THE MAINTENANCE OF SEX BY PARASITISM AND MUTATION ACCUMULATION UNDER EPISTATIC FITNESS FUNCTIONS

The mutation accumulation hypothesis predicts that sex functions to re duce the population mutational load, while the Red Queen hypothesis ho lds that sex is adaptive as a defense against coevolving pathogens. We used computer simulations to examine the combined and separate effect s of selection against deleterious mutations and host-parasite coevolu tion on the spread of a clone into an outcrossing sexual population. T he results suggest that the two processes operating simultaneously may select for sex independent of the exact shape of the function that ma ps mutation number onto host fitness.