Simulated emergence of cyclic sexual-asexual reproduction

Motivated by the cyclic pattern of reproductive regimes observed in some sp ecies of green flies ("aphids"), we simulate the evolution of a population enduring harsh seasonal conditions for survival. The reproductive regime of each female is also seasonal in principle and genetically acquired, and ca n mutate for each newborn with some small probability. The results show a s harp transition at a critical value of the survival probability in the wint er, between a reproductive regime in the fall that is predominantly sexual, for low values of this probability, or asexual, for high values. (C) 2001 Elsevier Science B.V. All rights reserved.