Darwin’s Theory of Evolution AP Biology. Shaping Darwin’s Theory Carolus Linnaeus – Specialized in taxonomy – Came up with binomial system for naming.

Darwin’s Theory of Evolution

AP Biology

Shaping Darwin’s Theory

• Carolus Linnaeus– Specialized in taxonomy– Came up with binomial system for naming organisms

• Homo sapiens – H. sapiens = human• Escherichia coli – E. coli bacteria

• Georges Cuvier– Studied fossils (paleontology)

• Each deeper layer of rock contains different species• The further away the layer the more dissimilar the fossils

– Catastrophism

• James Hutton– Geological features (mountains, rivers, etc.) are the product of a slow but

continuous process– Gradualism

• Charles Lyell– Uniformitarianism

• Geological processes seen today have not changed throughout Earth’s history … rate of mountain building is constant

• Jean Baptiste Lamarck– Use and Disuse

• Body parts used the most will develop and those that aren’t used will waste away

• Blacksmith big biceps and long neck of giraffes

– Acquired characteristics• Modifications within own lifetime are passed on to offspring• THIS DOES NOT HAPPEN

– Mice tails cut of for 22 generations

• Epigenetics?

• Thomas Malthus– Much of human suffering is due to population

increasing faster than food supplies and other resources allow

Darwin’s Theory of Natural Selection

1) Organisms reproduce others of their kind

2) More offspring are produced in nature than can survive to reproduce

3) There are variations among offspring within a population

4) Some variations are favorable and allow individuals to survive better

5) Organisms that survive better tend to reproduce more frequently

6) Over long periods of time, favorable adaptations are inherited by most of the population

Descent with modification

• All organisms are related through a common ancestor. Diverse modifications, or adaptations, emerged due to various habitats populated by members of the common ancestor. These “new” modifications help fit them to a specific way of life.

Evolutionary Tree of Elephant Family

• Evidence based on:– Fossils– Anatomy– Order of

appearance– Geographical

distribution

Artificial Selection• Humans select the traits they want and breed

those particular organisms to create new variations very quickly

Natural Selection in the Works!• Insecticide-

Resistance in Insects– The ones with the

resistance gene survive and reproduce

• Antibiotic-Resistance in Bacteria– The ones with the

“super-powered” plasmid survive and reproduce

• Drug-Resistant HIV

Evidence for Evolution

•There are 5 main pieces of evidence showing organisms have evolved

Fossil Record

• Shows a tremendous variety of organisms• Organisms come and go• Reconstruct changes of organisms• Infer behaviors (ex: sharp teeth = carnivore)

Morphology• Similar types of body structures• Homologous Structures– Show common ancestry– Example: teeth of a bear and teeth of a dog– Example: arm of a human and flipper of a whale

• Analogous Structure– Common function but not a common anscestor– Example: wings of a bird and wings of butterfly

Biochemical and Molecular

• Same chemical makeup in biomolecules– Carbohydrates (sugars) – C,H,O– Proteins (amino acids) – C,H,O,N,S– Lipids (fats/oils) – C,H,O– Nucleic acids (DNA, RNA) – C,H,O,P

• The more similar the DNA sequence (A,T,G,G’s) or the protein sequence (amino acids), the more recently a common ancestor existed between two organisms

• Similar metabolic processes from humans to bacteria (same chemical reactions such as Glycolysis)

• Process of: DNA RNA protein is the same

Embryology

• Embryos of fish, lizards, turtles, chickens, pig, mice and humans are very similar.

• Embryonic pattern of development seems to be retained in many organisms.

Biogeographical data

• Organisms unique to a certain location that has been isolated for a long time.– Example: Madagascar has a variety of unique

organisms (lemurs)

• Organisms with very similar body plans are found in different areas around the world.– Example: Flightless birds (kiwi, ostrich, rhea, emu,

cassowary)