Selective Breeding – the purposeful breeding of plants and animals for specific traits. Evolution – gradual changes in a species over time, that leads to the development of new species. Competition – struggle for survival between members of the same species, as well as between different species. Homologous Structures – similar body structures that related species inherited from a common ancestor. Examples include the flipper of the dolphin, wing of the bird, and leg of the dog. Mutation – a change in the DNA that is usually bad, but at times can be beneficial or indifferent. Evolutionary Branching Tree – a diagram that shows how species are related, and their common ancestors. Lamarck – put forth the theory that organisms adapt to fit into their environment. Example – the giraffe’s neck. Darwin said that organisms are already changed to fit into their environments. Lucy – is an ancestor of modern humans.