Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

What is Natural Selection?01:32

What is Natural Selection?

129.6K
Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become more common within a population or species. Naturally selected traits initially arise via random genetic mutations. In order for selection to occur, there must be variation within a population, the trait controlling the variation must be heritable, and there must be an evolutionary advantage for variation in the trait.
129.6K
Antibiotic Selection00:57

Antibiotic Selection

60.0K
Overview
60.0K
Types of Selection01:46

Types of Selection

45.2K
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...
45.2K
Frequency-dependent Selection01:21

Frequency-dependent Selection

24.2K
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.
24.2K
Limits to Natural Selection01:38

Limits to Natural Selection

35.2K
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.
35.2K
Natural Selection and Adaptation01:15

Natural Selection and Adaptation

1.4K
Natural selection, a fundamental concept in evolutionary biology, is the mechanism by which evolution is driven, favoring organisms that are best adapted to their environments. This process enhances their chances of survival and reproduction. Adaptation, a key outcome of this process, involves genetic modifications that optimize an organism's functionality under specific environmental challenges, such as extreme cold or thinner air at high altitudes.
Beyond physical adaptations,...
1.4K

You might also read

Related Articles

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

Sort by
Same author

Draft assemblies for 177 bird species enhance genus-level coverage.

GigaScience·2026
Same author

Computer vision analysis to identify episodic flapping in hovering hummingbirds.

Biology open·2026
Same author

Scaling and foraging behaviour drive the evolution of humeral shape in hummingbirds.

Proceedings. Biological sciences·2026
Same author

Convergent mechanisms, divergent strategies: a comparison of nectar intake between a generalist and a specialist bat species.

The Journal of experimental biology·2026
Same author

Convergent and lineage-specific genomic changes shape adaptations in sugar-consuming birds.

Science (New York, N.Y.)·2026
Same author

Sharper, straighter, stiffer, stronger: sexually dimorphic bill shape enhances male stabbing performance in the green hermit hummingbird (Phaethornis guy).

The Journal of experimental biology·2025

Related Experiment Video

Updated: Feb 8, 2026

Author Spotlight: Development of an Automated Camera-Based System for Real-Time Blast Overpressure Monitoring and TBI Risk Assessment in Military Training
06:20

Author Spotlight: Development of an Automated Camera-Based System for Real-Time Blast Overpressure Monitoring and TBI Risk Assessment in Military Training

Published on: December 6, 2024

3.1K

Intrasexually selected weapons.

Alejandro Rico-Guevara1,2,3, Kristiina J Hurme1,2

  • 1Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.

Biological Reviews of the Cambridge Philosophical Society
|June 21, 2018
PubMed
Summary

Intrasexually selected weapons (ISWs) are traits evolved for same-sex combat. These weapons appear independently in various animal groups and are often modified feeding or locomotor structures, primarily in males.

Keywords:
agonistic behaviouranimal armamentsexaggerated traitsintrasexual combatmale-male competitionsecondary sexual weaponssex-specific weapons

More Related Videos

Selective Harvesting of Marginating-hepatic Leukocytes
06:53

Selective Harvesting of Marginating-hepatic Leukocytes

Published on: July 21, 2016

6.0K
The Lambda Select cII Mutation Detection System
07:08

The Lambda Select cII Mutation Detection System

Published on: April 26, 2018

8.4K

Related Experiment Videos

Last Updated: Feb 8, 2026

Author Spotlight: Development of an Automated Camera-Based System for Real-Time Blast Overpressure Monitoring and TBI Risk Assessment in Military Training
06:20

Author Spotlight: Development of an Automated Camera-Based System for Real-Time Blast Overpressure Monitoring and TBI Risk Assessment in Military Training

Published on: December 6, 2024

3.1K
Selective Harvesting of Marginating-hepatic Leukocytes
06:53

Selective Harvesting of Marginating-hepatic Leukocytes

Published on: July 21, 2016

6.0K
The Lambda Select cII Mutation Detection System
07:08

The Lambda Select cII Mutation Detection System

Published on: April 26, 2018

8.4K

Area of Science:

  • Evolutionary Biology
  • Animal Behavior
  • Morphology

Background:

  • Secondary sex traits evolve through various mechanisms, including sexual selection.
  • Distinguishing weaponry used in same-sex combat from other sexually selected traits is crucial for understanding evolutionary patterns.

Purpose of the Study:

  • To define and review intrasexually selected weapons (ISWs) across the animal kingdom.
  • To understand the evolutionary patterns and distinctiveness of ISWs compared to other weaponry and sex traits.
  • To propose hypotheses explaining the evolution and distribution of ISWs.

Main Methods:

  • A comprehensive review of morphological, ontogenetic, and behavioral data across the animal phylogeny.
  • Classification of traits as ISWs based on presence/enlargement in adults of one sex and use in intrasexual combat.
  • Exclusion of fossil records due to limited behavioral and ontogenetic data.

Main Results:

  • ISWs are found in bilateral animals, evolving independently in nematodes, arthropods, and vertebrates.
  • Most ISWs are paired, located near the head, are modifications of skeletal structures, feeding, or locomotor appendages, and are more developed in males.
  • ISWs are common in terrestrial taxa, used for guarding mates/territories, and in signaling displays; they are less common in species with hunting habits.

Conclusions:

  • ISWs represent a distinct category of sexually selected traits shaped by same-sex combat.
  • The independent evolution and specific characteristics of ISWs provide insights into sexual selection and competition.
  • Further behavioral and morphological studies are warranted for taxa with potential ISWs.