The Red Queen and the Timescale of Antagonistic Coevolution: Parasite Selection for Genetic Diversity

The Red Queen model of antagonistic coevolution has been the preferred explanation for certain biological phenomena, such as extreme genetic diversity and trans-species polymorphisms in disease genes. This model has been studied on diverse timescales using direct observations (covering days to a few years), archived material (several decades), postglacial processes (about 10,000 years), and phylogeographic and phylogenetic methods (millions of years). Here, I review the evidence for specific antagonistic coevolution in the host-parasite Daphnia-Pasteuria model system, paying particular attention to the timescales addressed by different approaches. Microevolutionary studies of the coevolutionary process are congruent with macroevolutionary patterns observed in phylogeographic contexts and deep time. This evidence strongly supports the Red Queen model, providing a powerful explanation for the extraordinary genetic diversity seen in host and parasite disease genes.