1. Evolution and Natural Selection

2. I. What is evolution?
Evolution is any change in the genes of a population over time
Examples:
1. Antibiotic resistance in bacteria
2. Loss of legs by snakes and whales

3. II. Different theories of how the world became as it is today
Big Bang – explosion of a mass of matter to create the universe (solar system ~ 4.6 billion years old)
Creationism – Everything created by a divine being
Spontaneous generation – life “just appears”

4. II. Different theories of how the world became as it is today
Abiogenic molecular evolution
1. Organic molecules gradually assembled from inorganic elements
2. Haldane’s belief
a. “Hot dilute soup” – Earth’s primitive atmosphere had H2O, CO2, ammonia (NH3)
b. Organic molecules formed with energy from UV radiation

5. II. Different theories of how the world became as it is today
3. Oparin’s belief
a. Energy from the sun, lightning, and volcanic heat formed organic
molecules

7. II. Different theories of how the world became as it is today
Evolution – gradualism – SLOW change over time
1. First life was probably a “protocell”
a. membrane bound cell that reproduced
b. Heterotrophic (photosynthesis came later)
c. Prokaryotic – early bacteria
2. Probably happened 4 billion years BP (before
the present)
3. Life may have originated more than once!

8. III. History of Evolutionary Theory
Jean Baptiste de Lamarck – French biologist
1. First to notice that fossils were remains of
past life
2. Lamarckism, or The Theory of Use and Disuse
a. organisms acquire adaptations during their lifetime and pass them on to their offspring

9. III. History of Evolutionary Theory
b. examples of Lamarckism:
1. Snakes lost legs to move well in dense vegetation
2. Giraffes developed long necks from stretching
3. Any change would be passed on to their offspring
3. This theory was later disproved by genetics

10. III. History of Evolutionary Theory
Charles Darwin – English naturalist
1. Life history
a. expelled from medical school, not a good student
b. 22 years old, became a naturalist for the
H.M.S. Beagle
c. (almost wasn’t accepted, captain didn’t like the shape of Darwin’s nose)

11. III. History of Evolutionary Theory
d. made extensive collections of flora/fauna on his 5 year journey
e. spent time in Galapagos Islands – noticed different organisms
f. published The Origin of Species

13. The most famous birds in the Galapagos are Darwin’s finches.
It is believed that a pair of finches were blown to the Galapagos Islands where there were no finches before.
These birds reproduced quickly with lots of food and no natural predators.
They began to compete with each other for food, so they adapted to eat other things.

14. The different beaks allow for better feeding of different foods.

15. Now, there are 14 species of finches in the Galapagos.

16. III. History of Evolutionary Theory
2. Developed the theory of Natural Selection – survival of the fittest
a. all organisms show variation
b. more offspring are produced than can survive
c. struggle for survival (to meet basic needs)
d. some have a better chance for survival
e. survival of the fittest
f. new species originate as they change

17. III. History of Evolutionary Theory
3. Darwin believed that genes of parents blend in the offspring
a. Gregor Mendel’s studies in genetics proved this correct

19. V. Example of Natural Selection
Microevolution – change of gene frequencies in one population
Peppered moth in England
1. Industrial melanism (change in color caused by humans)
2. Moths were originally white or peppered gray
3. Industrial revolution caused pollution
4. Soot covered trees, causing them to be darker
5. Birds saw and ate light moths on dark trees
6. Dark “mutations” of the moth could blend in and survive
7. Population shifted to the dark version of the moth

20. Peppered Moth The moth in its The moth soot covered
natural environment
The moth soot covered
environment
If you were
a bird, which
would you see
and eat first?

21. Processes of Evolution/Speciation
What is a species? A groups of organisms that breed and produce offspring able to reproduce.
What is Speciation? The development of new species from and existing species.
How do/did species develop?
Reproductive isolation
1. Groups of same species can not contact each other
2. Adapt to separate environments
3. Develop into different species

22. VI. Speciation
Allopatric speciation/geographic isolatation – complete geographic isolation of populations
( ex: Squirels and the Grand Canyon)

23. VI. Speciation Adaptive radiation
1. One common ancestor develops into different species based on competition, location, food supply
2. Example: Darwin’s finches

24. VI. Speciation Punctuated Equilibrium – Eldredge and Gould
1. Macroevolution – large evolutionary changes
2. New species suddenly emerge
3. Species change little, become extinct
4. Explains the gaps in the fossil record

25. VI. Speciation E. Gradualism- Gradual, slow change over time
with intermediate organisms found.
Present day
Present day
Common Ancestor

26. Gradualism
Punctuated Equilibrium

27. IV. Support for the theory of evolution
Fossil Record
Sequence of fossil types
1. Fossils – evidence of past life (bones, teeth,
shells, imprints, coprolites)
2. Rocks are formed in layers – older rocks are
deeper
3. Fossils in old layers are older and more simple

29. Support for the theory of evolution
Comparative Anatomy
Vestigial organs – have no CURRENT function
1. Appendix
2. Wisdom teeth
3. Wings on flightless birds
4. Little toe

31. IV. Support for the theory of evolution
Homologous Structures
1. Same structures, but different functions
2. Shows origin in a common ancestor
3. Vertebrate pentadactyl limb
a. human arm
b. horse leg
c. bird wing (on next slide)
d. whale flipper
e. bat wing

34. Comparison of Homologous
organs
Directions: Color each part of
the human arm a different color.
(All bones of the wrist should
be a single color, the bone groups
of the hand should be a single
color. Note the patterns in the
bones.) Then, color the
corresponding bone in each of
the other animals the same
color as the human bone.
(see enlargement for HW)

35. IV. Support for the theory of evolution
Embryological Development
1. Organisms go through similar development
2. Humans had gill slits, tail, fine covering of hair

38. IV. Support for the theory of evolution
Agricultural/Animal Domestication
1. Selective breeding (pets, farm animals, crops)
2. Each generation is not the same

39. IV. Support for the theory of evolution
Competition for Existence/Natural Selection
1. More animals produced than could ever survive
2. Compete for food, water, shelter, mates
( Already discussed)

40. IV. Support for the theory of evolution
Genetics
1. Genetic variation supplies the materials for
natural selection
2. Comparing DNA, RNA, and Protein sequences
3. Recording and comparing inheritance of a trait
(pedigrees)

41. IV. Support for the theory of evolution
DeVrie’s Theory of Mutations
1. Change is caused by
mutations

44. Which two are most similar? Why do you think they are the most similar?
How does this show evidence for change?
What is Comparative Anatomy? ( use your book)
Comparison of Homologous organs
be a single color, the bone groups
the human arm a different color.
What similarities do you see?
Directions: Color each part of
of the hand should be a single
(All bones of the wrist should
color. Note the patterns in the
corresponding bone in each of
the other animals the same
bones.) Then, color the
color as the human bone.