On the evolution of an optimal rate of sexual reproduction.

A model of seasonal selection acting on a prime locus with a modifier locus that determines the sexuality rate of the individual has been proposed. A fluctuating environment was assumed, such that in each generation some catastrophe may occur, in which case the only individuals that survive carry an allele resistant to the current catastrophe on the prime locus and the other individuals are most likely exterminated. Under such selection pressure, the proportion of the whole population that is exterminated depends on the number of possible catastrophes. For 3 catastrophes, possibly 1/2-2/3 but no more of the population may die. The authors investigated how this process affects the modifier locus that determines the sexuality rate where, for some tau a tau -sexual individual is one that produces a proportion tau of its descendants sexually and the rest asexually.-Authors