Final answer:
Environmental changes affect evolution by creating new selective pressures that favor genetic variations contributing to survival and reproduction. Organisms that adapt effectively pass on these traits, which over time may result in significant changes or speciation, while those unable to adapt may become extinct.
Step-by-step explanation:
Environmental changes play a critical role in evolution by natural selection. When the characteristics of habitats alter rapidly, the niches of animals residing in those habitats are also affected, as they might not have the suitable adaptations required. New environmental pressures select for organisms with genetic variations that provide a survival advantage in the new conditions.
For instance, if a new predator enters the environment, prey species with the ability to evade the predator effectively will likely survive and pass on their advantageous traits to their offspring. Over time, this results in a population that is well-adapted to the presence of that predator.
Evolution by natural selection is not always a slow process; rapid environmental changes can exert a strong selective pressure that leads to quick adaptive responses in a population. However, not all species can adapt successfully, and those unable to do so may face extinction.