1. EVOLUTION
Chapter 16

2. What is evolution?
The process of change over time

3. Charles darwin Born in England
February 12th, 1809 (same day as Abraham Lincoln!)
Developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent of common ancestors

4. HMS Beagle 1831 Five year voyage
Darwin planned to collect specimens of plants and animals

5. Observations aboard the beagle
Species varied globally
Species varied locally
Species vary over time
Observations aboard the beagle

6. What was Charles Darwin’s contribution to science?
Key questions
What was Charles Darwin’s contribution to science?
What three patterns of biodiversity did Darwin note?

7. Found flightless, ground-dwelling birds
Species vary globally
Found flightless, ground-dwelling birds
Rheas- South America
Ostriches- Africa
Emu- Australia
Darwin noticed that different, yet similar, animals inhabited different, ecologically similar, habitats around the globe

8. Species vary locally
Different, yet related, animal species occupied different habitats within a local area
Galapagos Islands
Close to one another but have very different ecological conditions
Tortoises’ shells varied in predictable ways from one island to the other
Hood Island Tortoise
Shells are curved and open, long neck and legs
Isabella Island Tortoise
Dome-shaped shells, short necks

9. “ This wonderful relationship in the same continent between the dead and the living, will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts.”
– Charles Darwin
Species vary over time
Some fossils of extinct animals were similar to living species

10. Darwin found fossils of many organisms that did not resemble any living species. How might this finding have affected his understanding of life’s diversity?

11. 16.2– Ideas that changed Darwin’s thinking

12. An ancient, changing earth
James Hutton and Charles Lyell
Geologists in Darwin’s time
Concluded that Earth is extremely old and that the processes that changes Earth in the past are the same processes that operate in the present

13. Hutton and geological change
Realized the connection between a number of geological processes and geological features
Proposed that forces beneath Earth’s surface can push rock layers upward
Mountain ranges
Deep Time- the idea that our planet’s history stretched back over a period of time so long that it’s difficult for the human mind to imagine

14. Population growth Thomas Malthus Darwin connected Malthus’s ideas
overcrowding of human population
War, famine, and disease
Darwin connected Malthus’s ideas
Why don’t other species survive for several generations?

15. Population growth cont.
Why was this realization important?
Darwin was convinced that species evolved
Needed a scientific explanation to explain how and why evolution occurred
…Which organisms survive, and why?

16. 16.3 – Darwin presents his case
16.3 – Darwin presents his case

17. The struggle for existence
Darwin realized that if more individuals are produced than can survive, members of a population must compete to obtain food, living space, and other limited necessities
The struggle for existence

18. Variation
Individuals have natural variations among their heritable traits
Some variants suited life better than others
Predators with longer claws, sharp teeth, and quick= more prey
Camouflage for prey species = avoid being caught

19. adaptation Adaptation
Any heritable characteristic that increases an organisms ability to survive and reproduce in its environment
Can involve body parts or structures, colors, or physiological functions

20. The scarlet king snake is exhibiting mimicry– an adaptation in which an organism copies, or mimics, a more dangerous organism. Although the scarlet king snake is harmless, it looks like the poisonous eastern coral snake, so predators avoid it too.

21. scorpion fish
A scorpionfish’s coloring is an example of camouflage– an adaptation that allows an organism to blend into its background and avoid predation.

22. Adaptations of behavior
Adaptations often involve many systems and even behavior. Here, a crane is displaying a defensive behavior in an effort to scare off the nearby fox.

23. Survival of the fittest
Fitness
How well an organism can survive and reproduce in its environment
High fitness
Individuals with adaptations that are well suited to their environment can survive and reproduce
Low fitness
Individuals with characteristics that are not well suited to their environment either die without reproducing or leave few offspring