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Genetic Drift

Genetic Drift

Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.

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.

Gene Flow

Gene Flow

Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.

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).

Genetic Variation

Genetic Variation

Genetic variation is the diversity in DNA sequences found among individuals of the same species. This diversity is crucial for a species' survival because it helps organisms adapt to environmental changes. Genetic variation begins with fertilization, where an egg and sperm cell merge. Each of these cells carries 23 chromosomes, up to 46 in the fertilized egg. Chromosomes are long DNA strands that contain genes, the basic units of heredity.
Genes exist in different versions called alleles,...

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.

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Related Experiment Video

Updated: Mar 24, 2026

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila

Published on: August 20, 2019

Common genetic pools between human populations.

A Sanchez-Mazas¹, A Langaney

¹Laboratoire de Génétique et Biométrie, Université de Genève, Carouge-Genève, Switzerland.

|February 1, 1988

Summary

This summary is machine-generated.

Modern human origins trace back to an Occidental-Oriental split, shaping the human gene pool. This genetic divergence is supported by immunological data, contrasting with some DNA studies.

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Published on: August 20, 2019

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Detection of Rare Genomic Variants from Pooled Sequencing Using SPLINTER

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Published on: June 23, 2012

Area of Science:

Human evolution
Population genetics
Immunogenetics

Background:

Understanding modern human origins is crucial for tracing population genetic divergences.
Classical blood group analyses and DNA studies offer different perspectives on human evolutionary history.

Purpose of the Study:

To investigate the origins of modern human gene pool divergences.
To provide new evidence for an Occidental-Oriental population split as a key event.

Main Methods:

Analysis of common genetic pools from selected population samples.
Examination of highly informative immunological polymorphisms.
Comparison with preliminary DNA restriction fragment length polymorphism (RFLP) studies.

Main Results:

New evidence suggests an Occidental-Oriental population split as the primary driver of human gene pool divergence.
The study discusses the most likely ancestral genetic profile based on the findings.
Contradictions arise when comparing immunological data with preliminary DNA RFLP findings.

Conclusions:

The Occidental-Oriental split is presented as a significant event in human evolutionary history.
Immunological polymorphisms offer valuable insights into human origins.
Further research is needed to reconcile conflicting data from different genetic analyses.