Red Queen hypothesis: a standalone construct

Leigh Van Valen introduced the Red Queen hypothesis in 1973 (A new evolutionary law, Evolutionary Theory), arguing that a species must keep evolving simply to hold its current level of fitness against the other species it lives among. He drew the name from the Red Queen in Lewis Carroll's Through the Looking-Glass, who tells Alice that "it takes all the running you can do, to keep in the same place": because predators, prey, competitors, and parasites are all adapting at the same time, any advantage one species gains is soon matched, so continual change buys no lasting lead and mainly staves off decline. Stenseth and Maynard Smith (1984) formalized the idea as coevolution driven by these living interactions rather than by the physical environment, and Brockhurst and colleagues (2014) reviewed the modern evidence that such biotic conflict is a primary engine of natural selection. What makes the hypothesis a landmark is that it was stated as a law about the pace and cause of adaptation: Van Valen tied it to his observation that the probability of extinction within a group stays roughly constant over time, which he read as a sign of steady, unrelenting pressure from co-evolving rivals. It now anchors research on host and parasite arms races, on frequency-dependent selection, and on long-standing questions such as why sexual reproduction persists.[1][2][3]

Unit

An evolutionary hypothesis about the pace and cause of adaptation, framed at the level of species and their biotic interactions

Recovery means

Not applicable

Measured by

Examined through coevolutionary models and empirical signatures such as reciprocal host and parasite arms races, frequency-dependent selection, and the roughly constant extinction probabilities Van Valen documented in fossil survivorship curves