A theory of mate choice based on heterozygosity

In theories of mate choice that rely on genetic benefits, the nature of the ''good genes'' involved has received little attention. A review of genetic studies of mate choice in a variety of species and situations suggests that individual heterozygosity is more important than previously realized. Females are predicted to value heterozygosity in their offspring and under some conditions in their males. The expression of vigor, condition-sensitive ornaments, and symmetry in males may be a direct reflection not of ''good genes'' but of individual heterozygosity at key loci or at many loci. Like sexuality itself, mate choice based on heterozygosity and genic diversity may be an adaptation that favors the production of diverse and superior competitors. Female choice is made meaningful by sexuality and the adaptive value of choice probably depends on some of the same factors that maintain sexuality.