1. Natural Selection and Evolution

2. Natural Selection
Natural Selection is a phenomenon that’s based off of the phrase, “Survival of the Fittest”.

3. Survival of the Fittest
But what is fitness?
Fitness is the genetic success and contribution of an individual to future generations.
Fit individuals have a lot of viable offspring
Individuals with higher fitness become more common!

4. The evolutionary race Lions eat gazelle.
If the lion gets better at killing gazelle, the lions reproduce, and the gazelle start to die (duh.)
So, the gazelle needs to run faster to avoid getting eaten.
If the gazelle get too fast, the lions can’t catch the gazelle, the lions start to die, and the gazelles live to reproduce.

5. It’s a constant cat and mouse game.
If the lion stops evolving, it dies because it can’t catch the gazelle.
If the gazelle stops evolving, it dies because the lion eats all the gazelle.
To stop evolving means DEATH!!!

6. Basic concepts of natural selection and evolution!
Variation
Inheritance
Selection
Time

7. VARIATION
Variation – individuals in a population vary from one another.

8. INHERITANCE
Inheritance – parents pass on their traits to their children genetically.

9. SELECTION
Selection – individuals with favorable traits reproduce more than individuals with unfavorable traits.

10. TIME
Time – successful individuals accumulate with time.

11. RECAP
Variation
Inheritance
Selection
Time

12. Adaptation
Inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment.
Gills on a fish, wings on a bird, spines on a porcupine, leaves on a venus fly trap.

13. Example of an amazing adaptation to a harsh environment…
In the bogs favored by Venus Flytraps, the soil is acidic, and minerals and other nutrients are scarce.

14. Adaptation leads to diversity
Individuals that adapt best to their environment survive long enough to reproduce.
Genetic variation -> selection for best traits -> offspring that inherit best traits from parents

15. Selection for “best” individuals
Natural selection “selects” for individuals that do best in their environment.
For example, attracts mates (peacock feathers), fights better (horns, spines), defends better (poisonous, noxious), hides better (camouflage), runs faster, etc.

16. Favorable traits let you survive long enough to make babies.
Animals that do the best in their environment survive long enough to reproduce and make offspring that ALSO have favorable traits!

17. Unfavorable traits aren’t good.
Animals with unfavorable traits die off, and don’t get to make babies.

19. So everyone is a predator…
And you eat colored circles.
Find as many circles as you can. The more you find, the more you and your family have to eat.
You have 30 seconds.
Go!

20. The natural selection game

21. Natural selection leads to evolution
In essence, natural selection is nature’s way of “upgrading” organisms.
Upgrades might mean bigger horns, larger feathers, better camouflage, and even better eyes…

22. Evolution of the eye

23. Question for the curious thinker…
If natural selection is based on favorable inherited traits, then why don’t individuals reproduce asexually?
After all, the favored traits would still exist right?
And sexual reproduction is costly!

24. So why have sex?
Why is sexual reproduction better than asexual reproduction?