1. Why is life on Earth so diverse???
TEST: Friday 10/28

2. Evolution Change over time Descent with modification
Genetic traits passed on to offspring

3. Charles Darwin & The Voyage of the Beagle
In 1831 he traveled around the world on a ship called the Beagle
He noticed that there was great diversity in organisms even in very similar environments
The Galapagos Islands had the biggest impact on Darwin’s studies.

4. Darwin’s Journey

5. What did Darwin See??

6. What did Darwin see?????

7. What did Darwin see?????
Glyptodon (fossil)

8. Evidence of Evolution
Darwin saw many things which influenced his theories……
Fossil Record, the Earth was really old (estimated at 4.5 billion years)
Lamark’s misconceptions on use and disuse of adaptations (crab)
Populations did not grow out of control, there were factors that limited population growth

9. Evidence of Evolution Did you know????
Fossil Records-fossils being discovered were evidence that the world was much older that once thought.
Did you know????
Some fossils were very similar to modern day creatures
99% of species that once lived are now extinct!!!!!!

10. Fossils show history of life on Earth
Relative Dating -The layering of rock can show which fossils are older.

11. Fossils show history of life on Earth
Radioactive Dating -using the half-life of radioactive elements scientists can tell how old a fossil is.

12. Lamark’s Theory
Lamark believed organisms could adapt to fit their environment (ex: fiddler crab)
WRONG
Problem was that he didn’t know about how traits are passed on genetically
His idea that animals are adapted to their environment influenced Darwin’s idea on adaptations

13. POPULATION GROWTH Darwin’s Observations: Darwin’s Inference:
1. organisms produce so many offspring that their population size would increase exponentially if all individuals that are born reproduce successfully. (Green bean analogy)
2. populations tend to remain stable in size, except for seasonal fluctuations.
3. environmental resources are limited.
Darwin’s Inference:
Production of more individuals than the environment can support leads to a struggle for existence, with only a fraction of offspring surviving.
AHA!!!....Darwin said “It is SURVIVAL OF THE FITTEST”

14. Theory of Natural Selection
“ORIGIN OF SPECIES”
In 1859, after 25 years of work, Darwin publishes his work to much ridicule.
Theory of Natural Selection
Darwin proposes that the diversity of life has evolved because the most fit organism in an environment survives and is able to pass on these fitness traits.
Adaptations are characteristics which allow organisms the ability to best survive in their ecosystem.
Pinta Island Intermediate shell
Hood Island
Saddle-backed shell
Isabela Island
Dome-shaped shell

15. Darwin’s Theory is supported by…. ARTIFICIAL SELECTION
Nature provides variation but humans decide what traits are selected and passed on.
Hybridization brings about new variations
donkey
meets
horse....
mule offspring (sterile)

16. Darwin new there was much variation in nature…
Darwin new there was much variation in nature…. Descent with Modification
Darwin proposes that after long periods of time, natural selection results in organisms which are very different from their ancestor.
Different structures
Different niches
Different habitats
COMMON ANCESTOR

17. Reasons for…. Descent with Modifications
Reason for Genetic Variability
Sexual reproduction
Mutations
Migrations
Natural Selection
Genetic Drift

18. Other Evidence for Evolution… Embryology
Embryos tend to look very similar at early stages and cells develop into homologous structures.

19. Embryology

20. Other Evidence for Evolution… Homologous Structures
Traits that are similar in different species because the species share a common ancestor.
Same structure, different function

21. Analagous Structures
Analogous Structures: structures similar in function, but not inherited from a common ancestor. Share similar environments.
Same function, different structure

22. Other Evidence for Evolution… Vestigial Organs
Traces of organs, inherited from ancestors, that seem to have no functional purpose
Hip joint in whales, snakes
Ear muscles in humans
Male nipples
Tailbone

23. Other Evidence for Evolution… Geographic Distribution
Beaver
When similar environments produce similar looking organisms that are unrelated.
Beaver
Muskrat
Beaver and Muskrat
Coypu
Capybara
Coypu and Capybara
Muskrat
Capybara
Coypu

24. Other Evidence for Evolution… Biochemical Evidence
All living things use DNA/RNA as their genetic code
There is very little difference in DNA sequences of most organisms