1 / 34

Descent With Modification: A Darwinian View of Life

Descent With Modification: A Darwinian View of Life . Campbell Chapter 22. What Evolution Is. Descent with modification Change in genetic frequencies over time Change with inheritance. From http://evolution.berkeley.edu/evosite/evo101/IIntro.shtml. What Evolution Isn’t.

venecia
Download Presentation

Descent With Modification: A Darwinian View of Life

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. Descent With Modification: A Darwinian View of Life Campbell Chapter 22

  2. What Evolution Is • Descent with modification • Change in genetic frequencies over time • Change with inheritance From http://evolution.berkeley.edu/evosite/evo101/IIntro.shtml

  3. What Evolution Isn’t • It is not a theory that says humans came from apes!

  4. Historical Context of Evolution People have always wondered about the origin of diverse life forms on Earth.

  5. Aristotle and Scala Naturae • Aristotle believed that there was a Divine Creator at the top of a ladder, and everything else descended from that being. From http://www.ivirgil.it/set/Darwin/creazionismo.htm

  6. Carolus Linnaeus • Created a system of taxonomy that did not show relationships between organisms.

  7. Georges Cuvier • Observed changes in fossil layers of rock • Surmised that layers were different due to catastrophes (floods, ice ages)

  8. Lamarckian View of Evolution

  9. What Lamarck Observed • More modern fossils were found in upper layers of rock • This led to the formation of more modern species

  10. Use and Disuse • Body parts used to get along in the environment get stronger and larger • Those that aren’t used, deteriorate.

  11. Inheritance of Acquired Characteristics • Modifications acquired during an organism’s lifetime could be passed on to their offspring.

  12. Dispelling the myths • Neither of these things were possible because they were missing a very important component…

  13. Darwinian View of Evolution

  14. Darwin backgrounder • Grew up very wealthy, educated • Was a med student, then a divinity student • Served as a naturalist for British government on the HMS Beagle

  15. Where Darwin Went

  16. Development of Theory of Natural Selection • Darwin observed 12 species of finches • Noted differences in beaks and how that correlated to food choice

  17. What Darwin noticed • Organisms on the South American continent looked like those on the Galapagos but didn’t live anywhere else • Was influenced by Lyell (Principia Geologica)

  18. Descent with Modification • Supposed that all organisms were related to an ancient ancestor

  19. Natural Selection After studying specimens he collected, analyzing data and reading an essay by Thomas Malthus, Darwin formulated a theory that explained how different species originated.

  20. Tenet #1 • Variation exists among members of a species.

  21. Tenet #2 • This variation is inherited.

  22. Tenet #3 • There are limited resources in the environment. There is a struggle for survival.

  23. Tenet #4 • Organisms with favorable traits are more fit, thus they leave behind more offspring than those who are less fit.

  24. Tenet #5 • These favorable traits persist in the population and will become more frequent.

  25. Result: • Differential reproductive success leads to change in favorable traits among generations

  26. In sum… • Natural selection occurs as a result of interactions between the environment and the genetic variability demonstrated in living organisms. • It is the result of differential reproductive success.

  27. Artificial Selection • Organisms with certain traits are bred repeatedly until population has only that trait • Dog breeds are another good example

  28. Other Evidence for Evolution • There is other evidence that evolution has occurred: • Anatomical • Molecular • Fossil Record • Biogeography Fossil of Archaeopteryx, ancient bird

  29. Homologous Structures

  30. Vestigial Structures • Structures which are smaller or reduced in size because they are no longer used/needed • Whale pelvis • Vestigial legs on snakes • Human appendix

  31. Embryological Similarities • Presence of post-anal tail, pharyngeal gill slits indicates common ancestry • What else does it indicate?

  32. Molecular homologies • Amino acid sequences among vertebrates have similarities • What else is similar?

  33. Fossil Record • Transitional forms show the change from simpler forms to more complex forms

  34. Biogeography • Geographic distribution of species • Similar species live in the same area

More Related