1.  Do you think these two organisms evolved from a common ancestor? ◦ What evidence would you need to convince yourself?

3.  Layers of rock contain fossils ◦ Newer layers of rock cover older ones ◦ Creates a timeline  Fossils can show a record of organisms that lived on Earth over a long period of time

4. Many fossils link early extinct species with species living today Example: Tiktaalik- “missing” link between land and sea animals.

5. A transitional species: Tiktaalik

6.  Like a fish complete with scales and gills  Flattened crocodile head with unusual fins  sturdy interior bones that would have allowed Tiktaalik to prop itself up in shallow water and use its limbs for support as most four-legged animals do.

9. Ancient reptile Thrinaxodon ancient mammal

10. Refers to structural similarities found between related organisms Homologous structures – Limbs that perform different functions but are built from the same bones HumanCatWhaleBat

12.  Species that are only distantly related develop similar adaptations and resemble each other ◦ Because they live in similar environment and are exposed to similar selective pressures On pre-test: 59% got this wrong

13. Analogous structures – structures that resemble each other due to similar selective pressures and not to recent common ancestry

14.  Remains of structures that were functional in ancestors ◦ Eyes on a blind cave fish

16.  Remains of structures that were important to the organisms’ ancestors but are not to the existing organisms  Whale Video ◦ 9:15 On pre-test: 76% got this wrong!

18.  Similarities in DNA and proteins  Amino acid sequences can be compared among various species for minor changes  The more similar the code, the closer related

19. yeast (Candida) 50 40 30 20 10 0 mothfishturtleduckpigmonkeyhuman Types of Organisms Number of Amino Acid Differences Compared to Human Cytochrome c Biochemical/Molecular Data Branch points tell the number of amino acids that differ between human cytochrome c and the organisms depicted

20. Percent Agreement between Beta Globin of Various Species SpeciesHumanChimpGorillaRed foxDog Polar bear HorseRatChicken Human100. 99.391.189.7 83.681.569.2 Chimp100. 99.391.189.7 83.681.569.2 Gorilla99.3 100.91.890.4 82.980.868.5 Red fox91.1 91.8100.98.695.280.880.172.6 Dog89.7 90.498.6100.94.580.179.571.2 Polar bear 89.7 90.495.294.5100.80.882.971.9 Horse83.6 82.980.880.180.8100.76.067.8 Rat81.5 80.880.179.582.976.0100.65.8 Chicken69.2 68.572.671.271.967.865.8100.

22.  Closely related organisms go through similar stages in embryological development  Organisms that appear different as adults may be very similar in embryonic stages = common ancestor

23.  What do you think?  Of these four (in your packet), which do you think is the strongest evidence for evolution?