Genetic variation is the difference in the sequence of DNA in the individuals of a population and a heterozygote has more genetic variation that homozygote person because heterozygote has two different alleles of a gene while homozygous individual have two same alleles.
Heterozygotes have advantage over homozygotes because it protects the individual from many genetical diseases and increase the genetic variation by increasing the gene pool in the population. So higher fitness results in more genetic variation in the population therefore the statement is false.
