Evolution Chapter 15

The Theory of Evolution Biological diversity Change over time Process by which modern organisms have descended from ancient organisms.

Ideas that Shaped Darwin’s Thinking Believed that the Earth and all its forms of life had been created only a few thousand years ago Since the original creation, neither the planet nor its living species had changed Rocks and major geological features were thought to have been produced suddenly by catastrophic events that humans rarely witnessed

History of Evolution Hutton: Lyell: Layers of rock from very slowly Earth had to be much more than a few thousand years old. Lyell: Principles of Geology Geologic features could be built up or torn down

Lamarck: first scientists to recognize that living things have changed over time. All species were descended from other species 3 parts to theory: Tendency towards perfection Use and disuse Inheritance of acquired traits

Malthus: If the human population continued to grow unchecked, sooner or later there would be insufficient living space and food

Charles Darwin Hypothesis of evolution 1809 H.M.S Beagle Collected fossils and made observations Galapagos Islands Origin of Species

Artificial Selection Nature provided the variation, and humans selected those variation that they found useful Selective breeding; inheritable variation

Evolution by natural selection Struggle for existence: members of each species compete regularly to obtain food, living space, etc. Higher birth rates and shortage of basic needs

Survival of the Fittest the ability of an individual to survive and reproduce in its specific environment Fitness: ability to survive and reproduce in environment Adaptation: inherited characteristic that increases chance of survival Natural Selection

Descent with Modification Each living species has descended, with changes, from other species over time Living organisms are related to one another Common descent: all species were derived from common ancestors

Evidence of Evolution Fossil records: by comparing fossils from older rock layers with fossils from younger layers

Geographic Distribution: similar animals in different locations were the product of different lines of evolutionary descent

Homologous Structures: four-limbed vertebrates have descended from common ancestors.

Similarities in Embryology: early stages of many animals with backbones are very similar