Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

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 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.

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.

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.

Frequency-dependent Selection

Frequency-dependent Selection

When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.

Conservation of Small Populations

Conservation of Small Populations

Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

A Mitochondrial Plasma Proteomic Signature Identifies Metastatic Chromophobe Renal Cell Carcinoma.

Cancers·2026

Same author

NOT-gated chimeric antigen receptor circuits in T and NK cells.

Cell systems·2026

Same author

Growth-dependent sensory bet-hedging enhances collective navigation.

bioRxiv : the preprint server for biology·2026

Same author

Clear Cell Adenocarcinoma of the Urinary Tract Arising in a Young Man With the Congenital Malformation Disorder Opitz Syndrome: A Case Report.

International journal of surgical pathology·2026

Same author

<i>E. coli</i> chemosensing accuracy is not limited by stochastic molecule arrivals.

Nature physics·2026

Same author

Potassium ion homeostasis modulates mitochondrial function.

The Journal of cell biology·2026

Same journal

Common xenobiotics modulate gut microbial responses to low‑calorie sweeteners in vitro.

Molecular systems biology·2026

Same journal

ParTIpy: a scalable framework for archetypal analysis and Pareto task inference.

Molecular systems biology·2026

Same journal

Quantitative interactome mapping of skeletal muscle insulin resistance.

Molecular systems biology·2026

Same journal

Interpretable multi-omics integration across mixed-order tensors with MANTRA.

Molecular systems biology·2026

Same journal

To cleave or not to cleave: a systemic evaluation of DSS versus DSSO for cross-linking mass spectrometry analysis.

Molecular systems biology·2026

Same journal

Multiscale learning of gene network-driven phenotypic dynamics of single cells.

Molecular systems biology·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Mar 9, 2026

High-Throughput Live Imaging of Microcolonies to Measure Heterogeneity in Growth and Gene Expression

High-Throughput Live Imaging of Microcolonies to Measure Heterogeneity in Growth and Gene Expression

Published on: April 18, 2021

Non-genetic diversity modulates population performance.

Adam James Waite¹, Nicholas W Frankel¹, Yann S Dufour¹

¹Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA.

Molecular Systems Biology

|December 21, 2016

Summary

This summary is machine-generated.

Individual cell differences, or non-genetic diversity, can drive population-level adaptation. This study reveals how varying cell phenotypes impact collective bacterial function and adaptation, offering a new perspective on evolutionary processes.

Keywords:

Jensen's inequality cellular motility chemotaxis nonlinear systems non‐genetic diversity

More Related Videos

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Published on: February 3, 2023

Digital PCR-based Competitive Index for High-throughput Analysis of Fitness in Salmonella

Digital PCR-based Competitive Index for High-throughput Analysis of Fitness in Salmonella

Published on: May 13, 2019

Related Experiment Videos

Last Updated: Mar 9, 2026

High-Throughput Live Imaging of Microcolonies to Measure Heterogeneity in Growth and Gene Expression

High-Throughput Live Imaging of Microcolonies to Measure Heterogeneity in Growth and Gene Expression

Published on: April 18, 2021

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Published on: February 3, 2023

Digital PCR-based Competitive Index for High-throughput Analysis of Fitness in Salmonella

Digital PCR-based Competitive Index for High-throughput Analysis of Fitness in Salmonella

Published on: May 13, 2019

Area of Science:

Microbiology
Systems Biology
Evolutionary Biology

Background:

Biological functions rely on cell populations with diverse phenotypes arising from identical genotypes.
Understanding how this non-genetic diversity influences population-level function is crucial for evolutionary insights.

Purpose of the Study:

To investigate the relationship between individual cell phenotype, non-genetic diversity, and collective chemotactic performance in Escherichia coli.
To establish a causal link between protein expression, diversity, and functional outcomes.

Main Methods:

Development of a microfluidic device for simultaneous measurement of phenotype and chemotaxis in thousands of individual Escherichia coli.
Manipulation of key chemotaxis protein expression to assess its impact on diversity and performance.
Construction of a phenotype-to-performance map.

Main Results:

Non-genetic diversity spontaneously generated spatial structure in wild-type Escherichia coli populations.
A causal relationship was confirmed between protein expression, non-genetic diversity, and predicted performance.
A nonlinear regime was identified in the phenotype-to-performance map.

Conclusions:

The shape of the phenotypic distribution significantly impacts collective bacterial performance, comparable to changes in the mean phenotype.
Selection may act on both the mean and the distribution shape of phenotypes during adaptation.
This work provides a comprehensive map from phenotype to collective performance, elucidating adaptation mechanisms.