In a population, a specific gene has two alleles, 'A' and 'a.' Individuals with

genotype 'aa' die in early childhood. Individuals with genotype 'Aa' have a

higher rate of surviving and reproducing than individuals with genotype 'AA.'

This phenomenon is called

Answer: The phenomenon is called heterozygote advantage

Explanation: Heterozygote advantage is a phenomenon whereby a single copy of a recessive allele doesn't result in a disease in a heterozygous individual rather offers an advantage to the carrier (the heterozygous individual). For example, the sickle cell allele does not cause sickle cell disease in the carrier rather confers resistance to malaria in heterozygous individuals, but causes a deadly disease (sickle cell disease) in homozygous individuals.

In a population, a specific gene has two alleles, 'A' and 'a.' Individuals with

genotype 'aa' die in early childhood. Individuals with genotype 'Aa' have a

higher rate of surviving and reproducing than individuals with genotype 'AA.'

This phenomenon is called survival of the fittest, Darwins law which entails the fittest organisms survives while the ones that could not would go into extinction