Structural adaptations
Structural adaptations are a part of Natural Selection in evolution.Some people call this survival of the fitest. An adaptation is an inherited characteristic that increases any organisms chance of survival. Adaptations would occur in a populaton over time. The more the population is isolated the faster these changes would occur.This would happen because the gene pool wouldn't be very diverse. Charles Darwin noticed this on a very isolated chain of islands off the coast of South America called the Galapagos Islands. He noticed this in the beaks of finches, depending on the enviroment and the source of food the beak would be best adapted to these variables.

external image galapagos-map_2.jpg
(a picture of the Galapagos Islands)

For example a finches that eat cacti would a longer skinnier beak so they don't get poked in the eye, and a finch that eats berries and nuts would have a larger beak to break the shells.

external image galapagos.jpg
(above is a picture of the finches that Darwin observed)