Evolution is the changes that take place within a species' genetic makeup from generation to generation. While mutations are changes that happen to the direct offspring, evolution is a gradual process and is usually the result of trying to adapt to one's environment, food supply, or other factors.
Even the term evolution is surrounded in controversy as many religious conservatives base its definition on theories from Charles Darwin and other biologists that seemed to conflict with religious doctrines, namely that humans and higher primates once shared a common ancestor, but that is not the only function of the term. Evolution in and of itself is simply the recordable, observable changes in a species, and is not solely connected to any single school of thought or religion.
One of Darwin's less controversial theories that accurately depicts evolution is survival of the fittest, or the understanding that only the individual organisms within a population that are well-suited to the environment and its conditions will survive; once only those strongest and best-suited individuals remain, their offspring will continue to develop and show traits for this adaptation.
A number of species have changed color to adapt to their surroundings. The peppered moth is called that because this once-white species was easy to spot by predators when it landed against the soot- covered buildings of industrial London. The moth developed a mottled pattern that made it harder to see. Another example is the deer mouse, whose dark-colored fur helps it blend into its forest habitat, but generations of deer mice that moved to the sandy foothills developed a lighter coat for camouflage.
Over time, features that a species once exhibited but no longer needs can shrink or disappear. This is seen in animals that live in caves. There are a number of species-fish, insects, crabs, lizards, and more-that live in the perpetual blackness of a cave environment. Many of these species have lost their pigmentation since they don't need to hide from predators and since potential mates cannot see and be attracted to their coloring. Other species, like the Mexican cave fish, even lost their eyes as the need for sight was gone.
3. Diet and Nutrition
Italian Wall Lizards are an example of a species that was purposely introduced into a foreign environment to see what adaptations the species developed. These lizards had to learn to subsist on more vegetation and less insects, so they not only developed a larger head with a better bite for breaking off and repetitive chewing of vegetation, but they also developed a new adaptation in their digestive systems that allowed bacteria more time to break down the plant matter during digestion.
Another lizard species, the Three-Toed Skink, evolved in how it reproduces. While lizards are reptiles and therefore lay eggs, the populations in more temperate climates continue to lay eggs while lizards in colder regions can give birth to live young, essentially keeping their eggs inside of their bodies to prevent freezing.