Related Experiment Video
Updated: Jun 5, 2026
13:55
Sexual Transmission of American Trypanosomes from Males and Females to Naive Mates
Published on: January 27, 2019
Parasites and sex: Catching the red queen
1Richard Ladle is at the Dept of Zoology, University of Oxford, South Parks Road, Oxford, UK OXI 3PS.
Trends in Ecology & Evolution
|January 18, 2011
Summary
The Red Queen hypothesis proposes that parasites drive the evolution of sexual reproduction. Studies show parasites increase in frequency-dependent ways, supporting sex as an evolutionary advantage against disease.
Area of Science:
- Evolutionary biology
- Parasitology
- Reproductive strategies
Background:
- The Red Queen hypothesis posits that sexual reproduction persists due to coevolutionary arms races, particularly between hosts and parasites.
- Antagonistic biotic interactions are theorized to offset the inherent inefficiencies of sexual reproduction.
- Previous research has explored the link between parasite-host dynamics and the maintenance of sex.
Purpose of the Study:
- To investigate the role of parasites in maintaining sexual reproduction.
- To provide empirical evidence for the Red Queen hypothesis in the context of host-parasite coevolution.
- To examine the selective pressures imposed by parasites on reproductive strategies.
Main Methods:
- Experimental studies were conducted to assess host-parasite interactions.
- Negative frequency-dependent selection was analyzed in relation to parasite prevalence.
- Parasite load in parthenogenetic versus sexual populations was compared.
- Correlations between genetic recombination rates and parasitic chromosome frequencies were examined.
Main Results:
- Experimental evidence demonstrated negative frequency-dependent selection.
- Parthenogenetic lineages exhibited higher parasite loads compared to sympatric sexual populations.
- A positive correlation was observed between the rate of genetic recombination and the prevalence of parasitic chromosomes.
- These findings strongly support the role of parasites in maintaining sex.
Conclusions:
- Parasites play a significant role in maintaining sexual reproduction.
- The Red Queen hypothesis is empirically supported by host-parasite coevolutionary dynamics.
- Sexual reproduction provides an evolutionary advantage in combating parasitic infections.
Related Concept Videos
01:22Microbial Interactions: Parasitism
Parasitism is a form of microbial interaction in which parasitic microbes exploit a host organism for nutrients and shelter, often at the host's expense. Unlike mutualistic relationships, where both organisms benefit, parasitism benefits only the parasite and harms the host.Classification of ParasitesMicrobial parasites are broadly classified based on their location relative to the host.Ectoparasites remain on the host’s surface, such as the skin or outer tissues, drawing nutrients...
01:18Trichomoniasis
Trichomonas vaginalis is a flagellated protozoan parasite and the causative agent of trichomoniasis, one of the most prevalent non-viral sexually transmitted infections in the United States. This extracellular parasite primarily colonizes the lower genitourinary tract in women—particularly the vagina—and in men, the urethra and prostate. Its structural and functional adaptations enable its survival, motility, and pathogenicity within the host environment.Structural Features and Host EntryT.
00:57Inclusive Fitness
Most altruistic behavior—in which one animal helps another at a cost to themselves—occurs between relatives. Scientists think these altruistic behaviors evolved because they increase the inclusive fitness of the animal providing help.
01:15Diversity of Protists I
Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...
00:58Symbiosis
Symbiotic relationships are long-term, close interactions between individuals of different species that affect the distribution and abundance of those species. When a relationship is beneficial to both species, this is called mutualism. When the relationship is beneficial to one species but neither beneficial nor harmful to the other species, this is called commensalism. When one organism is harmed to benefit another, the relationship is known as parasitism. These types of relationships often...
01:27Diversity of Protists II
Alveolates are a group of organisms recognized by the presence of alveoli, which are cytoplasmic sacs located beneath the cell membrane. While their function remains uncertain, alveoli may help regulate water balance by controlling how much water enters and leaves the cell. In dinoflagellates, these structures may serve as armor plates. There are three major types of alveolates: ciliates, which move using cilia; dinoflagellates, which use flagella for movement; and apicomplexans, which are...