Final answer:
New genetic diversity is added to a population through mutations and sexual reproduction, which create new alleles and unique combinations of genetic information respectively.
Step-by-step explanation:
The only way that new genetic diversity can be added into a population is through mutation and sexual reproduction. Mutation refers to a permanent change in the DNA sequence, which is the ultimate source of new genetic variation in any population. These genetic changes can affect an individual's traits and are the basis for evolutionary processes. Sexual reproduction also contributes to genetic diversity; it combines genetic information from two parents to produce offspring with unique combinations of alleles, thus increasing the variation within a population. Additionally, new traits can be introduced via gene flow, when individuals with different alleles migrate into a population.