Evidence for Evolution (Cont’d)

1.  The Fossil Record2.  Biogeography 3.  Anatomy4.  Embryology 5.  Molecular Biology6. 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 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

Homology: traits inherited by two different organisms from a common ancestorAnalogy: similarity due to convergent evolution, not common ancestry

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• 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?

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

PIG FETUS

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

Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humansNumber of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans

100 20 30 40 50 60 70 80 90 100 110 120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

STSE- A Chickenosaurus ?!

"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."

Hans Larsson, Canada Research Chair in Macro- Evolution at Montreal's McGill University

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

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• Read pg. 296-302

• Pg. 303 #4-7

• Pg. 303 #1 and 2

Consolidation• 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