1. Fossil Evidence

1. 1. Fossil Evidence Prediction: If life has changed over time then we should find evidence of organisms different from those found today. • Fossils are the remains of plants or animals that lived a long time ago or the evidence of them. • Hard parts of the organism are replaced by minerals.

3. RELATIVE DATING Sedimentary Rock is formed in layers - the older beds are on the bottom, and the younger beds are on the top. ALLOWS ONE FOSSIL TO BE COMPARED TO ANOTHER…FOR EXAMPLE—THE SHELL IS OLDER THAN THE HORSE, BUT YOUNGER THAN THE FISH. WE DON’T KNOW THE EXACT AGE, JUST THE RELATIVE AGE YOUNGEST ROCK LAYER OLDEST ROCK LAYER TOP BOTTOM

4. Carbon 14 Nitrogen 14 Half life = 5730 years Radiometric Dating • Radioactive Decay: Naturally-occurring radioactive materials break down into other materials at known rates. • Many radioactive elements can be used as geologic clocks. • Time can be estimated by measuring the amount of radioactive element in a sample. • Half Life = Amount of time it takes for half of the radioactive element to decay Half life = 704 million years Uranium 235 Lead 207

5. = Carbon 14 (radioactive) = Nitrogen 14 (stable)

6. = Carbon 14 (radioactive) = Nitrogen 14 (stable) After an organism dies, the C14 begins to decay into N14

7. = Carbon 14 (radioactive) = Nitrogen 14 (stable) After an organism dies, the C14 begins to decay into N14

8. = Carbon 14 (radioactive) = Nitrogen 14 (stable) After an organism dies, the C14 begins to decay into N14

9. = Carbon 14 (radioactive) = Nitrogen 14 (stable) This decay happens at a constant rate– in 5730 years HALF of the C14 will have decayed into N14

10. = Carbon 14 (radioactive) = Nitrogen 14 (stable) SO, AFTER 1 HALF LIFE—50% REMAINS

11. = Carbon 14 (radioactive) = Nitrogen 14 (stable) THE DECAY CONTINUES--

12. = Carbon 14 (radioactive) = Nitrogen 14 (stable) AFTER A 2ND HALF LIFE-THERE IS 25% REMAINING (50%25%)

13. = Carbon 14 (radioactive) = Nitrogen 14 (stable) AFTER A 3RD HALF LIFE-THERE IS 12.5% REMAINING (25%12.5%)

14. Decay • 100%50% (1 half life) • 50%25% (2 half lives) • 25%12.5% (3 half lives) • 12.5%6.25% (4 half lives) • 6.25%3.125% (5 half lives) Challenge Question: A bone is found to have 25% of its carbon-14 remaining. How old is it estimated to be?

15. 2. Homologous structures Prediction: if organisms shared common ancestors then we should find evidence of similar structures. • Similar anatomical features that originated in a shared ancestor. If time, explore the Zoo of You

16. 3. Vestigial structures Prediction: If new species develop from previously existing species then we should find evidence of features that are no longer used today, but were important in ancestors • Structures that are useless to an organism but are similar to functional structures of related organisms or ancestors

17. 4. Embryology Prediction: If organisms shared common ancestors then we should find evidence that the embryologic structures develop in similar patterns. • The study of the early stages of development of an organism (inside the womb or inside the egg) If time, play Guess the Embryo

18. 5. Comparing DNA and protein sequences Prediction: If organisms shared common ancestors then we should find evidence of similar DNA sequences being used to build similar proteins. The more closely related two species are, the more similar their DNA.

19. 1 9 14 18 Hypothesized relationship based on number of amino acid differences in cytochrome c 21

20. Family Trees (Phylogenetic Trees) • Are based on evidence, such as homologous structures or DNA/proteins • Provide hypotheses about evolutionary relationships: • how long since two species shared a common ancestor (length of line) • How closely related two organisms are (branching from common ancestor)

21. Phylogenetic tree based on number of cytochrome c differences RHESUS MONKEY KANGAROO BULLFROG TURTLE TUNA LAMPREY

22. WHICH 2 ORGANISMS SHOW THE CLOSEST RELATIONSHIP? Human and Monkey- shortest branches 2) WHICH 2 ORGANISMS’ COMMON ANCESTOR LIVED THE LONGEST AGO? Tuna and Lamprey- longest lines

23. 3) WHICH TWO ORGANISMS’ ANCESTOR LIVED MOST RECENTLY? 4) IF YOU DIDN’T KNOW WHAT KIND OF ANIMAL A LAMPREY IS, BASED ON THE TREE-WHAT KIND OF ANIMAL WOULD YOU PREDICT IT IS? Similar to a fish because it has a common ancestor with Tuna

24. 5) COMPARE THE HUMAN-MONKEY RELATIONSHIP WITH THE HUMAN KANGAROO RELATIONSHIP. Human- monkey have more in common because of closer branches. Human- kangaroo have a common ancestor but less related because of longer lines. 6) WHY IS THE KANGAROO IN THE SAME GROUP AS THE HUMAN AND MONKEY-EVEN THOUGH THEY AREN’T AS CLOSELY RELATED? Common ancestor (both are mammals)

25. Green sea turtle Logger head turtle Map turtle American alligator Lace monitor lizard • Which pair of species has the fewest differences in their amino acid sequences for myoglobin (a protein)?

26. Green sea turtle Logger head turtle Map turtle American alligator Lace monitor lizard • How does the relationship between green sea turtles and loggerhead turtles compare to the relationship between alligators and monitor lizards? Turtles closer related because shorter branches Alligator and lizard have common ancestor but less related

27. Sketch a Phylogenetic Tree • A tiger and lion share have 5 differences in their amino acid sequences for the protein Hemoglobin B. They share a common ancestor, which was cat-like. • A hyena and a wolf have 18 differences in their amino acid sequences for Hemoglobin B. They share a common ancestor that was dog-like. • Both cat-like creatures and dog-like creatures share a common ancestor (mammals with paws). Draw a phylogenetic tree that illustrates this data. Be sure you pay attention to the distances that animals are from their common ancestors.