1 / 22

Change Over Time

Change Over Time. 7 th Grade Science. Evolution – What Science Tells Us. Process by which modern organisms have descended with modification from ancient organisms. Modified due to adaptations – a characteristic that helps an organism survive & reproduce in its environment.

sanjiv
Download Presentation

Change Over Time

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. Change Over Time 7th Grade Science

  2. Evolution – What Science Tells Us • Process by which modern organisms have descended with modification from ancient organisms. • Modified due to adaptations – a characteristic that helps an organism survive & reproduce in its environment. • As populations change over time, new species form.

  3. Evidence for Change Over Time • Fossils & Fossil Record: -fossils found in newer layers tend to be more similar to present-day organisms. -all living species descended from common ancestors.

  4. Fossil Record of the Horse

  5. Evolution of Whales • Whales are like fish………. but unlike fish: they breathe air, give birth to live young & produce milk. -WHALES ARE MAMMALS! -Scientists believe whales evolved from ancient land mammals!

  6. Pakicetus (pak-uh-SEE-tuhs) • Earliest whale ancestor -land-dwelling but went in water -ran on 4 legs -about the size of a wolf

  7. Ambulocetus (am-byoo-loh-SEE-tuhs) • Lived mainly in coastal waters -good swimmer, but also waddled on land -about the size of a dolphin

  8. Dorudon (DOH-roo-don) • Lived in oceans – did not get out of water -propelled itself with massive tail -had tiny hind limbs – couldn’t use for walking or swimming.

  9. Modern Whale • Don’t have hind limbs….but they have tiny hip bones!

  10. Vestigial Structures – more evidence • Inherited remnants or “leftovers” of ancestors. • Usually serve little or no function. -ex: hip bones in whales. -Can you think of any?

  11. Vestigial Structures -Humans: -Tailbones -Wisdom teeth -Appendix -Tonsils -Hind legs on boas -Eye stalks in blind cave bats

  12. Homologous Structures – more evidence -Structures that may have different functions, but are very similar skeletally.

  13. Early Development – more evidence -Many organisms look similar during embryonic stages.

  14. How Does Evolution Happen?

  15. Charles Darwin -Scientists before him saw evidence of evolution. -He was the 1st to explain how it happens. -Served as a naturalist aboard H.M.S. Beagle. -Journeyed to Galapagos Islands.

  16. Galapagos Islands

  17. Darwin’s Observations -Studied many plants & animals…but especially finches. -Noticed they differed from island to island & those all differed from the ones in Ecuador.

  18. Darwin’s Conclusion -Environment & resources differed greatly from island to island. -Finches arrived on different islands & adapted to specific environment. -Different species formed over time.

  19. Darwin’s Theory of Natural Selection -Individuals that are better adapted to their environment survive & reproduce. -Survival of the fittest -“Survival” genes passed to offspring. -Driving mechanism of evolution.

More Related