Fluctuating selection

If this wet period is followed by drought, the dry variety will be selected for and its numbers will increase.

As periods of dryness and wetness fluctuate, so too does selection on dry-preferring and wet-preferring plants.

Under Red Queen dynamics, a species must adapt to shifting selection pressures of the ever-changing biota which constitute its environment or face extinction.

Experiments in Red Queen environments on real and simulated populations have offered strong support for the maintenance of sexual reproduction despite the two-fold cost of sex.

[8][9] Fluctuating selection may also play an important role in host-parasite coevolutionary relationships, specifically in the maintenance of sex.