1. Chapter 13: Evolution

2. Evolution
Evolution – the idea that life changes over time (not a theory).
Example: Megalodon jaw compared to a modern Great White jaw.

3. We see life change over time due to selective breeding (by humans)
- Examples: Dogs, Corn

4. African elephant tusk size - poaching
- Down by 50% in last 150 years.
- Elephants with small tusks survive better.

5. History of Theories of Evolution
Roman named Lucretius 1,900 years ago
1809 Jean Baptiste Lamarck
- Suggested that evolution happens because of use or disuse of a structure.
- Acquired traits are passed on
- Example: Giraffe necks

7. 1831 Charles Darwin became Naturalist on the Beagle (a ship).
- 5 year voyage collecting samples of life from different places.
- Others published ideas about evolution, but none could explain HOW it occurs.

9. - Darwin saw that life in different places has different characteristics. – finches
- Fossils of past life are different from present life forms. – giant armadillo

10. Natural Selection
In 1859, Darwin published his book On the Origin of Species by Means of Natural Selection

11. Natural selection has 4 major points:
All populations have variation among individuals.

12. 2) More offspring are created than can survive in the environment
– competition & survival of the fittest

13. 3) Individuals within a population that are better able to survive in their environment are more likely to reproduce.

14. 4) Beneficial traits will increase in a population over time.

15. Evidence for Evolution
Fossils:
Fossil links have been found between fish & amphibians, reptiles & birds, and reptiles & mammals

16. Changes in Proteins and Nucleic Acids:
Proteins and nucleic acids change over time from mutations.
The more amino acid or nucleotide differences, the further separated the species are.

17. Phylogenetic tree – diagram that shows how organisms are related through evolution.

18. Similar anatomy:
Homologous structures – structures that share common ancestry.
- Arm bones of birds, lizards, and mammals have the same structure.

19. Vestigial structures – structures that are of no use today, but show a link to a previous ancestor.
- Tailbones in humans
- Leg bones in snakes
- Pelvic bones in whales

20. Embryology – Embryos show evolutionary similarities that agree with the fossil record and protein or DNA changes.

21. How is a New Species Made?
Divergence - the accumulation of differences between two groups.
Speciation – The two groups can no longer breed and are considered two separate species.

22. Isolation – two populations of a species cannot breed with each other because of location, will cause divergence.

23. Gradualism – many small changes over a long period of time lead to new species.

24. Punctuated equilibrium – periods of rapid change separated by periods of little or no change.
Thought to be caused by major changes in the environment.

25. Extinctions – leave openings in the ecosystem where new organisms can be successful. (food sources, habitats, etc.)

26. Human activities – Humans change the environment and animals adapt.
- Peppered moths changed color after the industrial revolution because the trees they lived on were covered in soot.