Evidence for Evolution

1. Evidence for Evolution

2. Evolution Support • Fossil Record • Allow us to see the similarities between ancient creatures and modern creatures • Transitional fossils • Show the transitional stages of evolution • Example ----------

3. Fossil Evidence cont • Derived traits • Newly evolved traits features (such as feathers) that do not appear in the fossils of common ancestors • Ancestral traits • More primitive features such as teeth and tails that do appear in ancestral forms

4. Comparative Anatomy • Homologous structures • Anatomically similar structures inherited from a common ancestor • The theory of evolution predicts that body parts are more likely to be modifications of ancestral body parts then entirely new features.

6. Comparative Anatomy • Vestigial structures • Structures that are reduced forms of functional structures. Usually are no longer necessary • Nictitating membrane • Third, usually transparent, eyelid that moves horizontally across the eye.

7. Comparative Embryology

9. Comparative Biochemistry • Important Enzymes and other chemicals that are used by the body remain relatively unchanged

10. A classic experiment took a mouse Pax6 gene and turned it on in a fly's legs. The result? A fly with eyes on its legs. Even though the triggering gene (Pax6) was from a mouse, the eyes that the fly developed on its legs were those of a fly. That's because only the on/off switch (Pax6) was from a mouse; all the genes controlled by it were from a fly. Nevertheless, when the mouse gene said "build an eye," the fly's body understood those directions perfectly, since they both communicate in the same genetic language. These eye-building genes from different animals are so similar that they seem to be interchangeable. In fact, a mouse's or a fly's eye-building gene would probably work just fine in you!

11. Geographic Distribution • Darwin's observation • Mara occupies a niche in South America similar to the rabbit in Europe. • The Mara is more similar to other South American animals then to the rabbit

12. Adaptation • Change in a species to make it more fit for its environment • Fitness: How much of a contribution does a new trait make to the survival of an organism • A trait shaped by natural selection • Better adapted = better chance of mating

13. Camouflage • Some species have evolved morphological adaptation that allows them to blend in with their environment

14. Mimicry • One species evolves to resemble another species • Usually occurs in harmless species to look like a dangerous species