1. Learning objectives How to interpret evolution by Natural selection
What is evolution and where can it happen
What are the conclusions of natural selection
What are the conclusions of biological evolution
What is artificial selection
Where is the REAL debate about evolution

2. Evolution: a cumulative change over time
1928
1947
1990
Ex: Mickey mouse’s evolution

3. 1980s
1990s
2000s

4. Geological Evolution, Astronomical Evolution, Chemical Evolution

5. Geological Evolution, Astronomical Evolution, Chemical Evolution

6. Geological Evolution, Astronomical Evolution, Chemical Evolution
Textbook:

7. “Descent with Modification” or inherited changes
Natural Selection:
“Descent with Modification” or inherited changes
Solutions that work (function) will get passed on more often than “solutions” that don’t work
- These solution or adaptation often will continue to be selected for. Often the “solutions” will become more complex over time. We call these “solution” adaptations
Ex: Eye organs (will see on next slide)
Adaptations are NOT PERFECT but will perform their function to the point that it helps the creature to either
survive or reproduce

9. What Biological Evolution means….
-If you go back far enough into the past, all life shares common ancestry: Hence scientists concluded that life has arisen once on earth. After “forming” evolution by Natural selection eventually it produced the variety of life we see today and in the fossil record
Many refer to this as a “tree of life” and it also has
changed as scientists learn more

10. BIG ideas from Evolution by Natural Selection:
1) The Environment picks the ‘best’ adaptation for any life to
survive or reproduce
ON THE TREE OF LIFE:
2) Tree of life has 1 ‘trunk’ = ALL life shares 1 origin
and life only started 1 time
3a) Less time apart = more similarities = more recent common ancestor
3b)More time apart = more difference = common ancestor in distant past
4)Evolution is not perfect: 99% of all species that have lived have already gone extinct. What is alive today is > 1% of all variation that has ever lived
again evolution is not perfect = those not able to adapt to their environment die and go extinct
5) Earth is far older than people thought in Darwin’s Day

11. BIG ideas from Evolution by Natural Selection:
1) The Environment picks the ‘best’ adaptations for any life to survive or reproduce
ON THE TREE OF LIFE:
2) Tree of life has 1 ‘trunk’ = ALL life shares 1 origin
and life only started 1 time
‘origin’ = start point

12. 3a) Less time apart = 3b) more time apart = ON THE TREE OF LIFE:
more similarities =
more recent common ancestor
3b) more time apart =
more difference =
common ancestor in distant past

13. ON THE TREE OF LIFE: 4)Evolution is not perfect:
99% of all species that have lived have already gone extinct.
What is alive today is > 1% of all variation that has ever lived =
those not able to adapt to their environment die and go extinct
5) Earth is Old: (4.5 billon years)
But in Darwin’s time was thought only a 400,000 -1million years old

14. Darwin’s own notes

17. What Biological Evolution means….
- ALL living things share some form of common ancestry
- the more recent the shared ancestor : the more similar species should be (physically, behaviorally)
Ex:
Present
Past
Deer
Tiger
Lion
Mammalian
Ancestor

18. Try: Ostrich, Toucan, Cassowary
Present
Ex:
Deer
Tiger
Lion
Past
Mammalian
Ancestor
Lions & Tigers shared a common ancestor more recently than either of them do with Deer, hence we expect them to seem more similar since they have had less time to evolve apart from each other
Try: Ostrich, Toucan, Cassowary

19. Ostrich
Present
Past
Ostrich
Cassowary
Toucan
Toucan
Cassowary

20. Natural Selection: The process by which favorable heritable traits become more common, and unfavorable heritable traits become less common in the natural world
Artificial Selection: The intentional breeding for certain traits over others (ex: Dogs, Pigs, horses, cows, corn, grapes...basically all modern livestock, crops or pets have been selected for in someway)
Przewalski's horse

22. (Felis silvestris lybica)
African Wild Cat
(Felis silvestris lybica)
Red Jungle Fowl
(Gallus gallus)
(Solanum chilense)

23. Speciation: Evolution of 2 species from 1 ancestral species
- Can happen because of geographic isolation (island populations)
Galapagos Islands
South America
Cormorant
- Can happen because of specialization in behavior
Owl (night hunters)
Falcon (day and night hunters)

24. Reproductive Isolation
Geographic Isolation
Behavioral Isolation
Temporal Isolation
SPECIATION
SPECIATION:
Species ‘A’
Species ‘B’
Common
Ancestor

25. Evidence For Evolution by Natural Selection
Evidence Darwin did NOT Know:
Evidence Darwin Knew:
Fossil Record: shows extinctions and that species have changed over long time, he also knew about the Law of Superposition
Fossil Record: he knew nothing about half-life (λ) or how to tell how old the earth really is or exact age of fossils
Embryology: he knew that certain features in embryos were not in the adults (ex: legs on snakes embryos)
Comparative Biochemistry: knew nothing about DNA or genes or proteins or ATP (only knew parents looked similar to kids)
Comparative Anatomy: knew of vestigial organs in creatures and of homologous and analogous structures
How speciation worked: did not know of need for reproductive isolation to make new species, only that the environment pushed the ‘better’ adaptations to help survival and reproduction
Artificial Selection: he knew how people selected for different dogs, horses, pigs, and farm plants

26. THE REAL DEBATE in Evolution by Natural Selection
How fast does evolution occur?
Gradualism vs. Punctuated Equilibrium
Gradualism: The slow gradual change with many transitional forms in the speciation process
Punctuated Equilibrium: slow gradual changes with small rapid periods of evolutionary change. Would expect fewer transitional forms than with gradualism