Selection can maintain variation within populations in a number of ways. Negative frequency-dependent selection tends to favor rare phenotypes. Oscillating selection favors diff erent phenotypes at...

Selection can maintain variation within populations in a number of ways. Negative frequency-dependent selection tends to favor rare phenotypes. Oscillating selection favors diff erent phenotypes at diff erent times. In some cases, heterozygotes have a selective advantage that may act to retain deleterious alleles.

■ How would genetic variation in a population change if heterozygotes had the lowest fitness?