This document provides an overview of chapters 16 & 17 which cover the evolution of populations, the history of life, and key figures and concepts in evolutionary theory. It discusses how genes make evolution possible through genetic variation from mutations and gene recombination. Natural selection and genetic drift are described as causes of a population's gene pool changing over time, which can lead to the formation of new species through reproductive isolation. Fossils are examined as evidence for evolution and mass extinctions. Patterns in the fossil record show most species have become extinct, fossils are found in a particular order, and organisms have changed over time. Evolution occurs through both gradualism and punctuated equilibrium.

1. Chapters 16 & 17
Evolution of Populations and
The History of Life

2. Evolution of Populations
• EQ: How can populations evolve to form
new species?
– How do genes make evolution possible?
– What causes a population’s gene pool to
change?
-- How do new species form?

3. Background and Review:
How are evolution and
genetics related?

4. Jean-Baptiste Lamarck
He was the first to propose how organisms
could change over time.

5. Theory of Acquired Characteristics
• Theory that organisms’ selective use and disuse
of organs led to acquiring or losing certain traits
in their lifetime.
• These traits could then be passed on to their
offspring
• Ex) giraffe stretching to get leaves = neck gets
longer over time….pass longer neck on to
offspring (incorrect)

6. Darwin
Proposed the mechanism of NATURAL
SELECTION to explain the observable
patterns of evolution

7. Darwin
On what concept was this work based?
Observations
• Members of a population often vary greatly in
their triats
• Traits are inherited from parents to offspring
• All species are capable of producing more
offspring that their environment can support

8. Darwin
On what concept was this work based?
Inferences
• Individuals whose inherited traits give
them a higher probability of surviving and
reproducing in a given environment tend
to leave more offspring than other
individuals
• This unequal ability of individuals to
survive and reproduce will lead to the
accumulation of favorable traits in the
population over generations.

9. Genetics & Evolution
• Scientists discovered that heritable traits
are determined by DNA (genes on
chromosomes).
• Later they realized that changes in the
DNA (mutations) and gene recombination
through sexual reproduction results in
variations; thus, further relating Darwin
and Mendel’s original work.

10. Evolution acts on ______________________ not on individuals.
Example: Black lizards are able to absorb more heat on cold days.
The extra heat allows
them to move more quickly on cold days which makes
them better able to
avoid predators. The allele for black body would
increases an individuals
fitness and they would leave more offspring that other
lizards. The relative
frequency of the allele for black body could, therefore
increase.

11. How do genes make
evolution possible

12. Two main sources of
genetic variation
1. Mutations—change in genes (DNA
sequence) or chromosomes
2. Gene recombination—mixing of
genes that result from:
A. meiosis
B. sexual reproduction

13. What causes a population’s
gene pool to change?

14. Gene Pool
The combined genetic information of all the
members of a particular population

15. Selection processes
Stabilizing-natural selection in which
intermediate phenotypes survive more
successfully than do extreme phenotypes

16. Selection processes
Directional- natural selection in which
individuals at one end of the phenotypic
range survive more successfully than do
other individuals.

17. Selection processes
Disruptive-natural selection in which
individuals on both extremes of a
phenotypic range survive more
successfully than do individuals with
intermediate phenotypes

18. Selection Curves

20. How do new species
form?

21. Species
• A group of similar organisms that can
breed and produce fertile offspring

22. Genetic Drift
Random change in allele frequencies that
occur in small populations

25. Speciation
Formation of a new species through
reproductive isolation
Example: Galapagos Island finches and
tortoises

26. Darwin’s Galapagos Island
finches

27. Three types of reproductive
isolation
1. Behavioral isolation (sounds or display rituals)
2. Temporal isolation (nocturnal vs. diurnal)
3. Geographical isolation (separated by oceans or
mountain ranges)
If one of the Earth’s plates moves 1.9 cm a yr., in 1 million years it
would move 12 miles

28. Geographical Isolation

29. Allopatric Speciation
Gr. other + fatherland
The formation of new
species in populations
that are geographically
isolated.
Ex: mountains, canyons,
or oceans

30. Sympatric Speciation
Gr. together + fatherland
Formation of a
new species in
populations that
live in the same
geographic area.

32. Behavior
A way an organism reacts to changes in
its internal condition or external
environment

33. Migration
Periodic movement and return of animals
from one place to another. Organisms that
migrate have an advantage over one’s
that do not.

34. Migration
• Example:
• 1. Monarch Butterfly
• http://video.pbs.org/video/1063682334 (2min)
• 2. Salmon
• To the left:
• Pink
• salmon
• moving
• upstream.

35. Courtship
Type of behavior in which an animal sends
out stimuli in order to attract a member of
the opposite sex.
30 Minute Mark:
http://www.pbs.org/wnet/nature/episodes/what-males-will-do/video-fullepisode/5374/
http://www.pbs.org/wnet/nature/video/what-males-will-do-video-spidercourtship-dance/956/

36. Social Behavior
The interaction of members with their own
species in a way to increase the fitness of
all members.
Ex: packs, colonies, hives, troops

37. Chapter 17
The History of Life

38. EQ: How do fossils help biologists
understand the history of life on Earth:
– How do scientists use fossils to study Earth’s
history?
– What are some patterns in which evolution
has occurred?
– How fast does evolution take place?

39. Earth’s Early Atmosphere
• Over time photosynthetic bacteria became
common in the sea which started adding
oxygen to the atmosphere
• Next, oxygen gas started accumulating in
the atmosphere which decreased the
hydrogen sulfide and methane and
eliminating most anaerobic organism but
increased aerobic organisms

40. • The ozone layer started to form to provide
protection from ultraviolet rays
• Some organisms evolved ways of using
oxygen for respiration and greater energy
production
• With more energy available, eukaryotes
evolved in the sea and then on land
• The eukaryotic cells aggregated into
multicellular organisms and the evolution
of the diversity of life was well on its way

41. Miller and Urey Experiment
Carl Sagan Explains Miller-Urey Experiment:
http://www.youtube.com/watch?v=79o6xzMfzKg
Miller-Urey Experiment Animation:
http://www.youtube.com/watch?v=iahBQolXQH8
**Mixtures of the organic compunds necessary
for life could have arisen from simpler
compounds on present on a primitive Earth.
**Found that life arose from non-life. Is this
true?

42. Fossil
• Preserved remains of ancient organisms
• http://www.neok12.com/php/watch.php?
v=zX076e0e6d5a7b775b0d7a41&t=Fossil
s

43. Fossil Record
Information about past life that has been
obtained from fossils

45. 1. Most organisms that have
ever lived are now extinct
2. fossils occur in a particular
order in the rock layer
3. groups of organisms have
changed over time

46. Extinct
A species that has completely died out
Extant
Species that still survive

48. Where do most fossils
form?
Most fossils form in sedimentary
rock as weight compresses layers
of sediment in bodies of water

50. • Not all parts of animals become fossilized.
• Fossilization activity

51. http://www.ucmp.berkeley.edu/education/e
xplorations/tours/fossil/5to8/Intro.html

52. What are some patterns
in which evolution has
occurred?

53. Mass Extinction
Many types of living things become extinct
in a short period of time
Ex: Dinosaurs
Asteroid hitting Earth at Chicxulub Mexico
on the Yucatan peninsula
?????
http://www.neok12.com/php/watch.php?
v=zX060c4178075b5f7f7e6663&t=Prehist
oric-Animals

54. How fast does
evolution take place?

55. Gradualism
A model of evolution which theorizes that
most speciation is slow, uniform and
gradual.

57. Punctuated Equilibrium
Long period in which a species undergoes
little to no change, interrupted by relatively
brief periods of sudden change

58. Catastrophism
The principle that events in the past
occurred suddenly and were caused by
different mechanisms than those
operating today