1. EVOLUTION
Chapter 15

2. Evolution - change over time
Theory – a well-supported testable explanation of phenomena in the natural world

3. Charles Darwin

4. The variety of living things…
BIOLOGICAL DIVERSITY
Darwin found a huge variety of living things, each well adapted to their environment

5. Voyage of the Beagle 1831

7. Patterns of Diversity
Visited Argentina and Australia-similar grassland ecosystems
those grasslands were inhabited by very different animals.

8. Patterns of Diversity
Darwin asked questions…
Why no rabbits in Australia, despite the presence of habitats that seemed perfect for them?
Why no kangaroos in England?

9. Living Organisms and Fossils
Darwin collected the preserved remains of ancient organisms, fossils.
Some of the fossils resembled organisms that were still alive today.

10. Living Organisms and Fossils
  Others looked completely unlike any creature he had ever seen.
As Darwin studied fossils, new questions arose.
Why had so many of these species disappeared?
How were they related to living species?

14. The Galapagos Islands
The smallest, lowest islands were hot, dry, and nearly barren-Hood Island-sparse vegetation
The higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation.

15. The Galapagos Islands
The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.

17. More Galapagos Animals

18. The Journey Home
Darwin Observed that characteristics of many plants and animals vary greatly among the islands
Hypothesis: Separate species may have arose from an original ancestor

19. Ideas that shaped Darwin’s Thinking
James Hutton:
1795 Theory of Geological change
Forces change earth’s surface
Changes are slow
Earth much older than thousands of years

20. Ideas that Shaped Darwin’s Thinking
Charles Lyell
Geographical features can be built up/torn down
Darwin thought if earth changed over time, what about life?

21. Lamarck’s Theory of Evolution
Tendency toward Perfection
(Giraffe necks)
Use and Disuse
Theory of Acquired Traits (characteristics)

24. Population Growth Thomas Malthus- English economist
If population grew…
Insufficient living space
Food runs out
Darwin applied theory to animals and plants

25. Publication of On the Origin of Species
1859 after 25 years of study, thought, struggle
It outlined his theories of natural selection and evolution over time

26. His Studies of Variation
Darwin didn’t know about genes
He DID observe traits being passed to offspring
He knew about Artificial Selection – nature provides variation, humans select variations they find useful
Dogs, pigeons, crops, horses, cows

27. Natural Selection
There is a struggle for existence…living things need food, living space
Some individuals are better adapted for their environment
Adaptation – any inherited characteristic that increases an organism’s chance of survival
SURVIVAL OF THE FITTEST

28. Can you think of any adaptations?
Check out these examples of adaptations

29. Descent with Modification
Darwin proposed that living things changed over long periods of time because of natural selection
It implies that all living organisms are related
Living things evolved from a common ancestor
Common Descent
Tree of Life links all living things

30. Evidence of Evolution
Fossil Record
Geographic Distribution of living things
Homologous structures
Vestigial organs
Similarities in embryology

31. Geographic Distribution of Living Things
Darwin found different species of animals on different continents
He recalled similar environments and sometimes similarities in different animals

32. Homologous Structures have different mature forms but develop from same embryonic tissues
Vestigial organs are traces of homologous organs
Ex. Legs in skinks
(p. 385)

33. Similarities in Embryology
Similar in early stages…common ancestry?