1 / 28

Chapter 7 Sections 2 and 3

Chapter 7 Sections 2 and 3. Section 2 How Does Evolution Occur?. In the early 1800’s scientists figured out that the Earth is older than previously thought Bizarre fossils were found Fossils were found in odd places Seashell fossils found on mountains. Took the Beagle voyage in 1831

cristalc
Download Presentation

Chapter 7 Sections 2 and 3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 7 Sections 2 and 3

  2. Section 2 How Does Evolution Occur? • In the early 1800’s scientists figured out that the Earth is older than previously thought • Bizarre fossils were found • Fossils were found in odd places • Seashell fossils found on mountains

  3. Took the Beagle voyage in 1831 Had a degree in theology Dad wanted him to be a doctor but he couldn’t watch surgery, it made him sick Charles Darwin

  4. Charles Darwin • Darwin was really interested in studying plants and animals • On his 5 year Beagle voyage, he served as a naturalist, a scientist that studies nature • He took samples and notes about the plants and animals he saw on the trip

  5. Natural Selection • Darwin’s observations became the foundation for evolution by the mechanism of natural selection • Natural selection is also known as survival of the fittest • Individuals with favorable traits will survive and pass those traits into the next generation

  6. Beagle Voyage • Darwin’s trip traveled to the Galapagos Islands, formed by volcanoes, off the coast of Ecuador in South America • Darwin noticed that finches on the islands were similar but different than the birds on the mainland and other islands

  7. Beagle Voyage

  8. Darwin noticed the finches on the islands had different beak shapes and ate different foods Darwin’s Finches

  9. Finches • Darwin thought the finches on the islands originated from finches on the mainland • Darwin figured the wind from a storm helped the birds fly to the new islands

  10. Return to England • Darwin used three sources to develop his evolution theory • Farmers and breeders • Geologists like Charles Lyell • Thomas Malthus

  11. Farmers and Breeders • Selective breeding- traits are chosen that are favorable and only individuals with those traits are bred • Example: Dogs • There are over 150 breeds selective bred from the ancestral canine

  12. In the wild • For these types of changes to happen in the wild, it takes longer • Variations in species is due to chance

  13. Charles Lyell • Darwin learned from Lyell that the earth was formed by natural processes over a long period of time • Due to fossils and current species, Darwin had already thought changes in populations took a long time as well

  14. Charles Lyell

  15. Thomas Malthus • Darwin learned humans and other animals can produce more offspring than the food supply will support • Starvation and disease will kill off the weak and the strong will survive to reproduce the next generation

  16. Thomas Malthus

  17. Increase versus Food Availability Increase in human population Quantity Increase in food supply Time

  18. Natural Selction • In 1858, Darwin started to collaborate with Alfred Russel Wallace • In 1859, Darwin published his research, The Origin of Species by Means of Natural Selection • Darwin believed natural selection is how evolution occurs

  19. Alfred Russel Wallace

  20. Natural Selection • Overproduction • Species produce more offspring than will survive to maturity • Genetic Variation • Individuals are different from each other slightly • Some traits will increase chance of survival and reproductive success while other traits will decrease chances

  21. Natural Selection • Struggle to Survive • Resources will vary in availability (food and water) • Some will be killed while others survive • Successful Reproduction • Well adapted individuals will reproduce and produce offspring with similar “strong” traits while the weak will not live long enough to reproduce or only produce a few offspring

  22. More Evidence • 1930-40’s biologists combine genetic inheritance and Darwin’s theories to explain variance in population • Variations are caused by mutations • Mutation- change in genes

  23. Section 3 • Natural selection explains how a population changes over TIME. • Generation time is the period between the birth of a generation and the birth of the next generation

  24. Insect Resistance • Some insects survive the farmer’s insecticides or poison and survive to produce offspring with the same genes until most of the population is adapted to resist the insecticide

  25. Peppered Moths • Peppered moths have 2 color variations, light and dark • Before the industrial revolution the light moths blended into the trees better and were eaten less by birds and were more abundant in the population • After the revolution, pollution made the trees darker and the darker moths were eaten less and more abundant

  26. Peppered Moths

  27. Formation of New Species • Separation • Part of the population gets separated • Mountains, canyon, roads, river • Adaptation • Environment changes in one area • Individuals adapt to that change • Division • Populations become so different over time they can no longer interbreed and become different species

More Related