genetic drift
Evolution Curriculum from BioGraph
Evolution is a change in genetic information in a population that is observed over many generations. Two important factors contribute to evolution:
genetic drift - a process by which the genetic traits in a population change due to the random chance survival and reproduction of particular individuals; and
natural selection - a process by which individuals with certain genetic traits are more likely to survive and pass on those traits to their offspring, making those traits more common in the population.