1. Darwin’s Ideas

2. Inherited Variation
In talking with farmers, Darwin found that different animals had different traits.
Some cows produced a lot of milk; others produced more meat
Farmers had bred vegetables into many different strains

3. Artificial Selection
The process by which humans breed animals and plants for traits that are desirable.

4. Evolution by Natural Selection
Three Main Ideas
The Struggle for Existence
Survival of the Fittest
Descent with Modification

5. The Struggle for Existence
There is not enough resources to support all organisms that are born
All species need to compete to get food, living space and other resources.

6. Survival of the Fittest
The organisms that are best suited for their environment will survive and produce offspring.
Fitness- the ability to survive and reproduce in an environment.

7. Survival of the Fittest
Adaptation- Any inherited characteristic that increases an organism’s chance of survival.
Brainstorm: What are some adaptations of local animals to our environment?

8. Survival of the Fittest
Natural Selection- The process by which organisms become more fit to their environment over time.

9. Descent with Modification
Species that exist today have descended from previous species that have changed over time.
Common Descent – all species were derived from common ancestors.

10. Evidence of Evolution- 1800’s
Fossil Record
Geographic Distribution of Living Species
Homologous Body Structures
Similarities in Embryology

11. Fossil Record As scientists found more fossils
Realized the earth was older than previously thought
Life was more diverse than previously thought
Found intermediate species that showed evolution between one species and the next

12. Geographic Distribution
Animals in different continents had different common ancestors so different species evolved.
The similarities were due to living in similar environments

13. Homologous Structures
Structures in animals that develop from the same embryonic tissues but have different mature forms.
Vestigial Organs- traces of homologous structures that don’t serve a known purpose
Appendix
Tailbone

14. Brainstorm: How has each of the bones shown above changed from animal to animal?

15. Similarities in Embryology
Early embryos of many animals with backbones look similar, although differences occur.

16. Who am I?
On the next slides, I will show you different embryos. You need to decide which of the animals you are looking at.

17. Am I a bat, cat or human?

18. Results:

19. Am I a chicken, a fish, a human, a rabbit, a salamander, or a turtle?

20. Results: