Natural selection is the mechanism of evolution proposed by Darwin in his 1859 book On the Origin of Species. It describes how traits that aid survival in an organism's environment become more common over generations as those organisms are more likely to reproduce. Variations in heritable traits within a population mean some individuals are better suited to the environment and more likely to survive and pass on their traits, such as grey mice being less visible to predators in a parking lot than white mice.

1. Natural Selection

2. Natural Selection
The title of Darwin's evolutionary biology book in
1859 was:
On the Origin of Species by Means of Natural
Selection, or the Preservation of Favoured Races in
the Struggle for Life

4. Natural Selection
Darwin suggested that Natural Selection is the
mechanism of evolution.

5. Think. Pair. Share.
What is happening in this picture?

6. Natural Selection
Natural selection is the favouring of a trait that is
best suited for survival in its environment.

7. Natural Selection
These traits arise from mutations.
(Is this real?)

8. Natural Selection
Many different traits within a species is called
variation, and these variations are heritable.

9. Natural Selection
Depending on the environment, different traits from
a variety of species are more viable.

10. Natural Selection
For example:
•There is a population of mice living in a parking lot.
Some are white and some are grey.
•When a predator flies over the parking lot, it will eat
the first mouse it sees.

11. Natural Selection
For example:
•Since the grey mice are more difficult to see on the
concrete, white mice will be eaten more often than
grey mice.
•Nature has selected the grey fur allele for survival in
this case.
•The white fur allele may eventually die out in the
parking lot population.

12. Natural Selection

13. Natural Selection
Which of these mantises are most likely to survive?
... In this desert?

14. Natural Selection
Which of these cows are most likely to survive?
... In this prairie?

15. Natural Selection
Which of these butterflies are most likely to survive?
... In this forest?