1. Chapter 4
Section 2
Evolution

2. Objectives Explain the process of evolution by natural selection.
Explain the concept of adaptation.
Describe the steps by which a population of insects becomes resistant to pesticide.

3. Evolution by Natural Selection
English naturalist, Charles Darwin observed that organisms in a population differ slightly from each other in form, function, and behavior
Differences are
hereditary

4. Evolution by Natural Selection
Charles Darwin in his book, Origin of Species, proposed that the environment exerts a strong influence over which individuals survive to produce offspring, and because of certain traits, some individuals are more likely to survive and reproduce than other individuals

5. Nature Selects

6. Evolution by Natural Selection
Natural selection - process by which individuals that have favorable variations and are better able to survive and reproduce in their environment
Evolution - change in the characteristics of a population from one generation to the next

8. Evolution by Natural Selection
Environment is hostile and has limited resources.
Organisms differ in traits. (Variation)
Some traits give an organism an advantage (sharp claws, eyesight, camouflage) so they can survive and reproduce more than others.
Each generation has proportionally more individuals with the advantageous trait  over generations this can lead to changes in species or new species

9. Nature Selects
Adaptation - process of changing anatomy, physiology, or behavior and improves a population’s ability to survive

10. Nature Selects

11. Coevolution
Coevolution- Process of two species evolving in response to long-term interactions with each other
Example: Hawaiian honeycreeper (bird), has a long, curved beak to reach nectar at the base of a flower
The flower has structures that ensure that the bird will get some pollen on its head so when the bird moves to the next flower, pollen will be transferred

12. Coevolution The honeycreeper’s adaptation is along, curved beak
The plant has two adaptations:
Sweet nectar, which attracts the birds
Flower structure that forces pollen onto the bird’s head

14. Evolution of Resistance
Resistance - ability of an organism to tolerate a chemical or disease-causing agent
An organism may be resistant to a chemical when it contains a gene that allows it to break down a chemical into harmless substances

17. Dogs are One species, why is there so much variation?

18. Why did you pick that one?
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23. Evolution by Artificial Selection
Artificial selection - selective breeding of organisms, by humans, for specific desirable characteristics
Dogs have been bred for certain characteristics
Fruits, grains, and vegetables are also produced by artificial selection---how?

24. REVIEW!!! Explain the process of evolution by natural selection.
Explain the concept of adaptation.
Describe the steps by which a population of insects becomes resistant to pesticide.