What Is the Red Queen Hypothesis?

Cheetah chasing topi
Predator-prey relationships are affected by the Red Queen Hypothesis. (Getty/Anup Shah)

Evolution is the changing in species over time. However, with the way ecosystems work on Earth, many species have close and important relationships to each other to ensure their survival. These symbiotic relationships, such as the predator-prey relationship, keep the biosphere running properly and keep species from going extinct. This means as one species evolves, it will affect the other species in some way.

This coevolution of the species is like an evolutionary arms race that insists that the other species in the relationship must also evolve in order to survive.

The “Red Queen” hypothesis in evolution is related to the coevolution of species. It states that species must constantly adapt and evolve to pass on genes to the next generation and also to keep from going extinct when other species within a symbiotic relationship are evolving. First proposed in 1973 by Leigh Van Valen, this part of the hypothesis is especially important in a predator-prey relationship or a parasitic relationship.

Predator and Prey

Food sources are arguably one of the most important types of relationships in regards to survival of a species. For instance, if a prey species evolves to become faster over a period of time, the predator needs to adapt and evolve in order to keep using the prey as a reliable food source.

Otherwise, the now faster prey will escape and the predator will lose a food source and potentially go extinct. However, if the predator becomes faster itself, or evolves in another way like becoming stealthier or a better hunter, then the relationship can continue and the predators will survive. According to the Red Queen hypothesis, this back and forth coevolution of the species is a constant change with smaller adaptations accumulating over long periods of time.

Sexual Selection

Another part of the Red Queen hypothesis has to do with sexual selection. It relates to the first part of the hypothesis as a mechanism to speed up evolution with the desirable traits. Species that are capable of choosing a mate rather than undergoing asexual reproduction or not having the ability to choose a partner can identify characteristics in that partner that are desirable and will produce the more fit offspring for the environment. Hopefully, this mixing of desirable traits will lead to the offspring being chosen through natural selection and the species will continue. This is a particularly helpful mechanism for one species in a symbiotic relationship if the other species does not have the ability to undergo sexual selection.

Host/Parasite

An example of this type of interaction would be a host and parasite relationship. Individuals wanting to mate in an area with an abundance of parasitic relationships may be on the lookout for a mate that seems to be immune to the parasite. Since most parasites are asexual or not able to undergo sexual selection, then the species that can choose an immune mate has an evolutionary advantage. The goal would be to produce offspring that have the trait that makes them immune to the parasite.

This would make the offspring more fit for the environment and more likely to live long enough to reproduce themselves and pass down the genes.

This hypothesis does not mean that the parasite in this example would not be able to coevolve. There are more ways to accumulate adaptations than just sexual selection of partners. DNA mutations can also produce a change in the gene pool just by chance. All organisms, regardless of their reproduction style can have mutations happen at any time. This allows all species, even parasites, to coevolve as the other species in their symbiotic relationships also evolve.