Causes and Evidence of Evolution

Objective 3.05: Evidence of the theory of evolution

Causes of Evolution

• Natural Selection• Mutations• Competition• Geographic Isolation

Example of Geographic Isolation• Beetle population divided by a

river.• Both groups of beetles become

different because they adapt to their new (different) environments.

• Even if reunited, they would not mate with each other again because they have evolved genetically and behaviorally into two different species (speciation)!

5 Pieces of Evidence1. Anatomy

2. Embryo Comparison3. Biochemical (DNA)

4. Adaptations5. Fossils

Adaptations• Inherited traits that aid in survival– Mimicry: Acts like another organism or pretends to

be a harmful predator.– Camouflage: Blends in for better survival– Antibiotic/Pesticide Resistance: Some bacteria do

not respond to drugs which means they are able to survive and multiply!

Antibiotic Resistance• Normal H. pylori

bacteria produces an enzyme that activates an antibiotic.

• That mixture creates a “poison” to the bacteria and kills it.

• The bacteria mutates to not produce the enzyme.

Fossils• Evidence of once living organisms.– Can be:1. Bones2. Footprints 3. Imprints

• Fossil Record: The history of life on Earth as shown by fossils preserved in rocks.– Shows:1. How species changed over time2. If any species go extinct

• The Geologic Time Scale is based on the Fossil Record.

Fossils of the Geologic Time Scale

Age of Fossils

• Relative Age: One fossil is older/younger than another based on rock layers.– Does not tell exact age.

Age of Fossils• Absolute Age: The more

exact age of a fossil.– Based on decay of organisms

(Carbon Dating)– Use half life to determine age– Half Life: Time it takes for

half the atoms to decay.