1 / 14

Evidence for common decent

Evidence for common decent. Case 1 – Vestigial Structures. "Its major importance would appear to be financial support of the surgical profession." Alfred Sherwood Romer and Thomas S. Parsons The Vertebrate Body (1986) , p . 389. Why do we have these? Was it ever useful?.

neith
Download Presentation

Evidence for common decent

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. Evidence for common decent

  2. Case 1 – Vestigial Structures • "Its major importance would appear to be financial support of the surgical profession." Alfred Sherwood Romer and Thomas S. Parsons The Vertebrate Body (1986), p. 389. Why do we have these? • Was it ever useful? The human vermiform appendix (image reproduced with modifications from Gray 1918)

  3. Why do: Whales have hips? Snakes have hind limbs? Humans have an appendix?

  4. Case 2 - Similarities in Body Structure • Homologous Structure = Body structures shared by organisms that were derived from a common ancestor

  5. Case 2 - Similarities in Body Structure Analogous Structure = Body structures with similar function, but not derived from a common ancestor.

  6. Case 3 – Similarities in Early Development The Guessing Game:

  7. Case 4 – Similarities in DNA • Remember that genes control our outward appearance • Genes are made from DNA • Two organisms with a common ancestor should have similar DNA • Scientists determine how closely related organisms are by their DNA!

  8. EXAMPLE: • Who do you think the elephant shrew most related to? We know from DNA tests

  9. Investigation Activity! Group Work (4-5 per group) 1 - Curator (only onewho can touch artifacts) • Take artifacts out of the bags and place on table • Return artifacts BEFORE moving to other tables • Draw and label the structures on a clean piece of paper (detail counts) • Once you have all the drawing complete compare the structures and indicate whether they are homologous, analogous, or neither

  10. Sharks vs Dolphins vs Humans all have fins :

  11. Homologous or Analysis?

  12. Both: but which is which?

  13. Review • You should have: • Evidence for common decent • Vestigial structures • Homologous structures • Similar early development stages • DNA is universal (found everywhere)

  14. Review • You should have: • Evidence for common decent • Vestigial structures • Homologous structures • Similar early development stages • DNA is universal (found everywhere) • Difference between: • Homologous structures • Analogous structures

More Related