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Hardy weinberg law

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Srishti Aggrawal

Srishti Agrawal presented on the Hardy-Weinberg law to Dr. Ajay Kumar. The Hardy-Weinberg law states that allele and genotype frequencies remain constant between generations in a population if it is large, mates randomly, has no migration, mutation, or selection. The law assumes organisms are diploid, reproduce sexually, have non-overlapping generations, random mating, an infinitely large population, equal allele frequencies between sexes. Violations of random mating can change frequencies from Hardy-Weinberg proportions. Selection, genetic drift, migration, and mutation can also influence allele and genotype frequencies across generations.

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PRESENTED BY : SRISHTI AGGRAWAL M.SC BOTANY DEPT.OF SCIENCE DEI,AGRA PRESENTED TO : Dr. AJAY KUMAR DEPT.OF SCIENCE DEI,AGRA
Hardy weinberg law
HARDY-WEINBERG LAW The HardyWeinberg principle, also known as the HardyWeinberg equilibrium, model, theorem, or law, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. These influences include mate choice, mutation, selection, genetic drift, gene flow
organisms are diploid only sexual reproduction occurs generations are nonoverlapping mating is random population size is infinitely large allele frequencies are equal in the sexes there is no migration, mutation or selection
Random mating. The HWP states the population will have the given genotypic frequencies (called Hardy Weinberg proportions) after a single generation of random mating within the population. When the random mating assumption is violated, the population will not have HardyWeinberg proportions. A common cause of non-random mating is inbreeding, which causes an increase in homozygosity for all genes.
Selection, in general, causes allele frequencies to change, often quite rapidly.
While directional selection eventually leads to the loss of all alleles except the favored one (unless one allele is dominant, in which case recessive alleles can survive at low frequencies), some forms of selection, such as balancing selection, lead to equilibrium without loss of alleles.
Mutation will have a very subtle effect on allele frequencies. Mutation rates are of the order 104 to 108, and the change in allele frequency will be, at most, the same order. Recurrent mutation will maintain alleles in the population, even if there is strong selection against them.
Small population size can cause a random change in allele frequencies. This is due to a sampling effect, and is called genetic drift. Sampling effects are most important when the allele is present in a small number of copies.
Migration genetically links two or more populations together. In general, allele frequencies will become more homogeneous among the populations. Some models for migration inherently include nonrandom mating (Wahlund effect, for example). For those models, the HardyWeinberg proportions will normally not be valid.
Hardy weinberg law

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Hardy weinberg law

  • 1. PRESENTED BY : SRISHTI AGGRAWAL M.SC BOTANY DEPT.OF SCIENCE DEI,AGRA PRESENTED TO : Dr. AJAY KUMAR DEPT.OF SCIENCE DEI,AGRA
  • 3. HARDY-WEINBERG LAW The HardyWeinberg principle, also known as the HardyWeinberg equilibrium, model, theorem, or law, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. These influences include mate choice, mutation, selection, genetic drift, gene flow
  • 4. organisms are diploid only sexual reproduction occurs generations are nonoverlapping mating is random population size is infinitely large allele frequencies are equal in the sexes there is no migration, mutation or selection
  • 5. Random mating. The HWP states the population will have the given genotypic frequencies (called Hardy Weinberg proportions) after a single generation of random mating within the population. When the random mating assumption is violated, the population will not have HardyWeinberg proportions. A common cause of non-random mating is inbreeding, which causes an increase in homozygosity for all genes.
  • 6. Selection, in general, causes allele frequencies to change, often quite rapidly.
  • 7. While directional selection eventually leads to the loss of all alleles except the favored one (unless one allele is dominant, in which case recessive alleles can survive at low frequencies), some forms of selection, such as balancing selection, lead to equilibrium without loss of alleles.
  • 8. Mutation will have a very subtle effect on allele frequencies. Mutation rates are of the order 104 to 108, and the change in allele frequency will be, at most, the same order. Recurrent mutation will maintain alleles in the population, even if there is strong selection against them.
  • 9. Small population size can cause a random change in allele frequencies. This is due to a sampling effect, and is called genetic drift. Sampling effects are most important when the allele is present in a small number of copies.
  • 10. Migration genetically links two or more populations together. In general, allele frequencies will become more homogeneous among the populations. Some models for migration inherently include nonrandom mating (Wahlund effect, for example). For those models, the HardyWeinberg proportions will normally not be valid.