Evidence for Evolution (Cont’d) 1.  The Fossil Record 2.  Biogeography  3.  Anatomy 4.  Embryology  5.  Molecular Biology 6. Artificial Selection (last class)   Watch this: http://www.youtube.com/watch?v=faRlFsYmkeY

3. Anatomical Evidence

Homologous Body Structures Helps biologists group animals according to how recently they shared a common ancestor Dolphins look more like fish but their homologies show they are mammals. They have lungs rather than gills and obtain oxygen from air, not water. (evolved from land mammals, not fish)

Homologous Body Structures similar structures inherited from a common ancestor that have different functions in modern species metacarpals humerus ulna radius phalanges Similar structures in different organisms have different functions (you would think similar structures would have similar function) What struck Darwin: what usefulness can finger bones be in a whale flipper; that almost all mammals have precisely 28 skull bones and 7 neck bones regardless of their skull sizes and neck size. So if species had been created in their present forms, why would the skull of a whlae have the same number of bones as the skull of a ouse, and why would the giraffe not be given more neck bones than mammals with the shorter necks Hair is homologous in mammals Similar in number and arrange-ments

Analogous Body Structures Structures of organisms that are not from a common ancestor but perform similar functions These wings are for flying but have different structures

Homology vs. Analogy Something you can relate to. Homology: traits inherited by two different organisms from a common ancestor Analogy: similarity due to convergent evolution, not common ancestry

Pig feet- toes never touch the ground Vestigial organs - remains of a structure that was once functional (e.g. human tailbone) The presence of the organ does not affect its ability to survive and reproduce, so natural selection does not eliminate it demonstrates evidence of change over time Cave fish with no eye Pig feet- toes never touch the ground

Vestigial organs: evolutionary baggage Vestigial structures = evolutionary baggage- features that in an ancestor had served a useful purpose, but had become useless or greatly distorted as the species evolved

Vestigial Structures Examples: wings on flightless birds, human coccyx and appendix The appendix, for instance, is believed to be a remnant of a larger, plant-digesting structure found in our ancestors.

4. Evidence from Embryology All vertebrates embryos develop similarly Similar genes that define their basic body plan We have ‘tails’ as embryos

Which is the human embryo?

PIG FETUS Answer:  All of them except the one above, which is a pig.

5. Evidence from Molecular Biology All organisms use DNA and RNA to transmit genetic information ATP is an energy carrier in all organisms. Similar amino acid sequences in proteins Human and Chimp Karyotype idiogram

BIOCHEMICAL EVIDENCE DNA, Amino Acids, Cytochrome C, hemoglobin are similar in related organisms

Comparative hemoglobin structure Human Macaque Dog Bird Frog Lamprey 8 32 45 67 125 10 20 30 40 50 60 70 80 90 100 110 120 Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans

STSE- A Chickenosaurus ?! Hans Larsson, Canada Research Chair in Macro- Evolution at Montreal's McGill University "If I can demonstrate clearly that the potential for dinosaur anatomical development exists in birds, then it again proves that birds are direct descendants of dinosaurs."

http://www.ted.com/talks/lang/en/jack_horner_building_a_dinosaur_from_a_chicken.html

To ponder: Adaptation? http://www.youtube.com/watch?v=NOjFA4V_Ks4 Or http://www.youtube.com/watch?v=nkI3QsSIGpQ Same story but different treatment for Chris P. Bacon: http://www.youtube.com/watch?v=h6b5_0Bpcu4

Uhm, what evidence would falsify my evolution theory Uhm, what evidence would falsify my evolution theory? Think about it kids.

Btw, if I were still alive, I would be wearing pink today

Homework Consolidation Read pg. 296-302 Pg. 303 #4-7 Pg. 303 #1 and 2 Summarize the various kinds of evidence for evolution (i.e., that all living organisms descended from a common ancestor) Remember: Population evolve; Individuals do not