1. Theory of Natural Selection:
Darwin’s explanation for HOW evolution works.

2. VOYAGE OF THE HMS BEAGLE : 1831 - 1836

3. 7 Steps to Natural Selection
Overpopulation (overproduction)- animals produce more offspring than survive.
Variation- animals of the same species are different
Change in environment-
a) Biological - food, predators, shelter, etc.
b) Physical…water, oxygen, temp, etc.
4. Struggle for existence- competition for water, food, & shelter
5. Survival of the fittest- the best adapted & strongest tend to survive longer & produce more offspring
6. Inheritance- favored/best fit/selected variations (characteristics) are passed on to offspring.
7. New species arise- “selected” individuals grow in number and become a new species that cannot reproduce with original species

5. Darwin’s Observation: 13 or so species of finches on different Galapagos islands; these finches resembled the South American (mainland) finches more than say finches in Asia….

7. Same process for other species!

8. Jean Baptiste Lamarck: the outcaste!
used the fossil record as evidence
proposed a theory of evolution where organisms became better and better
Mechanism - ”use” and “disuse” leads to:
inheritance of acquired characteristics (you ‘acquire’ a phenotype in your lifetime and pass it on to your kids)
also means environmental influences can be inherited
DON’T BE LAMARCKIAN!

10. Hugo DeVries & Mutation Theory
New Characteristics suddenly appear
Mutation
These can be passed on and may or may not help a species become more fit
Helped to modify Darwin’s Theory

11. Evidences for Darwin’s theory
Fossil record - horse lab
Homologous Structures
Vestigial structures
Artificial selection

12. Natural selection in action: the evolution of insecticide-resistance occurs in nature - individuals with the best fit genes that can resist the insecticide will survive….
Fig

13. B) HOMOLOGIES –
Similarities in characteristics resulting from common ancestry is known as homology.
1) Homologous Structures: Same skeletal elements, but different functions

14. Human hand, cat limb, whale flipper, bat wing - they all have the same basic bone structure and design; So they have ALL evolved from a common ancestor with a similar ‘limb design’.
B) HOMOLOGIES –
HOMOLOGOUS STRUCTURES

15. Some Alleged Vestigial Organs in Man
C) Vestigial organs, structures that are not used, but which had important functions in ancestors - still retained in descendents, so evolution/change has occurred.
Some Alleged Vestigial Organs in Man
Tonsils
Adenoids
Coccyx (tail bone)
Nictitating membrane of eye
Thymus
Appendix
Little toe
Wisdom teeth
Nipples on males
Parathyroid
Nodes on ears "Darwin's points"
Ear muscles for wiggling
Pineal gland
Body hair

16. C) Vestigial organs – spurs in snakes, hind leg bones in whales.

17. Artificial Selection

18. Artificial Selection: The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.
Short period of time needed for Artificial Selection

19. Heredity: Characteristics that are passed down to offspring
Mutations: Changes that occur in the hereditary material
Mutant: The new form that survives a mutation and passes this trait on to offspring
Adaptation: A favorable variation within a species that may help an organism survive

20. Natural selection - Predators/famine/space shortage/disease/ environmental changes

21. Origin of life and Stanley Miller’s Experiment

22. Abiotic synthesis of organic monomers
Stanely Miller - simulated conditions on early Earth (no oxygen, reducing environment with inorganic gases like H2, CO2, NH3, CH4; lightning/UV with no ozone. Favored the synthesis of organic compounds from inorganicmaterial
The Miller-Urey experiments produced a variety of amino acids and other organic molecules (monomers).