 Solution

Natural selection requires variation among individuals, heritable contributions to that variation, and differences in reproductive success associated with it. Given those conditions, variant frequencies can change across generations. Competition and finite resources help make reproductive success unequal, but selection does not require every interaction to be direct combat. Mutation and recombination supply variation; they do not generally arise because an organism needs a particular adaptation. Drift also changes frequencies, and common ancestry and branching descent connect population changes to the evolution of species. Selection is a mechanism within evolution, not a synonym for every evolutionary change.^[ref]