1. AIM: How do comparative studies help trace evolution?

3. How do we know we are related to chimps & gorillas?
COMMON ANCESTOR

4. Comparative Studies Study of similarities between living things.
Provides evidence of a common origin (ancestor)

5. Why do scientists do comparative studies?
To observe how closely organisms are related to each other and see evolutionary patterns

6. COMPARATIVE STUDIES
Who are we closely related to?
Who are we distantly related to?

7. Types of Comparative Studies
Anatomy
Embryology
Biochemistry
DNA and Proteins

8. Comparative Anatomy What is anatomy?
What do you think comparative anatomy studies?
Study of structural similarities and differences in living things

9. HOMOLOGOUS STRUCTURES
Do you see any similarities between these organisms?
How are they similar? How are they different?
Homologous Structures - similar structures, different form & function. Shows evolutionary relationships (they are related).

10. VESTIGIAL ORGANS
The appendix and the tail bone are both VESTIGIAL organs. What do they have in common?
Vestigial structures- have no function.
Why would an organism possess organs with little or no function?
They are remnants of structures that may have had important functions in ancestral species, but no clear function in modern descendants.
Hind leg in whales

11. ANALOGOUS STRUCTURES
What do these two images have in common?
Insect Wing
Analogous Structures- similar form and function, different internal structure. Does not show evolutionary relationships.

12. Divergent vs. Convergent Evolution:
Divergent Evolution- the pattern of evolution in which
species that were once similar to an ancestral species
become increasingly different.
Convergent Evolution- the
pattern of evolution in which
distantly related organisms
evolve similar traits.

13. When do each of these types of evolution occur?
Divergent Evolution occurs when populations change
as they adapt to different environmental conditions.
Once related species now look different.
Convergent Evolution occurs when unrelated species
occupy similar environments in different parts of the
world. Unrelated species now look the same.

14. gorilla, fish and rabbit?
Which is Which?
Which is the
gorilla, fish and rabbit?

15. Comparative Embryology
In Comparative Embryology, related organisms show similar embryonic development

16. Comparative Biochemistry
Comparative Biochemistry compares the DNA or Amino Acids of an organism in order to find relationships among living things.
The more similar the DNA and Amino Acids, the more closely the two organisms are related.

17. Common Ancestor COMMON ANCESTRY This evidence leads to the idea of:
All species living and extinct were derived from common ancestors.

18. The Results of Genetic Variation:
Structural Change- the physical
features of an organism.
Functional Change- molecular or biochemical
changes affect how an organism works. Changes in
DNA often lead to functional changes.
Behavioral Change- many of the
specific behaviors today have become
common because they have resulted
in greater reproductive success.