R ed Q ueen Theory

Abstract

Abstract The Red Queen theory was introduced to explain the apparent constancy of extinction rates. The theory states that extinction rates remain constant because taxa are in continuous evolutionary arms races with other taxa. This macroevolution version of the theory is not well supported. However, a microevolution version of the theory, in which species maintain constant levels of adaptation because of antagonistic coevolution, is well supported, especially for hosts and their parasites. The Red Queen hypothesis is now most often used to refer to the idea that host–parasite coevolution favours sexual reproduction. Meiotic recombination in hosts is proposed to generate rare genotypes, which are selectively favoured if parasites are adapted to the most common host genotypes. However, the genetic mechanism underlying the advantage of recombination in models of host–parasite coevolution is not entirely clear. Key Concepts The Red Queen theory was developed to explain the apparent constancy of extinction rates. The theory proposes that continuous evolutionary arms races among species explain the constancy of extinction rates. The Red Queen theory applied to macroevolution is not well supported. The Red Queen theory applied to microevolution is well supported. The theory is now mostly associated with the idea that host–parasite coevolution favours the evolution of sex. Fluctuating fitness epistasis among genetic loci involved in the interaction between a host and its parasites may favour meiotic recombination. Alternatively, recombination is favoured by selective interference among beneficial mutations in finite populations, and host–parasite coevolution maintains this interference.