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?

13. The Galapagos Islands
Islands close together but had very different climates

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

15. More Galapagos Animals

16. 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

17. Darwin’s Tree of Life

18. 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

19. Evidence for Hutton and Lyell

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

22. 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

23. 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

24. 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

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

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

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

30. Descent w/ Modification (cont.)
Common Descent – all species, both alive and extinct, came from common ancestors.
Tree of Life links all living things

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

32. Darwin saw fossils as a record of the history of life on Earth.
Fossil Record
Darwin saw fossils as a record of the history of life on Earth.
He proposed that Earth was many millions of years old.

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

34. Geographic Distribution

35. 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)

36. Similarities in Embryology
-Similar in early stages…common ancestry?
-Embryonic cells develop in same order and pattern
-Common cells produce homologous structures