The Red Queen Hypothesis is used to account for predator-prey co-evolution. The expression was coined by van Valen in 1973 as an analogy to Lewis Carroll's popular children's novel, Through the Looking Glass (1872).
In Looking Glass Land, the Queen tells Alice, "It takes all the running you can do, to keep in the same place." In evolutionary terms, it's an arms race; a species must continually adapt to a dynamic environment or risk extinction.
http://www.pbs.org/wgbh/evolution/library/01/5/l_015_03.html http://www.sci.sdsu.edu/classes/bio508/ParasiteHostPresenation/sld018.htm
