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Evolution: The change in species over time Charles Darwin: Theory of Natural Selection

Evolution Biodiversity

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Page 1: Evolution Biodiversity

Evolution: The change in species over time

Charles Darwin: Theory of Natural Selection

Page 2: Evolution Biodiversity

Theory of Natural Selection

• Overproduction of offspring: species produce far more offspring than are needed.

• Competition: space and food are limited so competition occurs for resources. Only fraction can survive

• Variation among offspring: individuals in a species vary and these are inheritable

Page 3: Evolution Biodiversity

Theory of Natural Selection

• Struggle for survival: result of competiton

• Adaptations due to variations, some individuals are better adapted to survive and reproduce.

• Natural Selection: environmental factors will select the optimal traits. The “best fit” will survive and reproduce.

• Speciation: Over many generations, favorable adaptations accumulate and many changes lead to new species.

Page 4: Evolution Biodiversity

What is the source of Variation?

Mutations: Changes in the DNA

Sexual Reproduction: Recombination of chromosomes

Page 5: Evolution Biodiversity

Why is variation important to evolution?

Variations within a species increases the chance of survival when conditions change.

cichlid fish

Page 6: Evolution Biodiversity

Fossil Evidence shows Evolutions progresses without set direction. What does it indicate when branches end?

Page 7: Evolution Biodiversity

How should the finches at the top compare to each other? Why?

Page 8: Evolution Biodiversity

Observed Natural Selection

• Insect resistance to insecticides

• Bacterial resistance to antibiotics

Explain how this occurs?

Variation (mutation)

Environmental factor (pesticide)

Reproductive success

Survival of Fittest

Population changes

Page 9: Evolution Biodiversity

How do we determine which organisms are more closely related?

•Compare anatomy

•Compare development

•Compare biochemistry

•Compare cells

Similarity implies relationship!

Page 10: Evolution Biodiversity

Homologous structures are a clues to determine evolutionary relationships.

What could be the reason for similarity in structure?

Page 11: Evolution Biodiversity

Molecular data is the best way to compare organisms to relatedness. Compare genes, proteins,

Which animal is most and least related to the human?