1. A Big Idea! (new handout is page 27 ½)
Natural Selection
A Big Idea!
(new handout is page 27 ½)

2. Resources:
stuff that is in the environment that is needed for survival
often limited (can be used up)

3. environment
air
food
organism
mate
shelter

4. Competition:
The effort of 2 or more organisms acting independently to get resources that are in short supply.

5. Variation: Differences in shape, structure, or function
Dangling earlobe
Attached earlobe
Differences in shape, structure, or function
Caused by sexual reproduction or mutation

6. Adaptation:
camouflage
A useful trait that helps an organism to survive, and which gives it an advantage in its environment.

7. Overpopulation:
Too many organisms in one environment
Can lead to competition

8. Overpopulation can lead to competition.1
Overpopulation can lead to competition.

9. Due to competition, some organisms (with useful traits) will live on…2
Due to competition, some organisms (with useful traits) will live on…
...but others will die.
Also called “survival of the fittest”

10. The usefulness of a trait depends on the resources and environment.
brighter stripes
(+) attracting a mate?
(-) more visible to predators?
skinny body
(+) hide or live in small holes?
(-) not so strong for defense?
Speedy swimmer
(+) fast escapes
(-) needs lots of energy (food!)

11. They pass the traits on to their offspring.3
Organisms that have useful traits (adaptations) will survive and then reproduce.
They pass the traits on to their offspring.

13. The environment now has a lot more organisms that have certain traits.4
END RESULT:
The environment now has a lot more organisms that have certain traits.
This is NATURAL SELECTION. (Nature chooses the traits that will increase in the population.

14. HOMEWORK
Page 31 – read and answer questions
(Theory of Evolution)