Question

Natural selection and genetic drift cannot both operate at the same time in the same population on the same locus. True or False

Answer 1

Answer) False, natural selection, and genetic drift can operate at the same time in the same population.

Both natural selection and genetic drift are mechanisms for evolution (they both change allele frequencies over time). The key distinction is that in genetic drift allele frequencies change by chance, whereas in natural selection allele frequencies change by differential reproductive success.
If the frequencies of traits in a population change purely by chance, then genetic drift has occurred. This may happen when a random subset of a population dies (i.e., from a natural disaster or from indiscriminate human hunting). The remaining individuals are left to pass their traits to later generations, but the population has changed, so evolution has occurred.