Darwin called this descent with modification.
Evolution refers to gradual changes over time in a population of organisms.
NOT changes in individual organisms Shift in allelic frequencies. DNA has groups of nucleotides arranged in genes. Gene pool is all the alleles of all genes in a population at a given time, so evolution is the change in allelic frequencies in a gene pool over time . The first time a bacterial culture faces an antibiotic, a few bacteria will survive. The nonresistant bacteria die.