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

Types of Selection

Types of Selection

Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural selection can be directional, stabilizing, or disruptive. Directional selection favors one extreme trait and shifts the population towards that phenotype while selecting against individuals displaying alternate traits. Stabilizing selection favors an intermediate trait with a narrow range of variation. Deviation from the optimal phenotype towards an...

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.Positive Frequency-Dependent SelectionIn positive...

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).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...

Background and Environment Affect Phenotype

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...

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.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...

Speciation Rates

Speciation Rates

Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.

You might also read

Related Articles

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

Sort by

Same author

Adhesion and polarity-driven morphogenesis: Mechanisms and constraints in tissue formation.

PLoS computational biology·2026

Same author

Modeling time to visual insight in Mooney image recognition with a chaotic recurrent neural network.

Cognitive neurodynamics·2026

Same author

Conserved rod-to-spherical shape transitions in Escherichia coli through primordial experimental adaptations.

Bioscience reports·2026

Same author

Revealing Cell Envelope Heterogeneity in Two Stable <i>Escherichia coli</i> L-Forms.

International journal of molecular sciences·2026

Same author

Enzyme as Maxwell's Demon: Steady-State Deviation from Chemical Equilibrium by Enhanced Enzyme Diffusion.

Physical review letters·2026

Same author

Stability control of metastable states as a unified mechanism for flexible temporal modulation in cognitive processing.

Neural networks : the official journal of the International Neural Network Society·2025

Search research articles

Related Experiment Video

Updated: Jun 23, 2026

Measuring Microbial Mutation Rates with the Fluctuation Assay

Measuring Microbial Mutation Rates with the Fluctuation Assay

Published on: November 28, 2019

How selection affects phenotypic fluctuation.

Yoichiro Ito¹, Hitoshi Toyota, Kunihiko Kaneko

¹Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Suita, Osaka, Japan.

Molecular Systems Biology

|April 30, 2009

Summary

This summary is machine-generated.

Phenotypic fluctuation, or bet-hedging, can enhance cell survival in changing environments. Evolution under strong selection can increase this fluctuation, aiding survival by generating diverse phenotypes.

More Related Videos

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

Related Experiment Videos

Last Updated: Jun 23, 2026

Measuring Microbial Mutation Rates with the Fluctuation Assay

Measuring Microbial Mutation Rates with the Fluctuation Assay

Published on: November 28, 2019

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

Area of Science:

Evolutionary Biology
Genetics
Microbiology

Background:

Phenotypic fluctuation in isogenic cells, driven by stochastic gene expression, can provide a bet-hedging advantage in variable environments.
While typically suppressed under stable conditions, phenotypic diversity from fluctuation may aid survival even in single selective environments.

Purpose of the Study:

To investigate if phenotypic fluctuation increases during evolution.
To explore the evolutionary strategies cells employ under strong selection pressure.

Main Methods:

Cycles of mutation and selection for increased GFP fluorescence in Escherichia coli.
Analysis of mutant genotypes exhibiting broad fluorescence distributions.

Main Results:

Mutant genotypes with broad GFP fluorescence distributions and low average values emerged under strong selection.
Increased phenotypic fluctuation was linked to variance in mRNA abundance.
These 'broad mutants' arose independently across the phylogenetic tree.

Conclusions:

Increased phenotypic fluctuation is an evolutionary strategy that can emerge under severe selective pressures.
This strategy enhances survival by generating extreme phenotypes and increasing phenotypic diversity, similar to mutation.