If you’ve read our previous articles on Genetics and Inheritance, you might be wondering what a gene pool is. Simply put, it’s the different versions of genes in a group of individuals at a specific time. But how do we calculate the frequency of these genes? That’s where the Hardy-Weinberg Principle comes in. Using this equation, we can figure out how often a specific gene appears in a population. This is known as allelic frequency, which is just a fancy way of saying the number of times a gene shows up in a group of individuals.

What is the Hardy-Weinberg principle?

The Hardy-Weinberg principle is a mathematical equation that helps us calculate the frequency of an allele in a population at equilibrium. This principle states that the allele frequencies of a gene in a population will stay the same from one generation to the next, as long as there aren't any significant advantages or disadvantages linked. This'. An example of directional selection is the case of the peppered moth during the industrial revolution. Due to pollution, dark moths became more common as they were better suited to blending in with their environment and avoiding predators.

The Hardy-Weinberg principle gives us a formula to calculate the expected frequency of an allele in a population. We use the letters P, Q and A to represent the dominant homozygous frequency, heterozygous frequency, and recessive homozygous frequency respectively. If we know these frequencies, we can use the equation to find the expected frequency of an allele in a population.

What are the assumptions of the Hardy-Weinberg principle?

Let's imagine a organisms Hardyin provides model to predict the frequency of alleles in a However it's challenging to find a natural population that meets all five conditions of the model, such as random mating, an infinitely large population size, no migration, no selection, and no mutations. If we observe different frequencies than the ones the model, we can conclude that at least one of the conditions is not being met.

To calculate the allelic frequency, we can look at a specific example. Let's say we have a population of 10,000 humans, and we're studying the gene that controls hair colour. The dominant allele B results in brown hair, while the recessive allele b results in blonde hair. Each individual has two copies of this gene, making a total of 20,000 alleles in the population. If everyone in the population had blonde hair (homozygous recessive), the frequency of the b allele would be 100%, while the frequency of the B allele would be 0%.

However, things get more complicated when we consider heterozygous individuals. For example, if we cross two heterozygous individuals, we can use the number of B and b alleles to calculate the frequency of the b allele in the population. If there are 4 B alleles and 4 b alleles among the offspring, then there are a total of 20,000 alleles in the population, with 10,000 of each allele. Therefore, the allele frequency of the b allele is 50%.

What is the Hardy-Weinberg equation?

Where p² = BB, 2pq = Bb, and b² = aa.

Using the Hardy-Weinberg equation, we can calculate the frequency of an allele in a population. In this case, p² = BB represents the frequency of the dominant allele B, 2pq = Bb represents the frequency of heterozygotes, and b² = aa represents the frequency of the recessive allele b.

The equation for the Hardy-Weinberg principle is expressed as p² + 2pq + q² = 1.0, where p is the frequency of the dominant allele and q is the frequency of the recessive allele. Therefore, the frequency of the dominant allele is p², the frequency of the heterozygotes is 2pq, and the frequency of recessive allele².

Hardy-Weinberg Principle

What does the Hardy-Weinberg principle predict?

The Hardy-Weinberg principle predicts that at equilibrium, the allele frequencies of a gene within a population will not change from one generation to the next. 

What is the Hardy-Weinberg principle used for?

 It can be used to calculate the frequency of an allele in a population at equilibrium. The Hardy-Weinberg principle is also used as a null model in genetics. If the predicted allelic frequencies do not match the observed frequencies, we can conclude that at least one of the Hardy-Weinberg equilibrium conditions has not been met. 

What are the conditions of the Hardy-Weinberg principle?

There are 5 conditions for Hardy-Weinberg equilibrium. These are:- Mating is random.- The population size is infinitely large.-There is no migration: the population is isolated.-There is no selection: all alleles are equally likely to be passed on to the next generation.-No mutations arise.

‍