1. Charles Darwin’s Theory that Shapes the Scientific Study of Life
Natural Selection
Charles Darwin’s Theory that Shapes the Scientific Study of Life

2. Charles Darwin H.M.S. Beagle Sailed around world
Made observations, collected evidence
Formed theory of how life changes

3. Darwin’s Findings Diversity
Amazed by # of different strategies for survival and reproduction
Noticed different plants and animals seemed very well suited for their specific environment

4. Darwin’s Findings Fossils Collected many fossils
How did so many of these species disappear?
How were they related to living things?

5. Some Fossils…

6. Darwin’s Findings The Galapagos Islands
Greatest influence on Darwin’s theory
Let’s examine 2 specific findings there

7. Darwin’s Findings The Galapagos Islands – The Finches
Each type was well suited for its own environment

8. Diversity in Finches

9. Diversity in Finches

10. Darwin’s Findings The Galapagos Islands – The Finches Key Point:
Each different type of beak was optimal for each different finch’s survival needs
Seed eater – large crushing beak
Insect eater – slender grasping beak

11. Darwin’s Findings The Galapagos Islands – The Tortoises
Darwin observed
tortoises on different
islands
He noticed that
tortoises from
different islands had
slight differences in
the shape of their
shells

12. Diversity in Tortoises

13. Darwin’s Findings The Galapagos Islands – The Tortoises Key Point:
Each different type of shell was optimal for each different tortoise’s survival needs
Sparse vegetation – long neck, open shell
Ample vegetation – shorter neck, dome shell

14. Figuring it Out
Darwin noticed how organisms were so well suited for their own specific habitat
Key question: how did they get like that?
Answer: the process of natural selection

15. Publishing his Ideas 1858: On the Origin of Species
In this book, Darwin explained his theory of natural selection

16. Natural Selection “Survival of the fittest”
Those individuals that are best suited for their environment survive and reproduce most successfully

17. Natural Selection Competition
Most fit  survival  reproduce  pass on traits
Less fit  die  no reproduction  bad traits become less common

18. Adaptations Fitness = result of adaptations. Adaptation
Any inherited characteristic that increases an organism’s chance for survival

19. Amazing Adaptations!
Height

20. Amazing Adaptations!
Color/
camouflage

21. Amazing Adaptations!
Camouflage

22. Amazing Adaptations!
Camouflage

23. Amazing Adaptations
Mimicry

24. Amazing Adaptations
Defense

25. Amazing Adaptations
Defense

26. New Observations
Darwin would later make observations that would cause him to question his own theory!
Let’s look at each of these observations…

27. New Observations
The long tailed widowbird

28. New Observations
The peacock

29. New Observations
Only in the males
Connection to mating

30. New Observations
In the long tailed widowbird, the longer the tail, the more likely it was that the individual would mate
In the peacock, the larger the feather spread and the more spots, the more likely it was that the individual would mate

31. Sexual Selection Darwin noticed: Darwin theorized:
Females prefer some characteristics in males over other characteristics
Darwin theorized:
Certain characteristics are selected for NOT as an environmental adaptations, but rather as preferences of females