Lottery model of advantage of sexuality
The lottery model (sometimes also called the best man model) is based on the fact that the area of occurrence of any species is mostly heterogeneous to a greater or lesser degree (Williams 1975). Simultaneously, a more or less random sample of the offspring of various parents ends up in each microhabitat in each generation. The individuals compete together in the microhabitat and only the best of them or, to be more exact, those whose phenotype best corresponds to the properties of the particular microhabitat are successful in the competition and leave offspring. The progeny of asexually reproducing species would probably be very well adapted to some type of microhabitat. Those that end up in some other microhabitat would, however, most probably lose out in competition with the offspring of sexually reproducing parents. Because of their polymorphism, part of the progeny of sexually reproducing organisms would always have properties that would be especially suitable for any type of microhabitat.