1. 9.5 Evidence for Evolution
Unit 9: Evolution
9.5 Evidence for Evolution

2. Evidence of Evolution Fossil Record Evidence Comparative Anatomy
Vestigial Structures
Biochemistry
Embryology
Bacterial Resistance

3. Fossil Record
Fossils show that life has been changing over time.

4. Fossil Record
Transitional Fossils: show the progression from one species to the next.
Missing Links: show the intermediate states between an ancestral form and its descendants.
Example: Whales

6. Comparative Anatomy
Investigates the similarities and difference among organisms in bone structure and in other parts of the body.

7. Comparative Anatomy
Homologous structures: similar structures that share a similar origin but may not share similar function
Example: Human, cats, whales and bats share many of the same bones- humorous, ulna, radius, carpals
Analogous structures: structures that have similar function by not a similar origin are NOT EVIDENCE FOR A COMMON ANCESTOR.

8. Question
1. If two species have very similar anatomy and uses, what do we know about their evolutionary relationship?
2. Based on what the organisms use their bones for, which of the following organisms are probably the most closely related? The least?

9. Vestigial Structures
Structures present but reduced in size and have no use or less important function.
The species no longer needs the feature.
Example: Pythons have tiny femurs (leg bones)

10. Biochemistry
Comparisons of DNA of different species can used to establish evolutionary relationships.
DNA is the universal language for making proteins.
All proteins made using just 20 amino acids.
Similar DNA among species is evidence they decent from a common ancestor
Example: humans and chimps share 98.8% of their DNA!

12. Question Which two organisms are more closely related?
What two organisms are most distantly related?

13. Embryology
Studies the development of gametes, fertilization, and development in embryos and fetuses.
Similar larvae, different adult body forms
Similar embryos, diverse organisms
Show common ancestry

14. Bacterial Resistance
Antibiotic resistance is a consequence of evolution via natural selection
Antibiotic action is an environmental pressure
Bacteria which have a mutation allowing them to survive will live on to reproduce
Reproducing bacteria pass the trait to their offspring, which may result in fully resistant generation

17. Question
Why do you think it is important to take ALL of the antibiotics prescribed by your doctor?