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

3. Chapter 15
Evolution
15.2 Evidence of Evolution
The Fossil Record
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.

4. The Fossil Record cont’d
Chapter 15
Evolution
15.2 Evidence of Evolution
The Fossil Record cont’d
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.
Glyptodont
Armadillo

5. Fossils Cont’d
Otzi the Iceman

6. Fossils Cont’d

8. Determining Fossil Age
Chapter 15
Evolution
15.2 Evidence of Evolution
Determining Fossil Age
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.

9. Determining Fossil Age Cont’d
Chapter 15
Evolution
15.2 Evidence of Evolution
Determining Fossil Age Cont’d
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.

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

11. Chapter 15
Evolution
15.2 Evidence of Evolution
Comparative Biochemistry Cont’d
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.

12. Chapter 15
Evolution
15.2 Evidence of Evolution
Comparative Embryology
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.

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

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

15. predicts that features of ancestors that no
Chapter 15
Evolution
15.2 Evidence of Evolution
Anatomical Evidence
Vestigial Structures
Structures that are the reduced forms of functional structures in other organisms.
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. Chapter 15
Evolution
15.2 Evidence of 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.

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

19. Camouflage Cont’d

20. Camouflage Cont’d

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

22. Mimicry Cont’d

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

24. The Mara & Rabbit fill the same niche on 2 different continents.
Chapter 15
Evolution
15.2 Evidence of Evolution
Geographic Distribution Cont’d
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.
Mara
Rabbit

25. Chapter 15
Evolution
15.2 Evidence of 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.
Phylogenetic Trees

26. Chapter 15
Evolution
15.2 Evidence of Evolution
Types of Characters (traits)
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.

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
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. Homologous or Analogous?
Bat Wing
Human Arm

32. Homologous or Analogous?
Bat Wing
Bird Wing

33. Homologous or Analogous?
Dragonfly Wing
Hummingbird Wing

34. Homologous or Analogous?
Dragonfly Wing
Bumblebee Wing

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

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

37. Which is an example of a derived trait?
Chapter 15
Evolution
15.2 Formative Questions
Which is an example of a derived trait?
a tail
bones
feathers
teeth A B C D
FQ 6

38. Which features are similar in use and evolve in
Chapter 15
Evolution
15.2 Formative Questions
Which features are similar in use and evolve in
similar environments, but do not evolve from a
common ancestor?
analogous structures
embryological structures
homologous structures
vestigial structures A B C D
FQ 7

39. Organisms with similar anatomy share similar DNA sequences.
Chapter 15
Evolution
15.2 Formative Questions
Organisms with similar anatomy share similar DNA sequences.
True
False A B
FQ 8

40. At the heart of the theory of evolution by natural
Chapter 15
Evolution
15.2 Formative Questions
At the heart of the theory of evolution by natural
selection lies the concept of __________.
adaptation
biogeography
gradualism
speciation A B C D
FQ 9

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

42. Standardized Test Practice
Chapter 15
Evolution
Standardized Test Practice
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?
camouflage
fitness
mimicry
resemblance A B C D
STP 3