INTRODUCTION TO EVOLUTION

AP BIOLOGY

MR. ORNDORFF

FEB. 2004

Special Creation vs. Evolution

• Species distinct and created separately by a divine being.

• Earth is thousands of years old. Humans present at original creation.

• Must be accepted on faith (religion).

• Species are all related through “descent with modification.”

• Earth is billions of years old. Humans appeared late in earth’s history.

• Must be testable and supported with evidence (science).

Microevolution vs. macroevolution

• Small-scale evolution (change within a species).

• Examples:– Darwin’s Finches

– Pesticide resistant insects

• Grand-scale evolution (mass extinction and creation of new species)

• Examples:– Eu- from prokaryotes

– Extinction of dinosaurs

– Adaptive radiation of mammals

Evidence for macroevolution

• Biogeography (no placental mammals in Australia).

• Fossil Record (vertebrate skeletons) (Whale Fossils-http://www.pbs.org/wgbh/evolution/library/11/2/e_s_3.html)

• Comparative anatomy (homologous structures and vestigial organs).

• Comparative embryology. (Embryology Film Clip- http://www.pbs.org/wgbh/evolution/library/04/2/quicktime/l_042_02.html)

• Molecular biology (DNA and proteins).

Fossil formation (Fig. 22.2)

Homologous structures (Fig. 22.9)

Molecular data and vertebrate evolution (Fig. 22.11)

Mechanisms for Evolution

Lamarck (1744-1829)• Organisms “feel a

need” to adapt.• Use and disuse idea

(e.g. blacksmith biceps and giraffe neck).

• Inheritance of acquired characteristics theory.

Darwin (1809-1882)• Individuals vary (e.g.

pigeons and dogs).• Like tends to beget like.• Limited resources allow

few offspring to survive.• Theory of natural

selection.

Subtleties of Natural Selection

• Individual organisms do not evolve. A population is the smallest unit that evolves.

• Natural selection acts only on hereditable variations (i.e. genetically controlled traits).

• Natural selection acts differently as environmental factors vary from place to place and time to time.

Natural selection in action (Fig. 22.7)