1. Chapter 8B
Biological Evolution

2. Jean Lamarck Theory of need Theory of use and disuse
Theory of inheritance of acquired characteristics

3. Analysis of Lamarck’s Theory
Basic problem: passing on acquired characteristics to future generations

4. The Origin of Species by Means of Natural Selection (1859)
Charles Darwin
Theory of natural selection
The Origin of Species by Means of Natural Selection
(1859)

5. Artificial Selection
Vs.
Natural Selection

6. Descent with Modification
Proposed that all living things descended from a single common ancestor

7. Survival of the Fittest
peppered moth

8. Analysis of Darwin’s Theory
There is not always overpopulation.

9. Analysis of Darwin’s Theory
The “fittest” do not always survive and reproduce.

10. Analysis of Darwin’s Theory
An organism must have the gene for a certain characteristic in order for it to be produced.

11. Analysis of Darwin’s Theory
The theory does not allow for the formation of new characteristics. It only selects for already existing traits.

12. Analysis of Darwin’s Theory
Natural selection regroups existing characteristics.
No new genetic information is created.

13. Later Developments in Evolutionary Theory

14. Species and Varieties, Their Origin by Mutation
Hugo De Vries
Species and Varieties, Their Origin by Mutation

15. Mutation-Selection Theory (Neo-Darwinism)
Blending of Darwin’s theory of natural selection & De Vries’ theory of mutations
Mutations supply the variations, and natural selection determines which variations survive.

16. Mutation-Selection Theory (Neo-Darwinism)
For evolution to occur, new genes must form.
Mutations are the only known way for this to happen.
However, mutations have not been shown to increase the amount of genetic information.

17. Problems with the Mutation Theory of Evolution
Mutations are random.
Scientists cannot control or predict which genes mutations will affect.

18. Problems with the Mutation Theory of Evolution
Mutations are rare.
It is estimated that uncorrected mutations occur once in 10 million cell divisions.

19. Problems with the Mutation Theory of Evolution
To be passed on, mutations must occur in the germ cells.
Mutations in somatic cells will not affect the organism’s offspring.

20. Problems with the Mutation Theory of Evolution
Requires “good mutations”
Must be beneficial
Mutations are either neutral or harmful.

21. Problems with the Mutation Theory of Evolution
Requires “good mutations” happening repeatedly
In many, many organisms all over the world
Not just unlikely impossible!

22. Problems with the Mutation Theory of Evolution
Too many mutations will kill an organism.
Genetic load

23. Problems with the Mutation Theory of Evolution
The mutation theory of evolution is statistically impossible.
Mathematicians have proved that it could not have occurred, even given billions of years.

24. Problems with the Mutation Theory of Evolution
What about the missing links?

25. Punctuated Equilibrium Stephen Jay Gould
The view that evolution occurred in periods or leaps of time, while at other times, no or very little evolution took place