Question

What does it mean to say that an allele is "fixed" in the population?

Answer 1

Alleles are the individual genes that give rise to certain characteristics in an organism.

When an allele is "fixed" to a population, this means that the characteristic will be constant & most likely will not change until the environment changes as well.

Like with arctic hare, the alleles that influence the color of their coats (white in the winter & brown in the spring/summer) will stay because any fur pattern other than the aforementioned characteristics with result in becoming someone else's food with the lack of camouflage.

Hope that helps!