Sex and adaptation in a changing environment

In this study we consider a mathematical model of a sexual population that lives in a changing environment. We find that a low rate of environmental c hange can produce a very large increase in genetic variability. This may he lp to explain the high levels of heritability observed in many natural popu lations. We also study asexuality and find that a modest rate of environmen tal change can be very damaging to an asexual population, while leaving a s exual population virtually unscathed. Furthermore, in a changing environmen t, the advantages of sexuality over asexuality can be much greater than sug gested by most previous studies. Our analysis applies in the case of very l arge populations, where stochastic forces may be neglected.