How to Find Allele, Genotype and Phenotype Frequencies

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Nikolay's Genetics Lessons

Nikolay's Genetics Lessons

Күн бұрын

Hardy-Weinberg equilibrium
The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. When mating is random in a large population with no disruptive circumstances, the law predicts that both genotype and allele frequencies will remain constant because they are in equilibrium.
The Hardy-Weinberg equilibrium can be disturbed by a number of forces, including mutations, natural selection, nonrandom mating, genetic drift, and gene flow. For instance, mutations disrupt the equilibrium of allele frequencies by introducing new alleles into a population. Similarly, natural selection and nonrandom mating disrupt the Hardy-Weinberg equilibrium because they result in changes in gene frequencies. This occurs because certain alleles help or harm the reproductive success of the organisms that carry them. Another factor that can upset this equilibrium is genetic drift, which occurs when allele frequencies grow higher or lower by chance and typically takes place in small populations. Gene flow, which occurs when breeding between two populations transfers new alleles into a population, can also alter the Hardy-Weinberg equilibrium.
Because all of these disruptive forces commonly occur in nature, the Hardy-Weinberg equilibrium rarely applies in reality. Therefore, the Hardy-Weinberg equilibrium describes an idealized state, and genetic variations in nature can be measured as changes from this equilibrium state.

Пікірлер: 5
@Wmadanat64
@Wmadanat64 6 жыл бұрын
Does random genetic drift invalidate Hardy-Weinberg expected genotype frequencies?
@GeneticsLessons
@GeneticsLessons 6 жыл бұрын
Yes.
@Wmadanat64
@Wmadanat64 6 жыл бұрын
Why is that true? Is it because fixation equals mutation or k=u
@GeneticsLessons
@GeneticsLessons 6 жыл бұрын
If Hardy-Weinberg Equilibrium is achieved then no evolution occurs. To achieve the equilibrium five conditions must be met:1. Population must be very large.2. Population must be isolated from other populations (no immigration or emigration).3. No mutations4. Random mating5. No natural selection (i.e. every individual has an equal chance of survival)If the five conditions are not met then evolution occurs.
@Wmadanat64
@Wmadanat64 6 жыл бұрын
Thank you very much!
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