Name ______Date ______Class ______
Chapter 15.1: Darwin’s Theory of Natural Selection (p.418-422)
Daily Objectives- Explain Charles Darwin’s contribution to science.
- Explain how modern organisms have evolved over long periods of time.
Charles Darwin - Developed a theory of evolution based on natural selection.
- Organisms change over long periods of time by natural selection.
- Collected a lot of evidence to support his ideas (rocks, fossils, plants, and animals).
- Lived from 1809 -- 1882
- British naturalist
Darwin’s Journey- Invited to travel around the world on the HMS Beagle
- Boarded the HMA Beagle in 1831.
- Makes many observations of nature
- Main mission of the Beagle was to chart South American coastline.
- The Beagle stopped in the Galapagos Islands.
- Located 500 miles off coast of South America.
Galapagos Islands- Recently formed volcanic islands.
- Most of animals on the Galápagos live nowhere else in the world, but they look like species living on South American mainland.
Unique Species
- Darwin asked: Why were these creatures found only on the Galapagos Islands?
- Darwin Found: Evidence that organisms have changed over time.
ex. Extinct armadillos and modern armadillos can be found on the same continent.
- Fossils are the preserved remains or traces of ancient organism.
Tortoises- Several islands in the Galapagos were home to distinct forms of giant land tortoises.
- The tortoises’ shells varied in predictable ways from one island to another.
- The shape of the tortoises’ shell corresponds to different habitats.
Finches- Darwin found many different birds on the Galapagos Islands.
- He thought that he had found many different types of birds.
- Darwin was amazed to find out:
- All 14 species of birds were actually finches.
- But there is only one species of finch on the mainland of South America.
Darwin Asked:If the Galapagos finches came from the mainland, why are they so different now?
Why do you think the finches evolved into 14 different species? ______
______
______
Darwin’s- Darwin began to hypothesize that new species could appear gradually through small Conclusions changes in ancestral species.
- He called this artificial selection, which we now call selective breeding.
- Different beaks are inherited variations.
- Serve as adaptations that help birds compete for food.
- These birds survive & reproduce more.
- Pass on the genes for those more fit beaks.
Four Principles 1. Individuals in a population show differences, or variations.
Of Natural 2. Variations can be inherited.
Selection 3. Organisms have more offspring than can survive on available resources.
4. Variations that increase reproductive success will be more common in the next generation.
The Origins of - Darwin eventually published On the Origin of Species by Means of Natural Selection.
Species - He used the term evolution on the last page, now biologists use this term to define cumulative changes in groups of organisms through time.