Infection, Polymorphism and Evolution

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. SUMMARY In house mice, and probably most mammals, major histocompatibility complex (MH influence both immune recognition and individual odours in an allele-specific fash generally assumed that some form of pathogen-driven balancing selection is res unprecedented genetic diversity of MHC genes, the MHc-based mating preferences mice are sufficient to account for the genetic diversity of MHC genes found in this and These MHC disassortative mating preferences are completely consistent with the conven pathogen-driven MHC heterozygote advantage operates on MHC genes. This is beca preferentially produce MHIc-heterozygours progeny, which could enjoy enhanced d However, such matings could also function to avoid genome-wide inbreeding. To dis these two hypotheses we measured the fitness consequences of both experimentally ma inbreeding and MHC homozygosity and heterozygosity in semi-natural populations of w mice. We were able to measure a fitness decline associated with inbreeding, but wer fitness declines associated with MHC homozygosity. These data suggest that inbreeding the most important function of MHc-based mating preferences and therefore the fund force diversifying MHC genes in species with such mating patterns. Although c conclusion is consistent with the majority of the data from the inbreeding and immun