1. DESCENT WITH MODIFICATION A Darwinian View of Life AP BIOLOGY Chapter 22
Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006

2. WHO INFLUENCED DARWIN’S THINKING
Figure 22.2
Linnaeus (classification)
Hutton (gradual geologic change)
Lamarck (species can change)
Malthus (population limits)
Cuvier (fossils, extinction)
Lyell (modern geology)
Darwin (evolution, nutural selection)
Mendel (inheritance)
Wallace (evolution, natural selection)
1750
American Revolution
French Revolution
U.S. Civil War
1800
1850
1900
1795
Hutton proposes his theory of gradualism.
1798
Malthus publishes “Essay on the Principle of Population.”
1809
Lamarck publishes his theory of evolution.
1830
Lyell publishes Principles of Geology.
1831–1836
Darwin travels around the world on HMS Beagle.
Darwin begins his notebooks on the origin of species.
1837
Darwin writes his essay on the origin of species.
1844
Wallace sends his theory to Darwin.
1858
The Origin of Species is published.
1859
Mendel publishes inheritance papers.
1865
Image from: AP BIOLOGY by Campbell and Reece

3. Species are fixed (unchanging) BUT recognized similarities
Image from:
Aristotle- ( B.C.)
Species are fixed (unchanging)
BUT recognized similarities
Arranged life forms on a scale of increasing complexity
scala natura- “scale of nature”

4. Binomial Nomenclature: Naming system that gives organisms a
Image from:
Founder of TAXONOMY-1735
Science of grouping & naming
Sought to discover order in the diversity of life “for the greater glory of God”
Each creature was special- NO evolutionary link
Devised classification system based on morphology (form and structure)
( )
Binomial Nomenclature: Naming system that gives organisms a
two part scientific name- Genus species
Still used today

5. LINNAEUS’S SYSTEM Nested hierarchy
Taxon = classification unit to which organisms are assigned
Ex:
Panthera is a taxon at the genus level
Mammalia is a taxon at the class level

6. Kidspiration by Riedell Image Sources: see end of show

7. Kingdom Phylum Class Order Family Genus Species Animalia Chordata
Kids Prefer Cheese Over Fried Green Spinach
Kings Play Chess On Fat Green Stools
King Phillip Cried Oh For Goodness Sake!
Kingdom
Phylum
Class
Order
Family
Genus Species
Animalia
Chordata
Mammalia
Carnivora
Felidae
Panthera
leo

8. GENUS = group of closely related species
(Includes many kinds of bears)
SPECIES = unique to each kind of bear
GENUS = Ursus
Ursus arctos
Ursus maritimus
Ursus americanis

9. Genus and species assignments provide 2 part scientific name
Homo sapiens
Homo sapiens
Image from:

10. Modern Taxonomy has added more Kingdoms AND more levels (DOMAINS)
Linneaus only used 2 kingdoms (Plants & Animals)
Domains are larger than Kingdoms and are based on the differences in ribosomal RNA

11. Ideas that shaped Darwin’s thinking: George Cuvier –
Father of Paleontology
ANTI-EVOLUTONIST
Fossils are remains of
extinct life forms
“CATASTROPHISM” -
boundaries represent floods, droughts, etc. that destroyed many species living at that time

12. Ideas that shaped Darwin’s thinking: 1795 –James Hutton “GRADUALISM”
Profound changes can result
from cumulative effect of
slow but continuous
processes
Proposed that the Earth was shaped by
geological forces occurring over very long
periods of time, and is MILLIONS not
THOUSANDS of years old.

13. Ideas that shaped Darwin’s thinking: 1833-Charles Lyell
Incorporated Hutton’s ideas into
“UNIFORMITARIANISM”
Geological processes that
shaped Earth are still
operating at same rate.
Darwin read his book on the Beagle voyage

14. MODERN GEOLOGY

15. Ideas that shaped Darwin’s thinking: Thomas Malthus (1798)
Ideas that shaped Darwin’s thinking:
Thomas Malthus (1798)
wrote essay on population growth
Human suffering (disease, famine, homelessness, and war) are consequences to human population increasing faster than food and other resources

16. Ideas that shaped Darwin’s thinking: Jean Baptiste Lamarck (1744-1829)
Ideas that shaped Darwin’s thinking:
Jean Baptiste Lamarck ( )
One of first scientists to recognize
that living things changed over time
and that all species were descended
from other species.
1809- Published his ideas about “Inheritance of Acquired Characteristics” the year Darwin was born

17. INHERITANCE OF ACQUIRED CHARACTERISTICS
The male fiddler crab uses its
front claw to attract mates and
ward off predators.
“USE or DISUSE” = Use it or lose it
Through repeated use, the front
claw becomes larger.
The fiddler passes on this acquired characteristic to its offspring

18. What’s wrong with Lamarck’s hypothesis?
Lamarck didn’t know about
genes and how traits are inherited.
Acquired traits are not passed on to offspring
Or are they? New field of EPIGENETICS is exploring this

19. What’s right with Lamarck’s hypothesis?
Lamarck was first to
develop a scientific
hypothesis about
evolution and recognize
that organisms are
adapted to their
environment

20. Slide by Kim Foglia@ http://www.explorebiology.com/

21. Who Was Charles Darwin?
In 1831, 22-year old Charles Darwin left England as naturalist aboard the HMS Beagle for 5 year voyage around the world.
Mission: Chart the South American coastline
Darwin noticed plants
and animals were different
from those he knew in Europe
Wrote thousands of pages
of observations and
collected vast number of
specimens

22. Who Was Charles Darwin?
Darwin spent a month observing life on the Galapagos Islands
Each island has different rainfall
and vegetation and its own unique
assortment of plant and animal
species.
Biology by Miller and Levine; Prentice Hall Publishing©2006

23. Who Was Charles Darwin? Although animals on Galapagos
resemble species on the
South American mainland,
many species were found no
where else in the world = ENDEMIC

24. DARWIN’S
FINCHES
Darwin collected 14 species of finches and hypothesized that the Galapagos had be colonized by organisms from the mainland that had then diversified on the various

25. Who Was Charles Darwin?
After Darwin returned to England in 1836, he spent years examining specimens he brought back from voyage and filling notebooks with his ideas.
He did not rush to publish his ideas because they
disagreed with the fundamental scientific views of his
day.
In 1844 he wrote an essay describing his ideas and
asked his wife to publish it if he died.

26. In 1858 Alfred Russel Wallace, another
Naturalist working in the West Indies,
wrote an essay describing his work that
summarized the same ideas Darwin had
been thinking about for 25 years!

27. Suddenly Darwin had incentive to publish the results of his work!
On the Origin of Species by Means of Natural Selection
presented evidence
and proposed a
mechanism for evolution
that he called
NATURAL SELECTION

28. Darwin’s Theory of Evolution Darwin Presents his Case
Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006

29. Isn’t evolution “just a theory”?
In every day usage “theory” often refers to a hunch or a speculation. When people say, “I have a theory about what happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence.
The formal scientific definition of “theory” is quite different from the every day meaning.
It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.

30. Isn’t evolution just a theory?
In Science a theory is a well supported, testable explanation of phenomena that have occurred in the natural world.
Example:
Cell theory
Atomic theory
Gravitational theory

31. VOCAB
ADAPTATION- Any inherited characteristic that increases an organism’s chance of survival

32. WHAT IS DARWIN’S THEORY?
OVERPRODUCTION of OFFSPRING
Capacity to over-reproduce seems characteristic of all species.

33. WHAT IS DARWIN’S THEORY?
STRUGGLE FOR EXISTANCE means
that members of each species must
compete for food, space, and
other resources.

34. WHAT IS DARWIN’S THEORY?
GENETIC VARIATION is found naturally in all populations
Image from

35. WHAT IS DARWIN’S THEORY?
Some organisms in a population are less likely to survive.

36. VOCAB
Ability of an individual to survive and reproduce in its specific environment = FITNESS

37. WHAT IS DARWIN’S THEORY?
SURVIVAL OF THE FITTEST =
Organisms which are better adapted
to their environment tend to produce
more offspring than organisms without
those traits.

38. results in changes in the inherited characteristics of a population.
WHAT IS DARWIN’S THEORY?
Over time,
NATURAL SELECTION
results in changes in the
inherited characteristics of a population.
These changes increase a
species’ fitness in its environment.
How Does Evolution Really Work?

39. IMPORTANT TO REMEMBER ! POPULATIONS evolve NOT INDIVIDUALS.
NATURAL SELECTION only works on heritable traits.
A trait that is favorable in one environment may be useless or detrimental in another.

40. DESCENT WITH MODIFICATION
WHAT IS DARWIN’S THEORY?
DESCENT WITH MODIFICATION
suggests that each species has
descended with changes
from other species over time.
This idea suggests that all living
species are related to each other
and that all species, living and extinct,
share a common ancestor.

41. What do oranges, broccoli and Butterball turkeys have to do
What do oranges, broccoli and
Butterball turkeys have to do
with EVOLUTION?
(Answers to come in this slide show!)
THINK ABOUT IT

42. EVIDENCE OF EVOLUTION:
________________
3. _______________
4. _______________
5. _______________
6. _________________
7. _______________
Artificial selection
Fossil record
Geographic Distribution
Anatomical homologies
Embryology
Molecular homologies
Can see Natural selection happen

43. ARTIFICIAL SELECTION WORKS Nature provides the variation through
mutation and sexual reproduction and
humans select those traits that they find
useful
EX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.

44. WE’VE DONE IT WITH PLANTS
BIOLOGY by Campbell and Reece Prentice Hall Publishing©2005

45. WE’VE DONE IT WITH ANIMALS
If humans can
select for
beneficial traits,
why can’t nature?
If artificial selection
can achieve so much
change in relatively
short time, why can’t major changes happen over thousands of
generations?

46.
Now you know what broccoli and Butterball turkeys have to do with evolution!
(Answers about oranges to come in this slide show!)
THINK ABOUT IT

47. How Do We Know Evolution Happens?
The Fossil Record
provides evidence that
organisms have changed
over time.

48. If evolution has happened, we should be able to find evidence of evolution in the fossil record AND WE HAVE !
BBC Tiktaalik video

49. Lots of TRANSITIONAL FOSSILS have been found
Scientific American; Dec 2005; Vol 293; p

50. TIK-TAALIK Intermediate between fish and early tetrapods
TIK-TAALIK
Intermediate between fish and early tetrapods
Fins have basic wrist bones and simple fingers
Earliest fish with a neck
Discovered by Neil Shubin and Ted Daeschler in 2004

51. GEOGRAPHIC DISTRIBUTION = BIOGEOGRAPHY
If Darwin’s theory is correct you would expect to find closely related yet different species living in a
geographic region as they spread into nearby habitats and evolve.
That’s EXACTLY what we do see!

52. The beaks of Galapagos finches have
GALAPAGOS FINCHES
The beaks of Galapagos finches have
adapted to eating a variety of foods

53. GALAPAGOS TORTOISES Tortoises adapted to different habitats as they
GALAPAGOS TORTOISES
Intermediate vegetation Intermediate necks
Little vegetation Long necks
Image from: BIOLOGY by Miller and Levine; Prentice Hall Publisher©2006
Lots of vegetation Short necks
Tortoises adapted to different habitats as they
spread from the mainland to the different islands.
= DIVERGENT EVOLUTION = ADAPTIVE RADIATION

54. If Darwin’s theory is correct you would also expect to find different species living in far apart geographic regions
but similar habitats becoming more alike as they adapt to similar environments.
That’s EXACTLY what we do see!

55. BOTH LIVE IN FOREST ECOSYSTEMS
Adapted to similar environments, but evolved independently from different ancestors.
SUGAR GLIDER in Australia is a marsupial more closely related to Kangaroos than North American
FLYING SQUIRRELS because its ancestors were marsupials.

56. Whales and sharks have a similar body design
Whales and sharks have a similar body design
even though they are very different organisms
(one is a fish; the other, a mammal)
because they have independently adapted to living in a similar environment.
= CONVERGENT EVOLUTION

57. HOMOLOGOUS STRUCTURES-Forelimbs of all mammals share same arrangement of bones that can be traced to same embryological origin
BIOLOGY by Campbell and Reece Prentice Hall Publishing©2005

58. EVOLUTION explains why certain
characteristics in related species have an
underlying similarity.
Section 15-3
Turtle
Alligator
Bird
Mammal
Ancient lobe-finned fish

59. amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds, reptiles, and mammals, which lines the chorion and contains the fetus and the amniotic fluid

60. VESTIGIAL ORGANS
Some homologous structures are vestigial and have no useful function even though they are still present.
Examples:
Hipbones and pelvis in whales and boa constrictors
Cecum (appendix) in humans Skink legs

61. Most mammals have a pouch between their small and large intestine that contains bacteria to digest plants called a cecum.
In humans the cecum
is shrunken and unused.
It is our appendix

62. EMBRYOLOGY Development of vertebrate embryos follows same path
Image from:

63. Same groups of undifferentiated cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all evolved from a common ancestor.
Image from:

64. Why grow a tail and then lose it?
HUMAN EMBRYO has a tail at 4 weeks which disappears at 8 weeks
Pharyngeal pouches
become gills in fish,
parts of throat/ears in humans

65. Nonfunctional legs in skinks
Why would an organism possess organs without function?
Why would an organism grow a part and then discard it?
If organisms evolved from ancestors in which that
part functioned, the gene code to make the part would still be there even though it doesn’t work.
If the organ is not vital to survival, then
natural selection would not cause its elimination.

66. MOLECULAR HOMOLOGIES
All life forms share same genetic machinery (DNA & RNA)
Universal genetic code
Important genes share highly conserved sequences

67. Similarities in protein sequences suggests similarities in DNA
Image from: Modern Biology by Holt, Rinehart, and Winston

68. DNA and protein sequences
MOLECULAR HOMOLOGIES
Similarities in
DNA and protein sequences
suggest
relatedness
Image from: BIOLOGY AP EDITION by Campbell and Reece; Prentice Hall Publishing©2005

69. Similarities in karyotypes suggest an evolutionary relationship
Human- 46 chromosomes Chimpanzee- 48 chromosomes
Similarities in karyotypes
suggest an evolutionary relationship
Human:
Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

70. Even differences show relatedness
Human- 46 chromosomes Chimpanzee- 48 chromosomes
Even differences show relatedness
Chimpanzees have 2 smaller chromosome pairs we don’t have
Humans have 1 larger chromosome pair (#2) they don’t have.
Human:
Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

71. PSEUDOGENES are vestigial genes.
EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are nonfunctional.

72. Slide by Kim Foglia@ http://www.explorebiology.com/

73. Why does evolution matter now?
EX: Changes in disease-causing microbes that produce new organisms and new diseases.
_______
___
__________________________
Can see Natural selection happen
Bird flu
HIV
Antibiotic-resistant tuberculosis
Why does evolution matter now?

74. Researchers have developed numerous drugs to combat HIV
But using these medications selects for viruses resistant to the drugs
Patient
No. 1
Patient No. 2
Percent of HIV resistant to 3TC
Patient No. 3
Weeks
Graph from BIOLOGY by Campbell and Reece

75. Slide by Kim Foglia@www.biologyzone.com