Originally published as Genetics Published Articles Ahead of Print on August 9, 2008.

Genetics, Vol. 179, 2229-2238, August 2008, Copyright © 2008
doi:10.1534/genetics.107.085563

Cut Thy Neighbor: Cyclic Birth and Death of Recombination Hotspots via Genetic Conflict

Urban Friberg1 and William R. Rice

Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California 93106

1 Corresponding author: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106-9610.
E-mail: friberg{at}lifesci.ucsb.edu

Most recombination takes place in numerous, localized regions called hotspots. However, empirical evidence indicates that nascent hotspots are susceptible to removal due to biased gene conversion, so it is paradoxical that they should be so widespread. Previous modeling work has shown that hotspots can evolve due to genetic drift overpowering their intrinsic disadvantage. Here we synthesize recent theoretical and empirical results to show how natural selection can favor hotspots. We propose that hotspots are part of a cycle of antagonistic coevolution between two tightly linked chromosomal regions: an inducer region that initiates recombination during meiosis by cutting within a nearby region of DNA and the cut region itself, which can evolve to be resistant to cutting. Antagonistic coevolution between inducers and their cut sites is driven by recurrent episodes of Hill–Robertson interference, genetic hitchhiking, and biased gene conversion.