Answer:
Evolution
Step-by-step explanation:
When natural selection occurs, more environmentally favorable traits are being passed on to offspring. As time goes by, more members of the population possess this trait until it's widespread amongst the species. This can even lead to speciation, the creation of a new species. This could also be the answer to your question. This process describes evolution, the process in which favorable and heritable traits are passed on throughout the generations and change the makeup of the species.