Final answer:
Evolution is the change in inherited traits of a population from one generation to the next, caused by changes in the genetic composition that are passed down through reproductive mechanisms.
Step-by-step explanation:
Any change in the inherited traits of a population that occurs from one generation to the next is known as evolution. These inherited traits are features that are passed down through reproductive means, and they are distinct from acquired traits that an organism may develop over its lifetime. Evolution can occur through natural selection, wherein those traits that confer an advantage for survival and reproduction are more likely to be passed on to subsequent generations.
In the process of evolution, changes in the population's gene pool—a collection of all the gene variants in a species—can happen via asexual or sexual reproduction. For traits to pass on through sexual reproduction, they must be present in the gametes, such as sperm or egg cells. Thus, only heritable traits can evolve over generations, affecting a population over time. This genetic change underlies the observable changes in the characteristics or phenotypes of a population.