4Q Although selection against a recessive lethal gene might be total, the gene is rarely ever completely eliminated from a population. Why?
1. New mutations occur
2. Selection is ineffective
3. A reserve is held in the heterozygotes
4. #1 & #3
5. #2 & #3
CORRECT! In a large population, the gene will appear as a new mutant with a measured frequency each generation. However, as the numbers dwindle, fewer and fewer heterozygotes are around to produce strong probabilities of homozygous recessives arising. Hence, the gene remains "hidden" in the heterozygotes that do remain in the population.