Evolution of Life

2. State Standard
SB5C. Explain how fossil and biochemical
evidence support the theory
Evidence of Evolution (15.2)

3. 15.2 Evidence of Evolution
The Fossil Record
Evolution
 Fossils provide a partial record of species that lived
long ago.
 Only the harder parts of an organism are likely to
leave fossils – ex: shells, bones, thick cell walls.
 Very few fossils capture the details of skin or internal
organs.
 Sometimes impressions are left behind in sediments
along rivers and lakes.
Chapter 15

4. 15.2 Evidence of Evolution
The Fossil Record cont’d
Evolution
Glyptodont
 Fossils show that ancient species share similarities with
species that now live on Earth.
 One problem w/ the fossil record is the lack of
“intermediate” or transition forms. This could be due to
many organisms being too soft or due to fossils being
destroyed by the erosion or pressure.
Armadillo
Chapter 15

5. Fossils Cont’d
Otzi the Iceman

6. Fossils Cont’d

8. 15.2 Evidence of Evolution
Determining Fossil Age
Evolution
 Biologists use radioisotope (radiometric) dating to
determine the approximate age of fossils.
 The isotopes act as clocks for measuring time.
 To use this method, scientists must know:
1. The half-life of the isotope being measured.
2. how much of the isotope was originally present in the
fossil or in the rock containing the fossil.
3. how much of the isotope is left..
 Half-life is the amount of time it takes for half of the isotope
to decay.
Chapter 15

9. 15.2 Evidence of Evolution
Determining Fossil Age Cont’d
Evolution
 Biologists most often use
Carbon 14 for radioisotope
dating, but its half-life is
relatively short.
 Other isotopes like Uraniaum
235 are often used to help
determine the age of older
fossils.
 Relative dating determines the
relative age of rocks/fossils by
comparing them to known older
or younger layers.
Chapter 15

10. Evolution
 Common ancestry
can be seen in the
complex metabolic
molecules that many
different organisms
share.
Comparative Biochemistry
15.2 Evidence of Evolution
Chapter 15

11. Evolution
 Comparisons of the similarities in these
molecules across species reflect evolutionary
patterns seen in comparative anatomy and in
the fossil record.
 Organisms with closely related
morphological features have more closely
related molecular features.
15.2 Evidence of Evolution
Chapter 15
Comparative Biochemistry Cont’d

12. Evolution
 Vertebrate embryos exhibit homologous
structures during certain phases of
development but become totally different
structures in the adult forms.
 Many scientists believe this is evidence that all
vertebrates share a common ancestor.
Comparative Embryology
15.2 Evidence of Evolution
Chapter 15

13. Evolution
15.2 Evidence of Evolution
Chapter 15
Anatomical Evidence
Homologous Structures
• Anatomically similar
structures that may or
may not have the same
function.
• Indicate possible
common ancestry

14. Evolution
 Show that
functionally similar
features can evolve
independently in
similar
environments
 Similar in function but not in
construction so they do not
indicate shared ancestry
15.2 Evidence of Evolution
Chapter 15
Anatomical Evidence
Analogous Structures

15. Evolution
Anatomical Evidence
Vestigial Structures
 Structures that are the
reduced forms of
functional structures in
other organisms.
15.2 Evidence of Evolution
Chapter 15
 Evolutionary theory
predicts that features of ancestors that no
longer have a function for that species will
become smaller over time until they are lost.

16. Anatomical Evidence
Vestigial Structures Cont’d

17. Evolution
Anatomical Evidence
Adaptations
 An adaptation is an inherited trait that
may increase an organism’s survival and
reproductive success.
 Fitness is a measure of the relative
contribution an individual trait makes to the
next generation.
15.2 Evidence of Evolution
Chapter 15

18. Evolution
Camouflage
 Allows
organisms to
become almost
invisible to
predators
 All about hiding
Leafy sea dragon
Chapter 15
Anatomical Evidence
Adaptations Cont’d

19. Camouflage Cont’d

20. Camouflage Cont’d

21. Evolution
Mimicry
 One species evolves to resemble another
species.
 All about scaring/warning (not hiding).
Western coral snake California kingsnake
Chapter 15
Anatomical Evidence
Adaptations Cont’d

22. Mimicry Cont’d

23. Geographic Distribution
Evolution
 The distribution of plants and animals that
Darwin saw first suggested evolution to Darwin.
Rabbit Mara
15.2 Evidence of Evolution
Chapter 15

24. Geographic Distribution Cont’d
Evolution
 The Mara & Rabbit fill the same niche on 2
different continents.
 Darwin observed that the Mara was more
similar to other South American species than it
was to the rabbit, and vice versa.
Rabbit Mara
15.2 Evidence of Evolution
Chapter 15

25. 15.2 Evidence of Evolution
Phylogenetic Trees
Evolution
 A phylogeny is a description of
the line of descent of a group of
organisms.
 Fossil collections are often not
complete enough to determine
any evolutionary patterns or
traits, so biologists will infer
likely phylogenies by comparing
morphological features, DNA
sequences, and chromosomal
characteristics.
 Extinction is the permanent
loss of a species.
Chapter 15

26. Evolution
 Derived traits are newly evolved features,
such as feathers, that do not appear in the
fossils of common ancestors.
 Ancestral traits are more primitive features,
such as teeth and tails, that do appear in
ancestral forms.
15.2 Evidence of Evolution
Chapter 15
Types of Characters (traits)

27. Cladogram - a
diagram showing
possible
relationships
between
organisms based
on shared traits
(characters)

28. How to Read – if
the organism is
above the trait, it
has the trait. If it
is below the trait,
it doesn’t have it.

29. Ancestral
Character –
shared by all
species on the
diagram.
Derived
Character- only
shared by some
Outgroup – least
in common

31. Bat Wing
Human Arm
Homologous or Analogous?

32. Bat Wing
Bird Wing
Homologous or Analogous?

33. Dragonfly Wing
Hummingbird Wing
Homologous or Analogous?

34. Dragonfly Wing
Bumblebee Wing
Homologous or Analogous?

35. 1. A
2. B
3. C
4. D
A
B
C
D
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Chapter Diagnostic
Questions
A. ancestral traits
B. analogous structures
C. homologous structures
D. vestigial structures
Identify the term that is used to describe
anatomically similar structures inherited from
a common ancestor.
Evolution
Chapter 15

36. 1. A
2. B
3. C
4. D
A
B
C
D
0% 0%
0%
0%
Chapter Diagnostic
Questions
A. snake pelvis
B. Kiwi wings
C. porpoise flipper
D. human appendix
Which is not a vestigial structure?
Evolution
Chapter 15
Kiwi Bird

37. 1. A
2. B
3. C
4. D
A
B
C
D
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0%
0%
Evolution
Chapter 15
15.2 Formative
Questions
A. a tail
B. bones
C. feathers
D. teeth
Which is an example of a derived trait?

38. 1. A
2. B
3. C
4. D
A
B
C
D
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0%
0%
Evolution
Chapter 15
15.2 Formative
Questions
A. analogous structures
B. embryological structures
C. homologous structures
D. vestigial structures
Which features are similar in use and evolve in
similar environments, but do not evolve from a
common ancestor?

39. 1. A
2. B
A
B
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0%
Evolution
Chapter 15
15.2 Formative
Questions
Organisms with similar
anatomy share similar
DNA sequences.
A. True
B. False

40. 1. A
2. B
3. C
4. D
A
B
C
D
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0%
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Evolution
Chapter 15
15.2 Formative
Questions
A. adaptation
B. biogeography
C. gradualism
D. speciation
At the heart of the theory of evolution by natural
selection lies the concept of __________.

41. 1. A
2. B
3. C
4. D
A
B
C
D
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Evolution
Chapter 15
Standardized Test
Practice
Which is the best explanation
for the similarities in the
construction of these forelimbs?
A. Each forelimb is a similar
modification derived from a
different ancestor.
B. Natural selection has
produced similar modifications
in the forelimb.
C. They are functionally similar
features that have evolved
independently.
D. They are modifications of the
forelimbs of a common ancestor.

42. 1. A
2. B
3. C
4. D
A
B
C
D
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0%
0%
Evolution
Chapter 15
Standardized Test
Practice
A. camouflage
B. fitness
C. mimicry
D. resemblance
Predators learn to avoid monarch butterflies because
they contain a poison that is distasteful and can cause
the predator to get sick. The viceroy butterfly finds
protection by closely resembling the monarch. What is
this adaptation in the viceroy called?