A mistake in DNA replication before meiosis produces an organism that is better able to outrun predators.
Explanation:
The genetic variation results from the different alleles of a population. The mutation or mistake in DNA replication would cause gene variants which may be beneficial. The variation in the DNA sequence of genome results in variants in small population.
Genetic variation is the cause of natural selection and eventually, evolution takes place with beneficial traits.
It is mentioned in the question that resulting offspring having received the mutant allele could result in better surviving capabilities or phenotypic traits as they are able to outrun predators.
They are like that because they can't always be faulty and may have at least some spark of truth to this theory also as stated earlier a theory in scientific terms is just an observation so it can't really be turned down hence theory.
