Carrying capacity, competition and maintenance of sexuality

A modification of the logistic equation is critically analysed and its appl ication to competition between sexual and asexual populations presented. Su ch a model of competition can be a formal representation of the tangled ban k hypothesis of the evolution and maintenance of sexuality. It shows that t he elimination of asexual individuals by sexual ones is possible only if th e size of the habitat or the width of the ecological niche of sexual indivi duals is twice as large as that of asexual ones. Go-existence of these two forms is theoretically possible under much less rigid conditions. Neverthel ess, such co-existence does not imply that the ecological cost of the elimi nation of asexual individuals by sexual ones is lower than the commonly acc epted biological cost of such elimination.