How can evolution be measured?
Looking at changed in allele and genotype frequencies in a population over time
Hardy-Weinberg equilibrium principle
The population genetics theorem that states that the frequencies of alleles and genotype in a large sexually reproductive population
- remain constant from generation to generation when acted upon Mendelian processes (segregation and recombination)
-don’t not remain constant from generation to generation when acted upon by evolutionary processes
Remain constant during what?
Mendelian processes - segregation and recombination of alleles
do not remain constant during what?
When acted upon evolutionary processes - mutation, migration, genetic drift, random mating and natural selection
In the hardy-Weinberg model —— does not occur
Evolution does not occur
Allele frequencies
Measure the amount of genetic variation - estimate how common allele are in the whole population
Genotype frequencies
Show how a populations genetics theorem variation is distributed among its members
What does the HW do for science?
Enables us to predict allele and genotype frequencies from one generation to the next in the absence of evolution
What are the conditions required for the HW equilibrium
- no mutations
- no selection among genotypes
- no gene flow (migration)
- population size is infinite
- mating is random
P =
Frequency of the dominate allele
q =
Frequency of the recessive allele
P^2
Frequency of AA ) homozygous dominate individual)
2pq
Frequency of Aa (heterozygous individual)
q^2
Frequency of aa homozygous recessive individuals
Population in nature —- meet the strict conditions necessary to be HW equilibrium
Never, this is why all biological populations evolve
Why then, is this model considered so important for the study of evolution?
1 the equation is useful for predicting genotype frequencies of a population from its allele frequencies
2 allows biologist to evaluate which process are acting on the evolution of a particular population . The specific pattern of deviation from HW equilibrium can help identify the various processes of evolutionary change
