1. Evolution

2.
Is evolution just a theory?
Why is it so controversial?

3. Fossils indicated that living things have changed.
Several scientists had ideas to explain how.

4. History of Evolutionary Thought 1) Lamarck (1744–1829)
Lamarck’s Theory of Inheritance of Acquired Characteristics
Organisms could change themselves in life
Organisms gain traits they need
Pass on these changes to offspring

5. EX: giraffe’s necks grow longer because they stretch to reach the high leaves.
X “Use/disuse” mechanism is wrong

6. Lamarck Think about it... -Can you make yourself any height you want?
-If you lose an arm, will all your kids have one less arm?
-If you are born with a birthmark, will all your kids have it to?

7. 2) Thomas Malthus ( )
Darwin was influenced by Thomas Malthus, a political economist
Central theme of Malthus’ Essay on the Principle of Population (1798): Populations will grow to a size that can be supported by the environment. Overpopulation leads to hunger, disease, & struggle for survival.
Darwin proposed that in the struggle for survival, some competitors would be better equipped to survive.

8. 3) Charles Darwin (1809-1882) So who is Darwin?????? English scientist
Was a naturalist on the HMS Beagle for 5 years (traveled around the world, mostly the southern hemisphere, including the Galápagos Islands) from 1831 to 1836
Published On the Origin of Species in 1859 introducing his theory of “natural selection” based on his observations while aboard the Beagle

9. Voyage of the HMS Beagle

10. Competition Wallace in South America & South East Asia
Both naturalists came up with the idea of evolution through natural selection independently of the other
Both published their findings in 1858
“Logically, some organisms would be able to survive better than others”
Therefore, they would pass on their traits to their offspring

11. Darwin’s Finches Good example of how evolution occurs
Each Galapagos Island has its own unique species of finch
Each finch had a head and body well-adapted for life on that island
The finches were different species, but looked similar

12. Darwin realized that the finches had a common ancestor
He proposed that originally a few seed-eating finches had flown to the islands from the mainland. Over millions of years, the finches adapted to the foods available on each island – and evolved into separate species.

13. In conclusion……
NATURE had selected which finches were best fit for that type of environment.
Finch Game

14. Then Darwin made 2 deductions:
Since most offspring don’t survive, all organisms must have to struggle for survival. (Others are eaten, or die of disease.)
2. The ones who survive and reproduce will pass on their genes.

16. How Does Evolution Work ??

17. Natural Selection
Nature selects (NATURAL SELECTION) those that are best adapted to survive.
“Survival of the Fittest”
Any adaptive advantage (a favorable trait) that an organism has
is passed to offspring.

18. 4 Keys to Natural Selection
1. All organisms produce more offspring than can survive.
2. Some organisms in a species survive and reproduce better than others.
3. Organisms in a species show wide variation.
4. Variations are inherited and passed on to the next generation.

20. Mutations play big a role in natural selection by creating VARIATION.
Example:
The Rabbit Tale -
Maybe once upon a
time all rabbits had short
ears and managed OK.

21. Then one day a mutant with big ears
was born.
She was always the first to dive for cover.
Pretty soon, she had babies; some inherited her big ears.
They all dived for cover as fast as their mom – faster than the short earred rabbits.
Eventually, only the big earred rabbits are left.

23. Example of evolution through natural selection
Cockroaches
Over the centuries, as man and cockroaches have shared homes, cockroaches have become smaller and flatter – easier access to hiding places.
(Large, fat ones more easily stomped.)

24. Another example - antibiotic resistance by natural selection
Someone gets sick
Give them antibiotics
99% of the bacteria are killed; only the antibiotic resistant mutants survive
They thrive and flourish, person gets sick again
Bacteria cannot be killed by antibiotics

25. Artificial Selection Breeding for certain traits Environment is very
easy – all organisms
survive
Breeder for (selects)
the trait he or she
Wants in offspring
Ex – color, size

27. Review

28. Evidence of Evolution Fossils Similarity of embryos
Homologous and analogous structure
Vestigial structures
Similarities in macromolecules

29. A)Fossils – tell us that organisms that once lived on Earth are not here any more.
Fossils found closer to the surface are YOUNGER than the fossils found below
Fossils found in the same layer, indicate that they existed at the same time

30. B) Embryos of all vertebrates are similar – common ancestor

31. C) Homologous Structures – similar structures with similar functions
C) Homologous Structures – similar structures with similar functions. Suggest a common ancestor.

32. C) Analogous Structures
Structures in unrelated organisms that carry out same functions.
Exs: -Lungs in mammals
and gills in fish
-Wings of insects and
wings of birds

34. D) Vestigial Structures
Reduced or nonfunctional structures
Examples: appendix, wisdom teeth, human tail bone
Interpretation: the vestigial structure was functional in some ancestor of the modern organism
Snakes have pelvic bones; they are known to be the descendants of four-legged reptiles.

35. Vestigial features.The skeleton of a baleen whale, a representative of the group of mammals that contains the largest living species, contains pelvic bones. These bones resemble those of other mammals, but are only weakly developed in the whale and have no apparent function.

36. Appendix in human

37. E) Similarities in Macromolecules-
Proteins
MORE differences in amino acid sequences of distantly related species, LESS differences between species that are more closely related.
Nucleic Acids (what is a nucleic acid???)
MORE differences in DNA sequences b/t distant relatives, LESS differences between species that are more closely related.

38. DNA sequences
Animal
Human
Gorilla
Chimpanzee
Orangutan

39. Three pattern types of evolution
1) Coevolution
2) Convergent Evolution
3) Divergent Evolution

40. Coevolution
When two species are in close association and evolve together. Also when a species evolves as a result of evolution in another species.
These organisms may depend exclusively on each other & be highly specialized!

41. Convergent Evolution
When un-related species becomes more similar over time.
An example is a Dolphin (mammal) and fish.

42. Divergent Evolution
When related species become more different over time.
An example is breeding dogs
Divergent evolution is the result of:
1)artificial selection
2) adaptive radiation – where many species evolve from one species

43. Label what type of evolution is occuring

44. Convergent or Divergent??

45. Question: Convergent or Divergent Evolution? Why?
Dolphins and Penguins
Answer: Convergent Evolution
Dolphins are mammals
Penguins are birds
Both have developed flippers to swim, stream like bodies, blubber to keep warm in water

46. Genetic Equilibrium
Genetic Equilibrium is a balance of alleles within a population
****Genetic equilibrium does not exist *****

47. Five Reasons Why Genetic Equilibrium does not exist
Migration
Mutations
Genetic Drift
Non- Random Mating
Natural Selection

48. 1) Migration – the movement into or out of a population
Immigration – the movement INTO a population
Emigration – the movement OUT a population
The genes will move also! 48

49. 2) Mutations – the alteration in alleles, or genetic information
New traits will form, while harmful traits will eventually be eliminated
Creates VARIATION
3) Genetic Drift - Changes in a population that are caused by change or random events.
EX: large volcano, fire, flood, disease
More effect on a small population more than large population. 49

50. 4) Non-random mating – leads to less “selection” and all alleles would have an equal chance of being passed on. 5) Natural Selection – where the fittest will survive. The bad traits will be eliminated from the population due to natural selection. 50

51. Tempo of Evolution
Gradualism is a process of evolution in which the formation of new species occurs gradually
Punctuated Equilibrium is a process in which the formation of new species occurs rapidly between periods of little or no change.
Formation of new species is called Speciation

54. Types of Selections

55. Natural Selection can alter gene (trait) frequencies of a population in three ways:
Stabilizing Selection
Directional Selection
Disruptive Selection

56. 1) Stabilizing Selection
Most common form
Nature favors the average trait
Selection against the two extremes
Ex. Babies born with low and high birthweights have a lower chance for survivial than average
Low
Average
High

57. 2) Directional Selection
Nature favors one extreme
Ex. Peppered moth
-Dark Moth survived on dark sooty background.
-When pollution became lighter, nature favored light colored moth.
Light
Medium
Dark

58. 3) Disruptive Selection
Nature favors both extremes
Splits population into 2 groups
Ex. Galapagos Finches
Small Birds, Small Seeds
Large Birds, Large Seeds.
Average Bird must compete with both
Small
Average
Large