The Evolution of Mating Preferences and Major Histocompatibility Complex Genes

Area of Science:

• Evolutionary biology
• Immunogenetics
• Behavioral ecology

Background:

• Mating preferences for genetically dissimilar partners at the Major Histocompatibility Complex (MHC) are observed in various species, including mice.
• The highly polymorphic MHC genes are crucial for immune self/nonself recognition, suggesting a link between mating behavior and offspring immunocompetence.
• Despite observed preferences, the evidence and evolutionary functions of MHC-dependent mating remain debated.

Purpose of the Study:

• To critically review existing studies on MHC-dependent mating preferences in mice, sheep, and humans.
• To explore the adaptive hypotheses and potential functions of MHC-driven mating behaviors.
• To synthesize evidence supporting the role of MHC in mate choice and its implications for offspring fitness.

Main Methods:

• Comprehensive literature review of studies investigating MHC-dependent mating preferences across species.
• Analysis of adaptive hypotheses including MHC heterozygote advantage, Red Queen hypothesis, and kin recognition.
• Synthesis of evidence from behavioral, genetic, and immunological studies.

Main Results:

• MHC-disassortative mating can lead to MHC-heterozygous offspring with potentially enhanced immunocompetence against multiple parasites.
• MHC-dependent mating may function as a 'moving target' strategy against rapidly evolving parasites, driving MHC diversity.
• MHC genes may also play a role in kin recognition, thus avoiding inbreeding through mate choice.

Conclusions:

• MHC-dependent mating preferences are supported by evidence and likely serve adaptive functions related to parasite resistance and immune diversity.
• The Red Queen hypothesis and heterozygote advantage provide strong frameworks for understanding MHC-driven mate choice and MHC polymorphism.
• Avoiding inbreeding through kin recognition is another plausible function of MHC-influenced mating preferences.