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Hardy-Weinberg Principle

Hardy-Weinberg Principle

Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the gene pool of the population. The gene pool of a population is the sum of every allele of all genes within that population and has some degree of variation. Genetic variation is typically expressed as a relative frequency, which is the percentage of the total population that has a given allele, genotype or phenotype.

What is Population Genetics?

What is Population Genetics?

A population is composed of members of the same species that simultaneously live and interact in the same area. When individuals in a population breed, they pass down their genes to their offspring. Many of these genes are polymorphic, meaning that they occur in multiple variants. Such variations of a gene are referred to as alleles. The collective set of all the alleles within a population is known as the gene pool.

Trihybrid Crosses

Trihybrid Crosses

Trihybrid Crosses
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...

Punnett Squares

Punnett Squares

Punnett Squares

Punnett Squares

Mutation, Gene Flow, and Genetic Drift

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).

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Updated: May 24, 2026

Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR

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Patterns for four-allele population genetics model.

Linlin Su¹, Roger Lui

¹Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, United States. lsu@wpi.edu

Theoretical Population Biology

|March 8, 2012

Summary

This summary is machine-generated.

This study classifies population genetics patterns for four-allele models. Researchers identified 117 distinct patterns, offering insights into long-term genetic diversity and population structures.

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Area of Science:

Population Genetics
Mathematical Biology
Evolutionary Dynamics

Background:

Understanding allele frequency dynamics is crucial for predicting population evolution.
Existing patterns of stable equilibria in population genetics models inform long-term genetic makeup.
Previous studies have characterized patterns for two- and three-allele models.

Purpose of the Study:

To find and classify all existing patterns for single-locus, four-allele population genetics models in continuous time.
To describe the domains of attraction for coexisting asymptotically stable equilibria.
To contribute to the prediction of long-term genetic population structures.

Main Methods:

Analysis of a system of differential equations defining population allele frequencies and fitness.
Classification of asymptotically stable equilibria.
Characterization of existing patterns based on allele interactions.

Main Results:

Identified and classified 117 distinct existing patterns for the four-allele model.
Characterized the domains of attraction for these stable equilibria.
Demonstrated that the continuous-time model yields the same equilibria and stability as the discrete-time model.

Conclusions:

The four-allele model exhibits a significantly larger number of complex evolutionary patterns compared to simpler models.
These findings enhance our ability to predict the long-term genetic composition of populations with multiple alleles.
The study provides a comprehensive framework for analyzing multi-allele population dynamics.