy-Weinberg • In reality, no population satisfies the Hardy-Weinberg equilibrium completely • However, in large populations with little migration and little natural selection, it can approximate gene frequencies