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May 20, 2024 · This calculator computes the frequency of phenotypes based on the genetic makeup of a population. It uses the Hardy-Weinberg equilibrium, a principle that assumes no evolutionary influences affect the population. This provides a static snapshot of phenotype distribution across generations.
Jul 19, 2024 · The allele frequency calculator checks how often a gene occurs in the population, based on the prevalence of the disease it causes, using the Hardy-Weinberg equation.
The relationship between allele frequencies and genotype frequencies in populations at Hardy-Weinberg Equilibrium is usually described using a trait for which there are two alleles present at the locus of interest. This calculator demonstrates the application of the Hardy-Weinberg equations to loci with more than two alleles.
Jun 17, 2024 · Hardy-Weinberg Equilibrium Calculator. The calculator below uses the Hardy-Weinberg equation to estimate the frequency of different genotypes for autosomal traits. Select input of choice and fill values.
- Overview
- Key points:
- Darwin meets Mendel—not literally
- Microevolution and population genetics
- Populations
- Alleles
- Allele frequency
- Example: Finding allele frequency
- The gene pool
How to find allele frequency and how it's different from genotype frequency. What a gene pool is.
•Microevolution is a change in the frequency of gene variants, alleles, in a population, typically occurring over a relatively short time period.
•Population genetics is the field of biology that studies allele frequencies in populations and how they change over time.
•Allele frequency refers to how common an allele is in a population. It is determined by counting how many times the allele appears in the population then dividing by the total number of copies of the gene.
Frequency of allele A = Number of copies of allele Ain populationTotal number of copies of gene in population
•The gene pool of a population consists of all the copies of all the genes in that population.
•Microevolution is a change in the frequency of gene variants, alleles, in a population, typically occurring over a relatively short time period.
•Population genetics is the field of biology that studies allele frequencies in populations and how they change over time.
•Allele frequency refers to how common an allele is in a population. It is determined by counting how many times the allele appears in the population then dividing by the total number of copies of the gene.
Frequency of allele A = Number of copies of allele Ain populationTotal number of copies of gene in population
When Darwin came up with his theories of evolution and natural selection, he knew that the processes he was describing depended on heritable variation in populations. That is, they relied on differences in the features of the organisms in a population and on the ability of these different features to be passed on to offspring.
[Read a quick recap of evolution and natural selection.]
Darwin did not, however, know how traits were inherited. Like other scientists of his time, he thought that traits were passed on via blending inheritance. In this model, parents' traits are supposed to permanently blend in their offspring. The blending model was disproven by Austrian monk Gregor Mendel, who found that traits are specified by non-blending heritable units called genes.
Although Mendel published his work on genetics just a few years after Darwin published his ideas on evolution, Darwin probably never read Mendel’s work. Today, we can combine Darwin’s and Mendel’s ideas to arrive at a clearer understanding of what evolution is and how it takes place.
Microevolution, or evolution on a small scale, is defined as a change in the frequency of gene variants, alleles, in a population over generations. The field of biology that studies allele frequencies in populations and how they change over time is called population genetics.
Microevolution is sometimes contrasted with macroevolution, evolution that involves large changes, such as formation of new groups or species, and happens over long time periods. However, most biologists view microevolution and macroevolution as the same process happening on different timescales. Microevolution adds up gradually, over long periods of time to produce macroevolutionary changes.
A population is a group of organisms of the same species that are found in the same area and can interbreed. A population is the smallest unit that can evolve—in other words, an individual can’t evolve.
An allele is a version of a gene, a heritable unit that controls a particular feature of an organism.
For instance, Mendel studied a gene that controls flower color in pea plants. This gene comes in a white allele, w, and a purple allele, W. Each pea plant has two gene copies, which may be the same or different alleles. When the alleles are different, one—the dominant allele, W—may hide the other—the recessive allele, w. A plant's set of alleles, called its genotype, determines its phenotype, or observable features, in this case flower color.
Allele frequency refers to how frequently a particular allele appears in a population. For instance, if all the alleles in a population of pea plants were purple alleles, W, the allele frequency of W would be 100%, or 1.0. However, if half the alleles were W and half were w, each allele would have an allele frequency of 50%, or 0.5.
In general, we can define allele frequency as
Frequency of allele A = Number of copies of allele Ain populationTotal number ofA/a gene copies in population
Sometimes there are more than two alleles in a population (e.g., there might be A, a, and Ai alleles of a gene). In that case, you would want to add up all of the different alleles to get your denominator.
Let’s look at an example. Consider the very small population of nine pea plants shown below. Each pea plant has two copies of the flower color gene.
If we look at the two gene copies in each plant and count up how many W copies are present, we find there are 13. If we count up how many w copies are present, we find that there are five. The total number of gene copies in the whole population is 13+5=18 .
We can divide the number of copies of each allele by the total number of copies to get the allele frequency. By convention, when there are just two alleles for a gene in a population, their frequencies are given the symbols p and q :
p=frequency ofW = 13/18 = 0.72 , or 72%
q=frequency ofw = 5/18 = 0.28 , or 28%
The frequencies of all the alleles of a gene must add up to one, or 100%.
The total set of gene copies for all genes in a population is referred to as its gene pool. The gene pool gets its name from the idea that we are essentially taking all the gene copies—for all genes—in the individuals of a population and dumping them into one large, common pool.
What would this look like? In the example above, we went through all nine individuals in the population and looked at their copies of the flower color gene. There were 18 individual gene copies, each of which was a W or a w allele. Now, imagine that we went through this same process for every single gene in the pea plant, including genes that control height, seed color, seed shape, metabolism, etc. There would be 18 copies of each gene pulled out and dumped into the common pool. At the end of this process, the common pool of gene copies will be the gene pool of our population.
By looking at all the copies of all the genes in a population, we can see globally how much genetic variation there is in the population. The more variation a population has, the better its ability to adapt to changes in its environment through natural selection. If there is more variation, the odds are better that there will be some alleles already present that allow organisms to survive and reproduce effectively under the new conditions.
[Attribution and references]
In this calculator, Hardy-Weinberg equilibrium can be used to calculate the expected common homozygotes, expected heterozygotes, expected rare homozygotes and the frequency range of the 2 (p and q) alleles from the observed genotypes.
People also ask
How do you calculate genotype frequency?
How do you calculate genotypes?
What is the relationship between allele frequencies and genotype frequencies?
How do you calculate allele frequency?
The calculator below uses the Hardy-Weinberg equation: p²+ 2pq+ q² = 1. to estimate the frequency of the carrier state (2pq) for an autosomal recessive trait . SELECT % OR PROPORTION THEN ENTER VALUE. Example : Cystic fibrosis (CF) Where: A is the wild type allele. a is the cystic fibrosis mutation.
