Sexual reproduction and viability of future offspring.

For some natural range of parameters, the viability of sexually produced individuals at equilibrium is never higher on the average than that of asexually produced individuals. In all cases, average viabilities of the 2 subgroups (sexually and asexually produced individuals) are not much different from each other. That is true even if the cost of sex is quite high. The maintenance of sex is then explained, however, on the grounds of a crucial advantage in average fertility of grandoffspring born (either sexually or asexually) to a sexually produced offspring over that of grandoffspring born to an asexually produced offspring, a factor that is less apparent to empirical observations. In the present model even if the unbeatable strategy of reproduction is full sexuality, father-offspring and grandfather-grandoffspring correlations remain positive. Hence, both sexual reproduction and sexual preference of the fit can evolve and be maintained simultaneously.-from Authors