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...

Position-effect Variegation

Position-effect Variegation

In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.

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...

Exon Recombination

Exon Recombination

The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...

Complementation Tests

Complementation Tests

A complementation test is a simple cross to identify whether the two mutations are located on the same gene or different genes. It was first performed by Edward Lewis in the 1940s while working on fruit flies. He developed the test to identify the location and arrangement of different mutations on chromosomes.
Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...

Limits to Natural Selection

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.For one, natural selection can only act upon existing genetic variation. Hypothetically, redtusks may enhance elephant survival by deterring ivory-seeking poachers. However, if there are no gene variants—or alleles—for redtusks, natural selection cannot increase the prevalence of...

You might also read

Related Articles

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

Sort by

Same author

Genomic and transcriptomic insights into color pigmentation variation in barred chickens.

Poultry science·2026

Same author

Structural Coloration and Carotenoids Together Create the Vibrant Colors of Peafowl Feathers.

Animals : an open access journal from MDPI·2026

Same author

Genomic and transcriptomic analyses revealed potential candidate genes for egg production traits in domesticated ducks.

Poultry science·2026

Same author

Genetic Parameters of Egg Quality Traits and Albumen Density in White Leghorn Chickens.

Animals : an open access journal from MDPI·2026

Same author

Genome-wide analysis reveals signatures of artificial selection in Pekin ducks across decades of breeding.

Poultry science·2026

Same author

Phylogeny of waterfowl (Anseriformes) constructed using genome sequences provides insights into topological incongruences.

Molecular biology and evolution·2026

Search research articles

Related Experiment Video

Updated: Jul 2, 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

Positive diversifying selection in avian Mx genes.

Sofia Berlin¹, Lujiang Qu, Xianyao Li

¹Department of Evolutionary Biology, Uppsala University, Norbyvagen 18 D, 752 36, Uppsala, Sweden.

|August 30, 2008

Summary

This summary is machine-generated.

Avian Mx genes show signs of positive selection, suggesting rapid evolution to combat RNA viruses. This molecular adaptation indicates that genetic diversity in Mx proteins may enhance pathogen resistance in birds.

More Related Videos

Genome Editing in Astyanax mexicanus Using Transcription Activator-like Effector Nucleases (TALENs)

Genome Editing in Astyanax mexicanus Using Transcription Activator-like Effector Nucleases (TALENs)

Published on: June 20, 2016

Related Experiment Videos

Last Updated: Jul 2, 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

Genome Editing in Astyanax mexicanus Using Transcription Activator-like Effector Nucleases (TALENs)

Genome Editing in Astyanax mexicanus Using Transcription Activator-like Effector Nucleases (TALENs)

Published on: June 20, 2016

Area of Science:

Molecular evolution
Immunogenetics
Avian biology

Background:

Mx proteins are interferon-induced GTPases crucial for antiviral defense against RNA viruses.
Understanding the evolutionary dynamics of Mx genes provides insights into host-pathogen interactions.

Purpose of the Study:

To analyze the molecular evolution of the Mx gene in birds.
To investigate selective pressures acting on avian Mx genes.
To explore the role of Mx gene diversity in antiviral defense.

Main Methods:

Analysis of interspecific divergence in Anseriformes and Galliformes.
Assessment of intraspecific diversity in chicken lines, Chinese breeds, and mallards.
Estimation of substitution rates (dN/dS) and Tajima's D values.

Main Results:

An unusually high dN/dS ratio (0.80) suggests relaxed constraint or positive selection.
11-18 codons identified under positive selection, primarily in the N-terminal avian-specific region.
Excess of non-synonymous polymorphisms and positive Tajima's D values indicate balancing selection.

Conclusions:

Avian Mx genes are evolving under positive and balancing selection, mimicking the Major Histocompatibility Complex (MHC).
Heterozygous individuals may possess enhanced ability to withstand pathogen attacks due to Mx gene diversity.
This evolutionary pattern highlights the dynamic interplay between viral pressures and avian immune gene adaptation.