Pathogens, polymorphism, and the evolution of sex

Abstract

For short-lived pathogens, adaptation to one host genotype is negatively correlated with adaptation to others when host genotypes are sufficiently differentiated. This may provide an adaptive basis for sexual recombination, which lowers cross-genotypic correlations among offspring and other kin, and thereby interferes with pathogenic transmission, multiplication, and adaptation. Such pathogen-host interactions lead to generalized frequency-dependent selection for allozymic diversity. The ecological and life-historical correlates of parthenogenesis, inbreeding, chromosome number, and polymorphism are consistent with this hypothesis. © 1982.