A genetic change that occurs due to the evolutionary process, which consists of modifications in the structure or attributes of an organism, is a

A genetic change that occurs due to the evolutionary process, which consists of modifications in the structure or attributes of an organism, is a mutation.

Mutation is one of the evolutionary processes (fundamental forces of evolution) that together with natural Selection, genetic drift and gene flow can change allele frequencies within a single population. Mutations are the only way to form new alleles in a gene pool.