The Theory of Evolution

1. The Theory of Evolution

2. Charles Darwin • 19th century English naturalist • developed a theory on how evolution works • studied on the Galapagos Islands because each island had different environments • wrote On the Origin of Species

3. Darwin’s Theory • Species evolve from a common ancestor • Variation – slight difference in an inherited trait of individual members of a species • occurs as a result of mutations during sexual reproduction

4. Natural Selection "Survival of the Fittest” • organisms with variations that help them survive, live longer and are therefore able to reproduce to pass on those variations • ex. tortoises with longer necks will survive longer than tortoises with short necks if the food sources are up high

5. Adaptations • an inherited trait that increases an organism’s chance of surviving and reproducing in its environment

6. 3 Types of Adaptations • Structural – involve physical characteristics • ex. coloration, shape • Behavioral – involves the way an organism acts • ex. hunting at night, moving in herds • Functional – involve internal body systems • ex. hibernation, temperature regulation

7. Environmental Interactions Camouflage Mimicry the resemblance of one species to another species • an adaptation that enables a species to blend in with its environment

8. Evidence of Evolution

9. Comparative Anatomy • the study of similarities and differences among structures of living species • Homologous Structures – body parts of organisms that are similar in structure, but different in function

10. Analogous Structures - body parts that perform a similar function, but differ in structure • ex. bird wings and insect wings

11. Vestigial Structures • body parts that have lost their original function through evolution • shows that the structures served a purpose at one point, but now are no longer needed • ex. cormorant wings, whale pelvic bones

12. Developmental Biology • Embryology – study of embryos from fertilization to birth

13. Molecular Biology • Scientists can use DNA to show how closely related organisms are • Divergence – the point at which an organism breaks away from its common ancestor