One cause and effect relationship within the topic of evolution is the impact of natural selection on the traits of a species. Natural selection, which is the process by which certain traits become more or less common in a population due to their influence on reproductive success, can cause changes in the genetic makeup of a species over time. The cause is the environmental pressures that favor certain traits over others, such as a change in climate or the presence of a new predator. The effect is the evolution of the species to better adapt to these pressures, resulting in new or modified traits that increase the species' chances of survival and reproduction. This process can eventually lead to the development of new species as populations diverge over time.