2. Charles Darwin (1809-1882) Sailed around the world 1831-1836

3. What did Darwin’s Travels reveal
The diversity of living species was far greater than anyone had previously known!!
These observations led him to develop the theory of evolution!!

4. How did tortoises and birds differ among the islands of the Galapagos?
Each island had its own type of tortoises and birds that were clearly different from other islands

5. Galapagos Turtles

6. Evolution is when organisms change over time
Evolution is when organisms change over time. So, modern organisms descended from ancient ones

7. Evolution is a Theory – Just like Gravity!
Evolution is a well supported explanation of phenomena that have occurred in the natural world
A theory in science is a well tested hypothesis, not just a guess

8. Previous Theory by Lamark Theory of acquired characteristics
Lamark said organisms acquired traits by using their bodies in new ways
These new characteristics were passed to offspring
Lamark was totally wrong!

10. Darwin finally published his ideas in 1859
Other naturalists were developing the same theory that Darwin did.
Even though he was afraid of the Church’s reaction to his book he wanted to get credit for his work.

11. Artificial Selection
nature provides variation, humans select variations that are useful.
Example - a farmer breeds only his best livestock

12. Natural Selection
The traits that help an organism survive in a particular environment are “selected” in natural selection

16. Natural Selection and Species Fitness
Overtime, natural selection results in changes in the inherited characteristics of a population.
These changes increase a species fitness (survival rate)

17. Survival of the Fittest
populations with the most desirable traits and ability to compete will live long enough to reproduce and pass on those beneficial traits.

18. 6 key points
Overproduction: living things produce more offspring than needed for the species to survive
Ex. Populations remain constant because only a small fraction live long enough to reproduce (food is a limiting factor)

19. 6 key points
Competition: struggle between organisms for food, shelter, mates and living space
Ex. Resources for life are limited so an organisms must compete within its species and with other species to survive long enough to reproduce

20. 6 key points
Variation: differences (structural, molecular, and behavioral) within a species that makes individuals different
Ex. Individuals vary in their abilities to get food, escape enemies, or find and attract a mate

21. 6 key points
Adaptation: inherited traits that improve an organisms chances of survival and reproduction in a certain environment “ Survival of the Fittest!”
Ex. Individuals that are better adapted to the environment will live long enough to reproduce
Camofluage or blending coloring

22. 6 key points
Reproduction: Individuals that have favorable traits and better adapted to survive will pass on these traits to future offspring
Ex. Good genes survive and bad ones are eliminated

23. 6 key points
Speciation: A new species is formed over many generations of favorable adaptations gradually accumulate and non-favorable ones disappear.
Ex. So many gradual changes accumulate that a new species emerges

24. Camouflage
Blends into the environment

25. Warning Coloration
Shows a predator (or prey) that they are unpleasant to eat.

26. Mimicry
Resembles another species to gain an advantage at survival

27. Speciation Favorable adaptations accumulate Unfavorable disappear
All changes may eventually result in a new species

28. Mutations Source of genetic variations May be harmful or helpful
The mutation could turn a harmful allele into a helpful trait

29. Summary of Darwin’s Theory
1. Organisms differ; variation is inherited
2. Organisms produce more offspring than survive
3. Organisms compete for resources
4. Organisms with advantages survive to pass those advantages to their children
5. Species alive today are descended with modifications from common ancestors

30. Evidence of Evolution 1. Fossil Record Law of Superposition
Theory of plate tectonics
2. Geographic Distribution of Living Species
3. Comparative Anatomy
Homologous structures
Analogous structures
Vestigial structures
4. Similarities in Embryology

31. Evidence of Evolution
Fossil Record provides evidence that living things have evolved
Fossils show the history of life on earth and how different groups of organisms have changed over time

32. Relative vs. Absolute Dating

33. Relative Dating Can determine a fossil’s relative age
Performed by estimating fossil age compared with that of other fossils – law of superposition
Drawbacks – provides no info about age in years

34. Absolute dating Can determine the absolute age in numbers
Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain
Drawbacks - part of the fossil is destroyed during the test

35. Primate Fossils
Australopithecus Homo erectus Homo sapien

36. Primate Brain Capacity

37. Primate Bone structure

38. Homo habilis = handy human 1.5 to 2 mya
Homo erectus 1.6 mya
Homo habilis = handy human 1.5 to 2 mya
bipedal

39. Cro-Magnon 35,000 to 40,000 ya Neanderthals 35,000 to 100,000 ya

40. (fully modern fossils 100,000 ya)
Modern Homo sapien
(fully modern fossils 100,000 ya)

41. Theory of Plate tectonics
A theory that states that the earth’s crust is made up of a number of plates which move over a liquid crust that get created and destroyed over time.

42. Pangea
Two hundred million years ago (Ma), research suggests that all the continents were one large mass which was named Pangea.
Terrestrial organisms were able to migrate across all the continents and were only limited by their biotic potential.

44. Biodiversity
As Pangea began to separate into separate continents 130 Ma, creating physical barriers such as seas, restricting migration to within the continents.
Gene pools of species are separated and as they are exposed to different physical (i.e. climate) and biotic (i.e. change in predators) conditions, each portion of the species adapts differently and eventually forms new species on the separated continents.
This process is known as speciation.

45. Biodiversity
Changes in physical and biotic conditions will also lead to the creation of new species increasing the diversity of habitats and niches.
This also provides the space for new species to evolve into these habitats.
The end result of the separation of Pangea into today’s continental configuration is that plate tectonics has been one of the main driving forces promoting biodiversity of organisms.

46. Evidence of Evolution Geographic Distribution of Living Species
Similar animals in different locations were the product of different lines of descent

48. Evidence for Evolution – Comparative Anatomy
Turtle
Homologous Body Structures
Structures that have different mature forms but develop from the same embryonic tissues
e.g. Wing of bat, human arm, leg of turtle
Alligator
Bird

49. Homologous Body Structures

50. Evidence for Evolution – Comparative Anatomy
B. Analogous structures: Similar functions, but different internal structures
Similarities:
birds and insects wings both are used for flying
Differences: internal structures and
embryo development are very
different
Picture from:

51. Evidence for Evolution – Comparative Anatomy
C. Vestigial structures – remnants of structures that were once functional in an ancestor (now-reduced in size
and serve little
or no function

52. Vestigial structures in Pythons
Have hind leg bones and non-functional legs

53. Examples: Tail bone: (coccyx) remnant of a reptilian tail Wisdom teeth
Muscles that move nose and ears
Whales and snakes have hind leg bones imbedded in their bodies from four legged ancestors
Molecular similarities-genetic DNA code and proteins

54. Evidence of Evolution Similarities in Embryology
In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.

55. Embryological development

56. Common Ancestors
A common ancestor is a previous species that new species evolve from.
Evolutionary theory suggests that monkeys and humans have a common ancestor.
Misconception: Humans evolved from monkeys. THIS IS NOT TRUE!
WHAT IS TRUE? Humans and monkeys (and apes) have a common ancestor.

58. Common Ancestor:
6 million years ago
Evolutionary Tree

59. Why do scientists use a Tree vs. something else?
Where the branches meet the trunk shows a common ancestor!

60. What are some examples of organisms with a common ancestor?
Monkeys and humans
Land plants and seaweed

61. Evolution is NOT: Evolution is NOT changes in population size
Evolution is NOT individual organisms growing and going through metamorphosis such as a tadpole changing into a frog
Evolution is NOT individual organisms evolving during their life time. THIS IS NOT POSSIBLE!
An organism cannot acquire (get) a better trait during its life and then pass it on to its offspring.

62. How Does Evolution Happen?
Mutations randomly occur to produce variations. Sexual reproduction also creates variations.
Organisms with beneficial variations (adaptations) are better able to survive.
Over time, a variety of beneficial mutations accumulates in the species.
The accumulation of many changes over time can lead to the production of a new species!