1 / 55

EVOLUTION

EVOLUTION. EVIDENCE OF CHANGE. The idea that life has and is changing is not new. Evolution is the process by which modern organisms have descended from ancient organisms. Charles Darwin. Hi, I’m Darwin. Born Feb 12, 1809, died 1882. Grew up in England

tuvya
Download Presentation

EVOLUTION

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. EVOLUTION EVIDENCE OF CHANGE

  2. The idea that life has and is changing is not new. • Evolution is the process by which modern organisms have descended from ancient organisms.

  3. Charles Darwin Hi, I’m Darwin • Born Feb 12, 1809, died 1882. • Grew up in England • Had a strong interest in natural history.

  4. At 22 years old, Darwin was invited to sail on the HMS Beagle.

  5. The Beagle sailed around the world. Whenever the ship anchored, Darwin went ashore to observe and collect animal and plant specimens.

  6. DARWIN’S OBSERVATIONS • Organisms come in a very wide variety of sizes, shapes, and habits. • In one day, he collected 68 kinds of beetles. • There are approximately 10 million species today. • Estimates that 99.9% of all species that have ever lived on Earth are now extinct.

  7. AFTER VOYAGE, DARWIN HAD 2 QUESTIONS… • Where did all the species come from? • Why have so many disappeared? 2 QUESTIONS COME TO MIND…. I wonder if it was a good idea to marry my cousin?

  8. OBSERVATIONS • Darwin noticed that most animals and plants were very well suited to do the things they do. • The combination of physical traits and behaviors that helps an organism survive and reproduce is called FITNESS

  9. HERE’S SOME QUESTIONS: • How did the organisms develop structures that give them their fitness? • Why are there such a variety of techniques for survival?

  10. 1859 • Darwin publishes The Origin of Species by Means of Natural Selection • Proposed that modern organisms have been produced through evolution.

  11. EVOLUTION • A long, slow process of change in a species over time.

  12. HERE’S SOME QUALITY INFO: Now I’m not going to get any credit • Alfred Wallace, a naturalist in the Far East, also came up with the idea of natural selection. He wrote to Darwin about his idea, only to then have Darwin quickly publish the idea first!

  13. TWO IMPORTANT DEFINITIONS: • COMMON DESCENT: species have descended from common ancestors. • ADAPTATION: a process that causes fitness (better able to survive and reproduce).

  14. Adaptations • Long legs and neck of giraffe are adaptations • Long legs and neck allow giraffes to eat leaves too high for other grazing animals.

  15. Age of Earth • Earth is approximately 4.6 Billion years old. • Life has changed dramatically over time. • Common descent has taken place

  16. IN THE PAST, PEOPLE BELIEVED: The Earth is a few thousand years old..tops • The Earth was a few thousand years old • Earth remained unchanged • Humans, rarely, if ever, witnessed the earth changing

  17. BUT THEN SOME INTELLIGENT SCIENTISTS CAME ALONG… Scientists in the 18th and 19th Centuries examined the Earth and suggested that the Earth is 1) very old and 2) changed slowly by forces such as weather.

  18. JAMES HUTTON A non-changing Earth… absurd! • 1788: Proposed that rocks, mountains, and valleys had been changed gradually by rain, heat, cold, and the activity of volcanoes.

  19. While scientists were hypothesizing about Earth’s age: • Geologists began to discover fossils. • Fossils: preserved remains of ancient organisms.

  20. Relative Dating Absolute Dating Two Methods to Date Fossils:

  21. GEOLOGIC TIME SCALE: A CLOCK IN THE ROCKS • Forms a record in the rocks. • Scientists noticed that certain layers appeared in the same vertical order wherever they were found. • It is the position of the layers relative to each other that tells how old rocks and fossils within them are.

  22. RELATIVE DATING • Technique to determine age of fossils by comparing the layers they are found in • The lower layer is the OLDEST. • Cannot tell actual age, just RELATIVE to other layers.

  23. RADIOACTIVE DATING • By the mid 1900s, our understanding of radioactivity gave scientists a tool to determine the actual age of rocks.

  24. Radioactive elements break down, or decay, into non radioactive elements at a constant rate.

  25. ERNEST RUTHERFORD Every element has a HALF-LIFE. This is the length of time required for half of the element to decay. In 1 half life: ½ radioactive element broken down 2 half lives: ¾ broken down 3 half lives: 7/8 broken down.

  26. REMEMBER: • Each element has a different rate of decay, and therefore a different HALF-LIFE! Hmmm….if a fossil has potassium in it, I can figure out how old it is by knowing the half life of potassium!

  27. Potassium 40: Half life is 1.3 Billion years. In one half life of P-40,one half of the atoms decay to argon-40 Uranium 238: Half life of 4.5 Billion years. In one half life, one half of the atoms decay to lead-206. Radioactive Decay:

  28. RADIOACTIVE DECAY CHART

  29. Using radioactive decay, scientists can accurately date fossils. • This is known as ABSOLUTE DATING.

  30. QUALITY QUESTIONS: • What does the X axis (number of shakes) correspond to? • The number of half lives.

  31. THE FOSSIL RECORD • The history of life is recorded by the remains from the past. • Animals and plants can be preserved by natural means

  32. Can be trapped in tree sap-amber

  33. Trapped in sedimentary rock

  34. When a fossil is formed: • Minerals replace the organic components (usually the shell or bone) • Most fossils are found in sedimentary rock

  35. How do fossils form? • Sand, mud and small rocks settle down and COMPACT together, forming layers upon layers.

  36. Unfortunately… • The fossil record is not complete. • Not every organism leaves a fossil. • For every organism that does leave a fossil, many do not leave anything.

  37. Also… • Becoming a fossil depends on where an organism lives. Thank goodness we didn’t live in the mountains where it is hard to become a fossil!

  38. Sometimes Nature Helps: • Weather or water may erode newer layers to expose fossils.

  39. But Remember: • Some fossils are not as well preserved as others. • In some fossils, you can see microscopic detail…in others, not so much!

  40. Paleontologists: I’m a scientist who studies fossils.

  41. My job is to collect a fossil record that represents a preserved collective history of Earth’s organisms.

  42. Horse Fossil Record:

  43. Remember: • Changes in species follow changes on Earth! • As Earth’s conditions changed, species had to either adapt or become extinct!

  44. In case fossil evidence wasn’t enough….

  45. There’s Evidence in Structure!

  46. Homologous Structures • Structures in species that have the same evolutionary origin.

  47. Vestigial Organs • Small or incomplete organs that have no apparent structure. • Tailbone, appendix, ear muscles, pink lump in the corner of your eye….all vestigial organs!

  48. Snakes have some bones that serve no apparent function, but other reptiles with legs ALSO have similar bones. • Hypothesis:…..What do you think???

  49. Amphibian Evolution:

More Related