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How Does Evolution Happen?

How Does Evolution Happen?. Chapter 7 Section 2. Charles Darwin (1809-1882) Sailed around the world 1831-1836. 22 yrs old HMS Beagle Ship’s naturalist Galapogos Islands Discovered: Adaptations Natural Selection Sucessful Reproduction Inherited Variations Competition

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How Does Evolution Happen?

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  1. How Does Evolution Happen? Chapter 7 Section 2

  2. Charles Darwin (1809-1882) Sailed around the world 1831-1836 • 22 yrs old • HMS Beagle • Ship’s naturalist • Galapogos Islands • Discovered: Adaptations • Natural Selection Sucessful Reproduction Inherited Variations Competition Overproduction • Theory of Evolution – What did he not know about??GENETICS

  3. How did tortoises and birds differ among the islands of the Galapagos? • Each island had its own type of tortoises and birds that were clearly different from other islands

  4. Finches on the isolated islands of the Galapagos developed different beaks because of the food they ate. They adapted to the food sources available. F

  5. Natural selection Individuals that are better adapted to survive in an environment are able to live to reproduce and pass on their genetic material. Adaptation and natural selection occur together as organisms change over time.

  6. What factors affect how natural selection works? Overproduction– species produce more offspring than the environment can hold Competition– offspring must compete for resources. Those that succeed, live to pass on genetic information. Inherited Variations– offspring always differ from each other. Sometimes these variations help individuals be more successful. Successful Reproduction– organisms best adapted to their environment are likely to have many offspring that survive. The successful variations accumulate over many generations which causes the species to change over time.

  7. An example of changes in a population over time. http://evolution.berkeley.edu/evolibrary/article//bergstrom_02

  8. An Example of Natural Selection The Peppered Moths of Manchester, England

  9. Peppered Moths of England – Natural Selection Before the industrial revolution in Britain most peppered moths were of the pale variety that were well camouflaged against the pale birch trees that they like to sit on. Moths with the mutant black coloring were easily spotted and eaten by birds - giving the white peppered variety an advantage.

  10. Peppered Moths of England – Natural Selection http://www.bbc.co.uk/schools/gcsebitesize/biology Then the industrial revolution came along in the 19th century. Airborne pollution in industrial areas darkened the birch tree bark with soot, and now the mutant black-peppered moths blended better against the darkened bark, while the white variety became much more vulnerable to predators. Over time the mutated black peppered moths were naturally selected to survive and became far more numerous in urban areas than the pale variety.

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