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How do we know if a population is evolving?. When is a population not evolving? / How do we know if a gene pool has changed? / The Hardy-Weinberg Principle.

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Presentation on theme: "How do we know if a population is evolving?. When is a population not evolving? / How do we know if a gene pool has changed? / The Hardy-Weinberg Principle."— Presentation transcript:

1 How do we know if a population is evolving?

2 When is a population not evolving? / How do we know if a gene pool has changed? / The Hardy-Weinberg Principle can help answer these questions. / How do we know if a gene pool has changed? / The Hardy-Weinberg Principle can help answer these questions.

3 The Hardy-Weinberg Principle states: / Genetic equilibrium will be reached if the frequency of alleles remains stable generation after generation. / Genetic equilibrium = no evolution occurring. / Genetic equilibrium will be reached if the frequency of alleles remains stable generation after generation. / Genetic equilibrium = no evolution occurring.

4 Hardy-Weinberg Principle / Conditions necessary for genetic equilibrium are: 1. No mutation occurs 2. Immigration and emigration do not occur (population is isolated from other populations) - no gene flow. 3. Population is very large 4. Mating is totally random 5. All individuals survive and reproduce equally (no natural selection) / Conditions necessary for genetic equilibrium are: 1. No mutation occurs 2. Immigration and emigration do not occur (population is isolated from other populations) - no gene flow. 3. Population is very large 4. Mating is totally random 5. All individuals survive and reproduce equally (no natural selection)

5 Hardy-Weinberg Principle / It is virtually impossible to meet these conditions. / Allelic frequencies do change in populations, therefore evolution occurs. / The main application of this principle is calculating allele and genotype frequencies in a population. / It is virtually impossible to meet these conditions. / Allelic frequencies do change in populations, therefore evolution occurs. / The main application of this principle is calculating allele and genotype frequencies in a population.

6 / In a population, the sum frequency of alleles will equal 1. / This can be expressed as: / p + q = 1 / Where: / p = frequency of the dominant allele / q = frequency of recessive allele / In a population, the sum frequency of alleles will equal 1. / This can be expressed as: / p + q = 1 / Where: / p = frequency of the dominant allele / q = frequency of recessive allele

7 Hardy-Weinberg Equation / p 2 + 2pq + q 2 = 1 / Where: / p 2 = frequency of individuals homozygous for the dominant allele / 2pq = frequency of heterozygous individuals / q 2 = frequency of individuals homozygous for the recessive allele / p 2 + 2pq + q 2 = 1 / Where: / p 2 = frequency of individuals homozygous for the dominant allele / 2pq = frequency of heterozygous individuals / q 2 = frequency of individuals homozygous for the recessive allele


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