The Red Queen hypothesis is a hypothesis in evolutionary biology proposed in 1973, that species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species

Basically saying that every species is constantly evolving towards a local optimum (it's niche), but that since that niche is made up of other species who are also evolving, the local optimum is always moving, so it becomes kind of like the three-body problem.

From the article:

Van Valen named the hypothesis "Red Queen" because under his hypothesis, species have to "run" or evolve in order to stay in the same place, or else go extinct. As the Red Queen said to Alice in Lewis Carroll's Through the Looking-Glass in her explanation of the nature of Looking-Glass Land:

Now, here, you see, it takes all the running you can do, to keep in the same place.