1. Charles Darwin and the theory of natural selection
Biology I

2. I. Before Darwin Jean Baptiste Lamarck: acquired characteristics
Evolve from simple to complex
Organisms want to adapt

3. I. Before Darwin
Later disproved

4. II. Darwin At 21, took a job as a naturalist on the HMS Beagle
Collected specimens, took notes of different organisms

5. His voyage:

6. II. Darwin Sailed to Galapagos Islands
All new species, but similar to those found elsewhere

7. Finches most famous
Had slightly different beaks from island to island
Differed by each bird’s diet

8. II. Darwin Darwin 22 years developing theory of natural selection
Pressured into publishing by Alfred Wallace (competition)
Published On the Origin of Species by Natural Selection

9. Misconception 1:“Evolution is a theory about the origin of life.”

10. Either an organism has genes that enable its survival or it doesn’t.
Misconception 2: “Natural selection involves organisms ‘trying’ to adapt.” (Lamarck)
Either an organism has genes that enable its survival or it doesn’t.

11. Misconception 3 : “Natural selection gives organisms what they ‘need
A population either has the ‘right’ variation or it doesn’t. If it doesn’t, the population may die out.

12. Misconception 4: “Evolution is like a climb up a ladder of progress; organisms are always getting better.”

13. III. Natural Selection 4 Requirements for Natural Selection
1. Variation
2. Differential Reproduction(Selective Pressures)
3. Heredity
4.Lots of Time

14. III. Natural Selection Four steps
1. Organisms produce more offspring than can survive
competition
Only the best are going to survive

15. III. Natural Selection 2. Individuals have variations.
Color, size, speed, etc.
The variations that natural selection acts on are genetically linked

16. III. Natural Selection
3. Beneficial variations survive, pass traits to offspring
Passed through DNA
(Yay Genetics!!)

17. III. Natural Selection
4. Over time variations become more frequent in population
Results in population being different than ancestors

18. III. Natural Selection Natural selection usually takes a long time
Selection for a particular variation depends on environment

19. Example of Natural Selection

20. Evolution
Evolution is the change in a population over time
Not this!

21. IV Evidence for Evolution
Adaptations/Biogeography
Comparative Anatomy
Fossil Record
Comparative Embryology
Biochemistry

22. Types of Adaptations An Adaptive Trait- variation that is helpful
Thick fur in cold places
Maladaptive Trait- variation that is harmful
Poor eyesight

23. Structural Adaptations
Physical traits

24. Mimicry-An adaptation
Enables one species to resemble another species.
Ex.-harmless species looks like a harmful one, good tasting vs. bad tasting.

26. 

27. Camouflage-An adaptation
A species blends in with its environment to avoid predators.
Ex.- peppered moth,
leaf frog

28. Anatomy- Homologous Structures
Common evolutionary origin. Similar in arrangement or function or both.
Example: forelimbs of a whale, a cat, and a bird wing.

29. Anatomy- Analogous Structures
No common evolutionary origin, but similar in function.
Wings of a bat and wings of a moth.

30. Anatomy- Vestigial Structures
No function now but was probably useful to an ancestor.
Ex. A whale has leg bones, a snake has leg bones, we have a tail bone and wisdom teeth.

32. Fossils Determine relationships among organisms.
Ancestors of whales were probably land-dwelling, doglike animals.

34. Embryology Earliest stage of growth and development
Embryos of a fish, a chicken, a pig, a cow, a rabbit, and a human are almost identical.
They all have gill slits and a tail.

36. Biochemistry Comparisons of DNA and RNA
More DNA bases in common the more closely related

37. V. Mechanisms of Evolution
Genetic Drift
Gene Flow
Artificial Selection
Natural Selection
Sexual Selection

38. Genetic Drift
Change in allele frequency by CHANCE

39. Gene Flow
Change in allele frequency as a result of MIGRATION

40. Humans choose desired traits and manipulate breeding
Artificial Selection
Humans choose desired traits and manipulate breeding

41. Sexual Selection
Special case of Natural Selection
Variations selected for their ability to attract a mate

42. Geographic isolation Physical barrier divides a population
New selective pressures
Two different species

43. Reproductive isolation
No longer able to mate
Different genetic information
Mating behavior differences

44. Selective Pressures
Environmental
Examples: drought, lack of food, extreme temperatures, predation

45. Sources of Variation GENE FLOW moves genes among populations
SEXUAL REPRODUCTION introduces new gene combinations
Random MUTATIONS in DNA lead to the formation of new alleles (sound familiar?)

46. Mutations
Can be beneficial, neutral, or harmful for the organism
Only mutations in gametes are inherited by offspring

47. VI. Natural selection affecting populations
Three major types of natural selection are:
Stabilizing Selection
Directional Selection
Disruptive Selection

48. Stabilizing selection
Average individual is selected for

49. Directional selection
One extreme trait is selected for

50. Disruptive Selection
Both extremes are selected for
Average selected against.

51. How do we determine a new species?
A species is considered a group of organisms that can:
Interbreed
Produce Fertile offspring
Two species of meadowlark