1. EVOLUTION and NATURAL SELECTION

2. Evolution = change over time
Remember the
Earth is estimated
to be _______________
years old!
4.6 Billion

3. Charles Darwin 1831 Sailed to Galapagos Islands
Noticed that species diversity was greater than we thought.
Each plant and animal was adapted to its special environment on the island.

4. Darwin’s Finches
Each island had its own type of finch that was clearly different from finches on other islands
The different beak structures were adapted to the finch’s source of food.

6. Darwin’s Summaries 1. Organisms differ; variation is inherited
2. Organisms produce more offspring than survive
3. Organisms compete for resources
4. Organisms with advantages survive to pass those advantages to their children
5. Species alive today are descended with modifications from common ancestors

7. Environmental stress The dance of survival Natural selection
Darwin’s proposed theory that organisms better suited for an environment are more likely to survive and pass on their traits is called?
Environmental stress
The dance of survival
Natural selection
Founder’s effect

8. Natural Selection results in:
Adaptation – trait that gives advantage
Behavior – action that gives advantage
Extinction – all species die
Speciation – new species forms

9. Adaptation
Inherited characteristic that increases an organism’s chance of survival

10. Mimicry
the similarity in appearance of one species to another that protects one or both.
Example: hoverflies look like stinging wasps

11. Camouflage when a species resembles its surroundings
Flounder with rocks on sea floor
grasshopper

12. Behavior

13. Extinction Speciation Over time the life on Earth changes.
Nature selects individuals in a population that are the most “fit” and those pass on their genes.
If the entire species die it is called ________________.
If a new species forms it is called ______________.
Extinction
Speciation

14. Extinction

16. SPECIATION Is the formation of new species.
Occurs through 4 different mechanisms.

17. ISOLATING MECHANISMS…
BEHAVIORAL ISOLATION-
Capable of breeding but have difference in courtship rituals

18. Bird of Paradise

19. ISOLATING MECHANISMS…
2. GEOGRAPHICAL ISOLATION – separated by geographic barriers.
Rivers
Mountains
Oceans

20. These squirrels live on opposite sides of the Grand Canyon
These squirrels live on opposite sides of the Grand Canyon. This is an example of geographical isolation.

21. ISOLATING MECHANISMS…
3. TEMPORAL ISOLATION –
2 or more species reproduce at different times.
Like Winter and Spring

22. ISOLATING MECHANISMS…
4. REPRODUCTIVE ISOLATION-
when members of 2 populations can no longer interbreed
For example, damselfly penises only “fit” with the correct mate.

23. Speciation causes Biodiversity

24. Artificial Selection The intentional breeding for certain traits.
This chihuahua and great dane show the wide range of dog breed sizes created using artificial selection.

25. Tigon
Result of male tiger and female lion mating incaptivity. Offspring are infertile.
Separated both geographically and ecologically.

26. Liger
Result of male lion and female tiger mating in captivity. Offspring are infertile.