Most organisms have relatively stable populations, so that, of all those born, only some survive to reproduce. Those that survive do so because they are in some way better suited to their environment. This process involves natural selection by environmental pressures among all of the variations present in a population. Over time, those alleles that enhance survival and/or reproductive success will become more common in the population and the genetic composition of the population will change.
Keywords: Galapagos finches; Darwin; macroevolution; artificial selection; adaption; evolution




