1. Diversity
and
Evolution
SC.912.L.151
SC.912.L.15.10
SC.912.N.1.3
SC.912.N.2.1
SC.912.L.15.8

2. Origins of Life on Earth

3. Original Conditions on
Primitive Earth to make
life….
• Presence of liquid water
• Moderate temperature range
• Free oxygen in the atmosphere
• Adequate sunlight
• Absence of toxic substances in
atmosphere
• Absence of lethal radiation

4. Volcanoes Play a BIG Role
• Water vapor (eventually condensed and fell as
RAIN)
• Methane
• Hydrogen
• Nitrogen
• Ammonia
• Carbon Dioxide (we now have oxygen b/c of
photosynthetic bacteria)
• Carbon Monoxide

5. Earth History
• Evolution is studied using concepts about earth history. The
earth is between 4.3 and 4.5 billion years old.
• Approximately 3.9 billion years ago, the surface was likely
cool enough for water vapor to condense and form oceans
• Geological evidence suggests that cells similar to modern
bacteria were common 3.8 billion years ago.

6. How did life on Earth begin?
Until the 1700’s people believed that
living things could come from nonliving
substances, spontaneous generation.

7. Spontaneous generation: Pasteur’s
experiment
• Experiment: Pasteur filled a flask with broth with a long S shaped neck.
He boiled it to kill all life. It was open and exposed to air, but anything in
the air got stuck on the curves of the neck.
• Conclusion: Spontaneous generation was disproved and biogenesis
theory was substantiated. Contamination came from other
microorganisms, not ―air‖.
QUESTIONS
• What was the hypothesis? What was the experimental group? The
control group? The constants? The variable?

8. Theory of Chemical Evolution
“Primordial Soup Theory”
• Conditions on the early Earth were
very different.
• The atmosphere had no oxygen
• Energy sources, such as lightning, volcanic activity, and ultraviolet
sunlight (no ozone layer)

9. Chemical Evolution
• Earth’s early atmosphere: HCN, CO2, CO, N, H, S, H2O
• “Life arose from the oceans”
• He believed that energy from lightning and the sun can
spark chemical reactions to create AMINO ACIDS that made
proteins.

10. Chemical Evolution
Urey and Miller
• created in the
laboratory, th
e conditions of
early Earth.
• They
discharged
sparks in an
“atmosphere”
of the Miller-
Urey model
consisted of
H2O, H2, CH4, and
NH3 gases.
• produced a
variety of

11. Chemical Evolution
• Alternate sites proposed for the synthesis of organic
molecules include
• submerged volcanoes and deep-sea vents where
hot water and minerals gush into the deep ocean.

12. Prokaryotes
• Prokaryotes were the earliest
organisms on Earth and evolved
alone for 1.5 billion years.
• two prokaryotic domains:
Bacteria and Archaea

13. Prokaryotes
„ have a cell wall
external to the
cell membrane
• Lack membrane bound
nuclues and organelles
• Double-stranded DNA
molecule is in a single
ring shaped

14. OXYGEN The evidence of oxygen gas
• ATMOSPHERE
Remember the atmosphere of
formation can be seen in rocks
when layers of iron oxide on the
early Earth was made up of bottoms of oceans stopped
nitrogen, carbon forming when oxygen appeared.
dioxide, water vapor, but no
free oxygen
• Oxygen comes from
photosynthesis when leaving
oxygen gas.
• About 2 billion years ago, the Cyanobacteria created the
oxygen level in the oxygen in the atmosphere.
atmosphere started to rise.
• Aerobic metabolism, much
more efficient than
anaerobic, became possible.
Question

16. Evolution
• Process by which species of organisms
change over time
• Thing evolve around us all the time
• Based on scientific evidence such as…
– Fossils
– Comparative morphology/anatomy of
organisms
– Embryology
– Analysis of genetic material (DNA
analysis…DNA fingerprinting!)

17. Terms to Know
• Species
– a group of organisms that
share similar
characteristics and can
interbreed to produce
fertile offspring
– As species EVOLVE, they
produce new traits and lose
other traits….
• Adaptation
– Any physical or behavioral
trait that improves an
organisms chance for

18. Fossil Evidence
• Fossils: Evolution
for
– Remains or evidence of
organisms that have lived in the
past
– Provided clues of when
different species lived
• Law of Superposition
– States that in undisturbed
sedimentary rock, older rock
layers lie beneath younger
rock layers
– By Identifying the fossils
indifferent layers of rock and
applying the law of

20. Law of
Superposition

21. Biogeography
• Study of the distribution of
Earth’s organisms
• Continental Drift Hypothesis
– States that the continents
were once joined in a
single, large landmass called
PANGAEA
– Pangaea broke up over
millions of years and
continents ended up where
they are today

23. Comparative
Anatomy/Morpholog
y
• Do other organisms have
arms like us?
• Many species share
similar structures..
• Do flamingos and blue
jays have feathers?
– Yes…the presence of
feathers suggest that both
groups of birds descended
from an animal with
feathers
– Flamingos and blue jays

24. Homologous
Structures
• Body parts of
different
organisms that
have similar
structure but NOT
similar FUNCTION
• Homologous
structures DO
indicate shared
ancestor

25. Analogous Structures
• Body parts that have a SIMIALR FUNCTION
but NOT similar structure
• Body parts with Different
structure, same function
• Do NOT indicate shared ancestry
• An analogous structure found in two
different species

28. Homologous vs.
Analogous Structures
• Homologous= Same
structure, DIFFERENT Function
• Analogous= Different
Structure, SAME Function

29. Comparative Anatomy
Anatomical features that are
similar in structure are
called homologous
structures, and they
indicate common ancestry.

30. Vestigial Structures
• Structures that do not seem
to play a role in the body
functions of the organism
– Appendix
• Rats digestion
• Humans no use…appendix is a
vestigial structure
• It can be concluded that the
common ancestor of the human and
rat had an appendix

31. Embryology
• Study of embryos
• Embryo early stage in the
development of an organism
• Scientists compare the
development of the embryos
of different species
• Similarities in development
=shared ancestor
• More traits in common=more
closely related
Modern Organisms
EVOLVED from
COMMON

33. Chemical Evidence
of Evolution
• Chemicals found in living
things also provide
clues to ancestry..what
chemical?
– DNA!!!
• Comparisons of the
sequences of the
nucleotides in DNA and
the amino acids in
certain proteins can
also be used to show
more common ancestry
• More similarities in two

35. ALL organisms have DNA made up of the
same Amino Acids…
The only thing that’s different is the
ARRANGEMENT/sequence of amino
acids…
The More similar AA sequences= the
more closely related the organisms are!

36. Similarities in Molecular
Biology
Common amino acid sequences suggest an
evolutionary relationships between various
species of organisms.

37. Observed Evolutionary
• Speciation
Change
– Evolution of a new species from an
existing species
• Occurs when a population is
separated into groups that cannot
reach each other to interbreed
• Once groups are
separated, environmental
conditions in each area influence
which traits are helpful or harmful
to members of each population
– Less helpful traits disappear
– Helpful traits become more popular
• Overtime, these changes can produce
2 distinct species that can no longer
interbreed

41. Two Ways Evolution is
believed to have
• Gradualism
Occurred
– Evolution occurring over a long
period of time
– Slow and constant change
– Small difference between
generations
– This is how Darwin believed
NATURAL SELECTION worked
• Punctuated Equilibrium
– Evolution occurs in spurts
– Changes occur rapidly followed by
long period without change
– Causes:

42. Microevolution
• When evolution occurs quickly
enough for scientists to
observe
• Bacteria
– Reproduce rapidly
– Trait for Resistance to
antibiotics is passed down to
offspring
– This is how bacteria become
resistant to certain
medicines…NOT GOOD

43. Convergent evolution
• organisms that
descended from
different ancestors
• Evolve similar
anatomies and/ or
behaviors if they live in
similar environments

44. • Organisms Divergent
from the
same Evolution
ancestor
have
developed
different
anatomies/be
haviors (and
eventually
form new
species)
• Environment
influences
their new

45. Darwin’s Theory of Evolution
by Natural Selection

46. Ideas that
shaped Darwin
– Before Darwin people believed Earth was
less than 10,000 years old and also
relatively unchanged
• Buffon- Studied the fossil record which showed that the Earth
might be much older.(4.3 and 4.5 billion years old)
• Hutton - Layers of rock are moved by forces
beneath Earth’s surface. Most geological
processes operate extremely slowly.
• Lyell - geologic process that shaped the Earth in the past still
continue today.

47. Ideas that shaped Darwin
Before Darwin people believed that species were fixed, plants
and animals had always been the way they are today
Cuvier – based fossils from different rock layers gave evidence
that organisms from the past differed greatly from living species,

48. Ideas that shaped Darwin
•
Lamarch’s
Use or disuse
1st to suggest that species change
evolve or evolve over time.
But his explanation was flawed.
He thought characteristics acquired
through your life could be passed
down from parent to offspring.

49. • Malthus – suggested that if the human population continued
to grow unchecked, eventually there wouldn’t be enough food
and living space for everyone.

50. • As Malthus
predicted, worl
d population
growth is
exponential:
• 1 billion in 1830
• 2 billion in 1930
• 3 billion in 1960
• 4 billion in 1974
• 5 billion in 1987
• 6 billion in 1999
• 7 billion in 2013

51. Voyage of the Beagle
• Darwin made a voyage around the word collecting thousands of
plant and animal specimens.
• His observations and collected evidence led him to propose
hypothesis that living things change over time
• Theory of Evolution through natural selection.

52. Voyage of
the Beagle
• Darwin noticed that
plants and animals on
the Galapagos islands
of the coast of Ecuador
were different from
those on the mainland
and also from island
to island
• .

53. Neck-size vs. Vegetation
height

54. Galapagos’ Finches

55. Galapagos’ Finches

56. Darwin’s Theory
• In 1859, Darwin published a book titled,
• “On the Origin of Species”
• In this book he presented all the evidence he had gathered over
the past several years supporting his theory that evolution has
been taking place for millions of years—and continues in all
living things.
• In his book he also proposed a mechanism for evolution called
• Natural Selection

57. Summary of Evolution
• DNA is the blue-print for building ALL living things on
planet Earth.
• DNA sequences are changed by:
• random mutations
• Radiation
• Viruses
• Chemicals
• sexual reproduction
• Migration
• geological events
• As a result there is variation within populations of a
species.
• Those individuals of a particular species with a
phenotype (as a result of their genotype) that is
more fit to survive in a given environment has a
better chance to reproduce.

58. NATURAL SELECTION
The ability of an organism to survive and
reproduce in its specific environment is called
fitness.
• Individuals with characteristics that are not
well suited to their environment either die or
leave few offspring
• Individuals that are better suited to their
environment survive and reproduce most
successfully.
• Darwin called this process Survival of the
Fittest, or Natural Selection.

59. 4 Principles of Natural
Selection
• Variation
• Competition
• Excess offspring
• Survival of the Fittest

60. 4 Main Principles
of Natural
1. Selection
Variation exists
within a
population
2. Organisms
compete for
limited
resources
3. Organisms
produce more
offspring than
can actually
survive

61. • Three species of lizard.
• B- The ones at the bottom live in the shrubland, and
are colored to blend in.
•The top pictures show the
same species of lizard, but the
variety that lives in the White
Sands
•They all evolved to become
white (camouflage)
•The DNA on the bottom shows
the location of the mutation
that gives the white color

62. 1. Inherited Variation
Individual organisms within the population differ. Most of this
variation is determined by genetic inheritance (recombination), but
sometimes it is the result of genetic mutations.

63. 2. Struggle for Existence
Because so many offspring are produced, many will die due to a
lack of resources, predation, disease, or other unfavorable
conditions.

64. 3. Overproduction of Offspring
Organisms produce more offspring than can survive.
Many of the offspring do not survive to reproductive age.

65. 4. Differential Reproduction
Individuals best suited to their environment survive and reproduce
most successfully. Therefore these organisms pass their
advantageous traits to their offspring while offspring with
disadvantageous traits die or produce fewer offspring.

66. Descent with Modification
• Natural selection
causes species to
change over time.
• Species alive today
descended with
modification from
ancestral species.

67. Evolution of populations
• Genetic Drift
• Sometime changes in the allele
frequency within a population occur
by chance. This is called genetic drift.
Before After
• The genes of the next generation
will be the genes of the “lucky”
individuals, not necessarily the

68. Gene Flow
• the process of genes moving
from one population to
another. and emigration of organisms.
 For example:
 The immigration
 The dispersal of seeds or spores.