1. Darwin’s Voyages Chapter 5 Section 1
Natural Selection
Darwin’s Voyages
Chapter 5
Section 1

2. A Darwin Voyage Evolution Charles Darwin; 22
A change over a period of time
Charles Darwin; 22
Voyage on the Beagle
1831
5-year trip around the world
Started in England

3. Living Diversity Diversity Scientists estimate…
The variety of living things on earth
Scientists estimate…
Between 5-50 million living species on earth right now
Quite a guess!!!

4. Fossil Diversity Fossils give us a glimpse into the past Extinction
99.9% of all species that have ever lived are now extinct

5. Adaptations Physical and behavioral traits Enable organisms to survive
Catch food
Withstand conditions
Reproduce

6. Fitness The ability of an individual to survive & reproduce
To successfully pass on its genes to its offspring

7. The Galapagos Islands 1000 kilometers west of S. America
600 miles
Small & short islands
Dry & hot
Larger & taller islands
More lush

8. Darwin’s Finches
1 species of finch evolved into many different “specialized” species

9. Giant Tortoise Shells
Tortoises from different islands had different shells
Ah, hah!!!!
Natural Selection
Survival of the fittest
Evolution!!!

10. Vestigial Organs
Wings on flightless birds
Tailbones on primates

11. Homologous Structures
Develop from similar tissues in the early development stages of the organism

12. Arguments for an Ancient Earth
River Valleys
Carved by glaciers over 100,000’s years
Shells found in high elevation mountains
Plate tectonics!!!

13. Problems with Reproduction
Extinction
Birth Rate < Death Rate
Over Population
Birth Rate > Death Rate
Disease
Famine
War

14. Peppered Moths Before the industrial revolution, England
Trees were light in color from lichen growing on them
After the pollution from Ind. Rev.
Lichen died, leaving just the dark bark

15. Helpful Mutations Increases fitness
more offspring than others in population
Becomes more common in the population

16. Evolution
Any change to the relative frequencies of alleles in the gene pool of a species

17. Species
A group of similar-looking organisms that can breed with one another and produce fertile offspring
Bobcat & Lynx

18. Natural Selection
The struggle for existence selects only the fittest individuals to survive in nature
Generation after generation

19. Struggle for Existence
Only the fastest rabbits will escape the lynx
Only the fastest lynx will catch the rabbits