1. The process by which species have changed over time
EVOLUTION
The process by which species have changed over time
Supporting Observations indicate certain organisms may have a common ancestor, not that one organism changed into another

3. Supporting Observations
Fossils: the preserved remains of ancient organisms
Examples of Fossils
Imprints in sedimentary rocks
Organisms preserved in amber, ice, tar
Petrified shells or bones

5. Fossil Sequence
It is assumed that the lower layers are older than upper layers
The fossils found in the lower layers are simpler while those in the upper layers are more complex, but resemble the more primitive forms

6. Comparative Cytology
The cell is the unifying structure for al living things
Organelles are the same in structure and function in almost all organisms

7. Comparative Biochemistry
Nucleic acids, proteins and enzymes are similar in all organisms
The closer the relationship, the greater the similarity in biochemistry

8. Comparative Anatomy Similarity in physical structures
Homologous Structures- parts that are similar in structure but have a different function
Ex: the forearm of a human, the wing of a bird and the flipper of a whale all have a similar arrangement and number of bones but they have a different function

9. Comparative Embryology
Embryos of vertebrates resemble each other very closely

10. Lizard Tortoise Pig Human

11. Origins of Life
Spontaneous Generation- the belief that living things could be produced from non living things
EX- people believed that water in a pond produced frogs

12. Redi’s Experiment helped to disprove spontaneous generation

13. The Heterotroph Hypothesis
The theory of how primitive life forms developed on primitive earth

14. Heterotroph Hypothesis
Conditions of the primitive earth
The atmosphere contained ammonia, methane, and hydrogen ( no oxygen)

15. The earth was described as being a hot body rich in inorganic substances and energy
The sources of energy included lightening, solar radiation, and radioactive materials

16. The oceans were gases and minerals mixed in a “ hot thin soup”

17. Energy caused the synthesis of organic compounds in the “hot thin soup” from inorganic compounds
Coacervates formed (organic compounds clustered together)
These coacervates absorbed new molecules (heterotrophic nutrition)

18. When the coacervates became too large, they split (reproduction)
When the coacervates became too large, they split (reproduction). These are the first living things?!.
These organisms used anaerobic respiration for energy and released carbon dioxide.
Some organisms developed that could use carbon dioxide and the sun’s energy to synthesize organic compounds. These were the first autotrophs. They released oxygen.

19. Organisms developed that could use oxygen for respiration – aerobic organisms.
Anaerobic Heterotrophs  Anaerobic Autotrophs  Aerobic Organisms

20. Theories of Evolution Lamarck
Use and disuse – new organs arise according to the needs of the organism, unused organs are lost “Use It or Lose It”
Transmission of acquired characteristics- characteristic acquired by an individual are passed on to the offspring
Ex –Man lifts weights and becomes muscular and his offspring will be born muscular?
Ex- Woman learns piano – children will be good pianists?

21. This Theory is Wrong!

22. Weismann – cut the tails off mice to see if offspring would be born without tails
All offspring had tails
Disproved Lamarcks Theory!

23. Darwin’s Theory of Evolution
Darwin was the naturalist on the ship the HMS Beagle( )
He made many observations of fossils and animals that he saw in South America and the Galapagos Islands

24. Upon his return and after much research he come up with several related theories:
1. Evolution did occur
2. Evolutionary change is gradual, occurring over thousands to millions of years
3. The primary mechanism for evolution is a process called natural selection

25. Darwin’s Theory of Evolution
Evolution occurs as a result of natural selection and variation

26. Overproduction
In each generation, more offspring are produced than can survive
This leads to :

27. Competition
Individuals struggle to survive by competing for food, water, shelter, mates etc

28. Variation
Characteristics that are different among organisms of the same species
Ex- size, strength, color, disease resistance

29. Adaptations
An inherited trait that increases an organism’s chance of survival

30. Survival of the Fittest
The organisms that are best adapted to the environment will live long enough to reproduce

31. Reproduction
Surviving individuals pass their traits on to their offspring

32. Speciation
An accumulation of passed on variations will allow a new species to form

33. Darwin’s Theory does not explain a genetic basis for the variations that occur in organisms

34. DeVries stated that mutations were a source of new traits that permits evolution to occur

35. Modern Theory of Evolution
Is a combination of Darwin’s Theory and DeVries

36. Natural Selection
Traits that have a high survival value are retained and passed on
Traits with a low survival value diminish in frequency
Changes in the environment may change the survival value of a trait

37. Examples Peppered Moths Microorganisms resistant to penicillin
Insects resistant to pesticides

38. Peppered Moth Activity

39. Time Frame for Evolution
Gradualism – evolution is slow, gradual and continuous

40. Time Frame for Evolution
Punctuated Equilibrium- species have long periods of stability interrupted by brief periods of change (mutations), during which new species may evolve

42. Common Ancestors
Organisms that exhibit similar structures, biochemistry, etc. have common ancestors
More similarities  Closer the evolutionary relationship
Illustrated by Phylogenetic Tree

43. Phylogenetic Tree

44. Phylogenetic Tree

45. Extinction When all members of a species disappear from the earth.
The mortality (death) rate exceeds the birth rate.
Extinction usually occurs because of changes in the environment
If there is variation within a species, it is more likely that some will survive.