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Evolution of MHC genetic diversity: a tale of incest, pestilence and sexual preference
1Center for Mammalian Genetics, University of Florida, Gainesville 32610-0275.
Abstract:
Evidence from the house mouse (Mus) suggests that the extreme diversity of genes of the major histocompatibility complex (MHC) results from three different forms of selection involving infectious disease (pestilence), inbreeding (incest) and MHC-based mating (sexual) preferences. MHC-based disassortative mating preferences are presumed to have evolved because they reduce homozygosity throughout the genome, and particularly within loci linked to the MHC. Progeny derived from such disassortative matings would enjoy increased fitness because of both reduced levels of inbreeding depression and increased resistance to infectious disease arising from their increased MHC heterozygosity.
Insights
Major histocompatibility complex (MHC) gene diversity in mice arises from selection related to disease, inbreeding, and mating preferences. These MHC preferences promote offspring fitness by reducing inbreeding and increasing disease resistance through genetic diversity.
Area of Science:
- Evolutionary biology
- Immunogenetics
- Behavioral ecology
Background:
- The major histocompatibility complex (MHC) exhibits extreme genetic diversity.
- This diversity is hypothesized to be driven by various selective pressures.
Purpose of the Study:
- To investigate the evolutionary forces shaping MHC gene diversity in the house mouse (Mus).
- To explore the roles of infectious disease, inbreeding avoidance, and mating preferences in MHC evolution.
Main Methods:
- Analysis of evidence from house mouse populations.
- Examination of genetic diversity patterns in relation to selective pressures.
Main Results:
- MHC diversity is influenced by selection pressures from pestilence, incest avoidance, and sexual selection based on MHC type.
- MHC-based disassortative mating preferences reduce genomic homozygosity, particularly at MHC-linked loci.
Conclusions:
- MHC-based mating preferences enhance offspring fitness by mitigating inbreeding depression.
- Increased MHC heterozygosity in offspring improves resistance to infectious diseases.