Some variation is the result of differences in the surroundings, or what an individual does. This is called environmental variation. Humans, dogs and goldfish are examples of species. Different ...

This video explores the principles of evolution by natural selection. The survival and reproduction of individuals best suited to the environment leads to changes in organisms over time. This can be ...

The origin of the Origin / Michael Ruse -- Darwin's analogy between artificial and natural selection in the origin of species / Mark A. Largent -- Variation and inheritance / Robert Olby -- Darwin's ...