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Cells & Heredity Chapter 5 Section 1. Darwin’s Theory. I. Charles Darwin. Naturalist – a person who studies the natural world 1. Observed plants & animals 2. Questioned differences. B. HMS Beagle 1. Five year voyage. C. Developed theory of evolution by natural selection.
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Cells & HeredityChapter 5 Section 1 Darwin’s Theory
I. Charles Darwin • Naturalist – a person who studies the natural world 1. Observed plants & animals 2. Questioned differences
B. HMS Beagle1. Five year voyage C. Developed theory of evolution by natural selection
- Darwin’s Theory Darwin’s Voyage • Charles Darwin sailed on the Beagle, from England to the Galápagos Islands. Pages 138 - 139
II. Darwin’s observations • Diversity 1. More than 1.7 million species on Earth a. Can mate & produce fertile offspring B. Fossils 1. Preserved remains or traces of organisms 2. Noticed changes from past to present
III. Galápagos Organisms • Compared to S. American organisms 1. Many similar 2. Iguanas a. Islands – large claws to grip slippery rock b. Mainland – small claws to climb trees
3. Hypothesis • Came from mainland • Reproduced and changed
C. Adaptations – traits that help in survival & reproduction • Finch beaks size and shape a. Help in obtaining food
2. Poisonous plants a. Avoid being eaten 3.Brightly colored flowers or body parts a. Aids in reproduction
IV. Evolution – gradual change in a species over time • Darwin’s reasoning 1. Adaptation to new conditions 2. Similar to selective breeding
V. Natural Selection • The Origin of Species
B. Well adapted individuals survive and reproduce • Overproduction • Variations • Competition
- Darwin’s Theory Overproduction and Variation • Natural selection is the process by which individuals who are better adapted to their environment are more likely to survive and reproduce than other members of the same species. Page 143
4. Selection • Leads to change overtime • Helpful variations accumulate • Unfavorable traits disappear
- Darwin’s Theory Competition and Selection • Variations among turtles make some of them better able to survive. Turtles that survive to become adults will be able to reproduce. Page 144 - 145