1. Evolution and Darwin

2. Evolution is surrounded by controversy
Why?
People have religious beliefs
People don’t like the idea that “Human’s came from monkeys”
There is a lot more to evolutionary theory than monkeys.

3. The Camps surrounding Evolutionary Theory
Creationists- believe a supreme being (God, Allah, Great Spirit etc.) created everything as it is today
Intelligent Design-followers believe the living world is too complex for it to just happen. Some intelligent form had to be behind making the blue prints.
Evolutionists- believe organisms changed over time to their present forms.

4. What do you need to do to be successful with Unit #4?
You do not have to believe Evolutionary Theory.
You only have to understand its principals and concepts that we learn in our future lessons

5. Old Theories of Evolution
Jean Baptiste Lamarck (early 1800’s) proposed:
“The inheritance of acquired characteristics”
He proposed that by using or not using its body parts, an individual tends to develop certain characteristics, which it passes on to its offspring.

6. “The Inheritance of Acquired Characteristics”
Example:
A giraffe acquired its long neck
because its ancestor stretched
higher and higher into the trees
to reach leaves, and that the
animal’s increasingly lengthened
neck was passed on to its offspring.

7. Would these acquired characteristics get passed on to their offspring?
Of course not. The acquired characteristics did not cause changes in the sex cells

8. Larmarck’s Theory Use and Disuse
-Fish in caves don’t use their eyes so they disappear
-Elephants use their trunks a lot so they get longer
Although false, his theory was the first attempt to explain how organisms adapted to their environment over time

9. Charles Darwin
Influenced by Charles Lyell who published “Principles of Geology”.
This publication led Darwin to realize that natural forces gradually change the Earth’s surface and that the forces of the past are still operating in modern times.

10. Charles Darwin
Darwin set sail on the H.M.S. Beagle ( ) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals.
On the Galapagos Islands,
Darwin observed species
that lived nowhere else in
the world.
These observations led
Darwin to write a book.

11. HMS Beagle and its route

12. California Academy of Sciences in San Francisco
Mr. Down’s spent the day there on a summer trip to visit my son and daughter
The CAS had an incredible Darwin Exhibit

14. You will use this chart for Beaks of Finches Lab

15. Darwin’s Finches

16. Charles Darwin
Wrote in 1859: “On the Origin of Species by Means of Natural Selection”
Two main points:
1. Species were not created in their present form, but evolved from ancestral species.
2. Proposed a mechanism for evolution: NATURAL SELECTION

17. Natural Selection
Individuals with favorable traits are more likely to leave more offspring better suited for their environment.
Also known as “Differential Reproduction”
Example:
English peppered moth (Biston betularia)
- light and
dark phases

18. Artificial Selection
The selective breeding of domesticated plants and animals by man.
Selective Breeding is also called
Artificial selection
Question:
What’s the ancestor of the domesticated dog?
(Canis familiaris)
Answer: WOLF (Canis lupus)

19. Mr. Downs’ dog Clancy at 6 weeks old

20. Both of these trees are in my yard and are the same species (Thuja occidentalis)
Which one looks better? Why?
They are both in the same environment (water, sun, nutrients are the same). Why do they look so different?
Different Traits in their DNA
Which one do you think humans selected desirable traits in deliberate plant crosses? A B

21. Darwin is the founder of Modern Evolutionary Theory
Science attempts to:
-Describe events based on phenomena we
can observe
-Explain events of the past in terms of
events we can observe today
-Make predictions about future events

22. A Theory such as Evolution Theory is
supported by a lot of data collected by
thousands of Scientists
Theories can be discarded (i.e.Lamarck) or revised as scientist get new information
Theories can’t be proven with absolute certainty (i.e.-Gravitational Theory, Cell Theory, Contagious Disease, Genetics)

23. Darwin is the founder of Modern Evolutionary Theory
Evolution is the processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today.
Evolution results in
A change in the
genes!!!!!!!!

24. Darwin never did claim that humans originated from monkeys.
Darwin claimed that humans and monkeys (well, apes really) have a COMMON ancestor. That is, they originated from the same species many years ago

25. Evolution is the process (mutation, adaptation, natural selection and extinction) of change in a population through generations
Existing life forms have evolved from earlier life forms.
Evolutionary theory is a unifying principle for the biological sciences. ( Genetics, Biochemistry, Anatomy, Physiology etc.)

26. Evolution Theory provides
an explanation for the
differences/ similarities in
structure, function, and
behavior among life forms.

27. Evidence of Evolution Cladograms or phylogenetic trees are
graphic representations
of species relationships.
Common Ancestor

28. Evidence of Evolution
1. Geographical distribution of species. Alfred Russell Wallace was also known as the "father of biogeography.
Biogeography -the study of the past and present geographical distribution of organisms.
Reproductive Isolation-
prevents mating with birds
on the other islands. Two
populations develop
independently

29. 2. Fossil Record:
Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence).
Younger Fossils
Older Fossils

30. Evolution of the horse
What changes do you notice in moving from the bottom to the top?
Increase in size
Changes in the leg bones

31. Relative Dating-In relative dating, something is determined to be older or younger than something else by using the laws of superposition.
-Layers (strata) close to the surface are younger
-Deeper Layers contain the oldest strata
Absolute Dating-dating determines the actual age of artifacts
-One of the most widely used
and well-known absolute dating
techniques is carbon-14
dating, which is used to date
organic remains.

32. Evidence of Evolution
3. Taxonomy-classification of organisms into different categories based on their physical characteristics and presumed natural relationships (remember Did King Philip Come Over………..?)
In 1735, Carolus Linnaeus
published a book in which he
outlined his scheme for classifying
organisms and is still in use today
The Linnaean system uses two Latin name categories, genus and species , to designate each type of organism.

33. 4. Homologous structures:
Structures that are similar because of common ancestry (comparative anatomy)

34. Homologous Structures- structures shared by related species because they have been inherited from a common ancestor.
(flipper of a whale and hand of a human)
Analogous Structures- Analogous structures serve the same function in different species but is not a result of sharing a common ancestor. (wing of a butterfly and wing of a bird)
Vestigial Structures- organ or structure that once was useful in an animal’s evolutionary past, but that now is useless or very close to useless. (wing of an ostrich)

35. My favorite Vestigial Structures
Whale
Snake

36. Plica Semilunaris -it is the “crusty” factory
Plica Semilunaris -it is the “crusty” factory. It secretes a sticky mass that collects any foreign materials. All this trash is surrounded by the sticky gook so that it does not scratch the sensitive cornea.

37. Darwin’s point is found in the majority of mammals, and humans are no exception. It is most likely used to help focus sounds in animals, but it no longer has a function in humans.
Wisdom Teeth - Early humans ate a lot of plants – and they needed to eat them quickly enough and eat a sufficient amount in one day to get all of the nutrients they needed.

38. Evidence of Evolution 5. Comparative embryology:
Study of structures that
appear during embryonic
development.
Any ideas on why the
embryos are so similar?
Scientist believe that
mutations at early stages
result in death or
spontaneous abortion.

39. 6. Molecular biology: DNA and proteins (amino acids)
Diagram shows chromosome
1 next to the human chromosome 1.
The A-T bases are black and
the G-C bases white.
Blue areas in the rendered chromosomes identify
bases not known yet.
DNA Analysis can show us
how closely related different
organisms are.

40. -There is no thought involved in Natural selection -There are no choices in Natural Selection -It is all about the genes an organism is born with

41. Concepts of Natural Selection
1. Overproduction -- Within a population,
more offspring are born than can possibly survive.
These are tadpoles that hatched from one female toad. Do you think many will survive?

42. 2. Competition – Over production results in struggle for space, water, food, light, mates or other limited resources
3. Variations-Members of populations show variations (differences in traits) that make certain individuals better adapted to survive

43. 4. Natural Selection-Some variations are more
helpful than others, there is a natural selection against organisms that can’t adapt.
5. Organisms that can’t adapt DIE and
some populations may become extinct

44. 6. Survival of the Fittest -- The individuals who
survive are the ones best adapted.
7. Inheritance of variations-Organisms with helpful
variations survive and live long enough to
REPRODUCE.
8. The best adapted individuals survive and
reproduce, passing on the favorable variations to their offspring (& population ). These changes improve the fitness of a species (population) in its environment

45. 9. If an organism does not live long enough
9. If an organism does not live long enough to reproduce it has NO EFFECT ON THE EVOLUTION OF THE POPULATION.
10. Individuals can’t evolve, only populations can evolve. (make sense because genes have to be passed on to offspring for evolution to take place.
11. Evolution of New Species-Over long periods of time, so many variations may accumulate that a population may become a new species. This process is called Speciation

46. Some Sources of Variation in Modern Natural Selection Theory
1. The genetic basis for variation within a species is provided by mutations and
sexual reproduction. (crossing over
and recombination)
2. Mutations are spontaneous
and provide the raw material for
evolution.

47. Modern Natural Selection Theory
1.) All species have the potential to increase in numbers.
2.) There is a finite amount of resources for any species. Species tend to make too many
organisms for these resources.
3.) Species will show genetic variability due to mutation, crossing over, and genetic recombination (during fertilization) of genes.
4.) The scarce finite resources of the environment will select those offspring better able to survive and less fit offspring may die.

48. 5.) Variations within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions.
-Traits which are beneficial to the survival of an organism in a particular environment tend to be retained and passed on, and therefore, increase in frequency within a population.
-Traits which have a low survival value to organisms tend to diminish in frequency from generation to generation.
-If environmental conditions change, traits that were formerly associated with a low survival value may, in a changed environment, have greater survival value and increase accordingly.

49. Population Genetics The science of genetic change in population.
Hardy-Weinberg equation is important and will be discussed shortly.

50. Vocabulary
Population- A localized group of individuals belonging to the same species.
Species- A group of populations whose individuals have the potential to interbreed and produce viable offspring.
Gene Pool-The total collection of genes in a population at any one time.

51. Hardy-Weinberg Principle
The concept that the shuffling of genes that occur during sexual reproduction, by itself, cannot change the overall genetic makeup of a population.

52. Hardy-Weinberg Principle
This principle will be maintained in nature only if all five of the following conditions are met:
1. Very large population
2. Isolation from other populations
3. No net mutations
4. Random mating
5. No natural selection

53. Hardy-Weinberg Principle
Remember:
If these conditions are met, the population is at equilibrium.
This means “No Change” or “No evolution”.
The Hardy–Weinberg equilibrium is impossible in nature. Genetic equilibrium is an ideal state that provides a baseline to measure genetic change against.

54. Macroevolution
The origin of taxonomic groups higher than the species level.
Involves very long periods of time
Grand scale changes in organism
Scientists can see changes in fossils of Intermediate species
Sea cow (manatee)
ancestor with legs

55. Microevolution
A change in a population’s gene pool over a secession of generations.
Evolutionary changes in species over relatively brief periods of geological time.

56. Five Mechanisms of Microevolution
1. Genetic drift:
Change in the gene pool of a small population due to chance.
Two examples:
a. Bottleneck effect
b. Founder effect

57. a. Bottleneck Effect
Genetic drift (reduction of alleles in a population) resulting from a disaster that drastically reduces population size. (result are similar to inbreeding)
Examples of disasters:
1. Earthquakes
2. Volcano’s
3. Droughts

58. b. Founder Effect
Genetic drift resulting from the colonization of a new location by a small number of individuals.
Founder populations are
often found on islands
Results in random change
of the gene pool.
Mutiny on the Bounty (1789): Population of 9 mutineers, 8-9 Tahitian females and 6 Tahitian males to uninhabited Pitcairn Island.

59. Five Mechanisms of Microevolution
2. Gene Flow:
The gain or loss of alleles from a population by the movement of individuals or gametes.
Immigration- movement out/away
Emigration- movement in

60. Five Mechanisms of Microevolution
3. Mutation:
Change in an organism’s DNA that creates a new allele.
4. Non-random mating:
The selection of mates
other than by chance.
5. Natural selection: Differential reproduction- competition for mates, those best adapted survive and produce more offspring.

61. Modes of Action Natural selection has three modes of action:
1. Stabilizing selection
2. Directional selection
3. Diversifying selection
Number of
Individuals
Size of individuals
Small Large

62. 1. Stabilizing Selection
Acts upon extremes and favors the intermediate.
Number of
Individuals
Size of individuals
Small Large

63. 2. Directional Selection
Favors variants of one extreme.
Number of
Individuals
Size of individuals
Small Large

64. 3. Diversifying Selection
Favors variants of opposite extremes.
Number of
Individuals
Size of individuals
Small Large

65. Speciation
The evolution of new species.

66. Reproductive Barriers
Any mechanism that impedes two species from producing fertile and/or viable hybrid offspring.
Different species most likely have different number of chromosomes
Two barriers:
1. Pre-zygotic barriers
2. Post-zygotic barriers

67. 1. Pre-zygotic Barriers a. Temporal isolation:
Breeding occurs at different times for different species.
b. Habitat isolation:
Species breed in different habitats.
c. Behavioral isolation:
Little or no sexual attraction between species.

68. 1. Pre-zygotic Barriers d. Mechanical isolation:
Structural differences prevent gamete exchange.
e. Gametic isolation:
Gametes die before uniting with gametes of other species, or gametes fail to unite.

69. 2. Post-zygotic Barriers
a. Hybrid inviability:
Hybrid zygotes fail to develop or fail to reach sexual maturity.
b. Hybrid sterility:
Hybrid fails to produce functional gametes.
c. Hybrid breakdown:
Offspring of hybrids are weak or infertile.

70. Interesting but not Fertile
Lion
Tiger- 38
Horse
Donkey- 62
Mule
Human - 46
Chimpanzees- 48
Gorilla- 48

71. Allopatric Speciation
Induced when the ancestral population becomes separated by a geographical barrier.
Example:
Grand Canyon and ground squirrels

72. Adaptive Radiation
Emergence of numerous species from a common ancestor introduced to new and diverse environments.
Example:
Darwin’s Finches

73. Sympatric Speciation
Result of a radical change in the genome that produces a reproductively isolated sub-population within the parent population (rare).
Example: Plant evolution - polyploid
A species doubles it’s chromosome # to become tetraploid.
reproductive sub-population
Parent population

74. Interpretations of Speciation
Two theories:
1. Gradualist Model (Neo-Darwinian):
Slow changes in species overtime.
2. Punctuated Equilibrium:
Evolution occurs in spurts of relatively rapid change.

75. Convergent Evolution
Species from different evolutionary branches may come to resemble one another if they live in very similar environments.
Example:
1. Ostrich (Africa) and Emu (Australia).
2. Sidewinder (Mojave Desert) and
Horned Viper (Middle East Desert)

76. Coevolution
Evolutionary change, in which one species act as a selective force on a second species, inducing adaptations that in turn act as selective force on the first species.
Example:
1. Acacia ants and acacia trees
2. Humming birds and plants with flowers with long tubes

77. Speciation-creation of new species
Morphology-study of structure
Geographic Isolation (Reproductive Isolation)-
Divergent Evolution-
Convergent Evolution
Coevolution-
Adaptive Radiation-
Genetic Drift-

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