1. In your own words, how would you define Evolution? Can you think of an example of Evolution? How do you know when something has evolved?

2. EVOLUTION IS GENETIC CHANGE IN A POPULATION THROUGH TIME.

3. EVIDENCES OF EVOLUTION

4. Charles Darwin On his journey around the world, Darwin found evidence of gradual change (evolution). Darwin cited evidences he found in fossil records, geographic distribution and homologous structures.

5. Evidences of Evolution Today most evidences for evolution are grouped into five main categories: Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events

6. FOSSIL RECORD Paleontology Fossil – remains or traces of an organism that lived long ago Remains: ex. bone, tooth, or shell Traces: ex. burrow, footprint, or imprint

7. FOSSIL RECORD Most fossils are found in layered sedimentary rock Oldest fossils are in the lowest layers Newest fossils are in the top layers

8. FOSSIL RECORD Comparing fossils from different layers shows:  Life on Earth has changed  Increased number of life forms

9. BIOCHEMICAL DNA & the genetic code One codon codes for one amino acid – it works the same way in all species The codon code for each amino acid is the same in almost all organisms.

10. BIOCHEMICAL The similarity of the way DNA codes for amino acids shows:  A probable common ancestor for all life on Earth

11. BIOCHEMICAL “Universal” GENETIC CODE  Similar genes  Over the ages, the genetic code has passed unchanged (or nearly so) from parent to offspring.

12. BIOCHEMICAL AMINO ACID SEQUENCING The amino acid sequence in a particular protein is compared between organisms. Number of differences from human hemoglobin 45167 8 27 125

13. BIOCHEMICAL Comparing amino acid sequence shows:  Closeness of relationship  A probable common ancestor SpeciesDifference Gorilla 1 Rhesus Monkey 8 Mouse 27 Chicken 45 Frog 67 Lamprey 125 Amino Acid Difference in Hemoglobin Compared with Human Human hemoglobin has 146 amino acids Amino Acid Sequencing is probably the STRONGEST evidence for relationships among organisms.

14. What organism belongs at each branch? BIOCHEMICAL CLADOGRAM: diagram that shows the evolutionary relationship among a group of organisms. SpeciesDifference Gorilla 1 Monkey 8 Mouse 27 Chicken 45 Frog 67 Lamprey 125 Amino Acid Difference in Hemoglobin Compared with Human Number of Amino Acid Differences 150 100 50 0 40 20 30 10 G F E D C B A Common ancestor Where would the common ancestor be?

15. COMPARATIVE ANATOMY HOMOLOGOUS STRUCTURES structures with similar structure but different function Turtle Alligator Bird Mammal

16. COMPARATIVE ANATOMY Homologous structures show  Similar genes – similar proteins  Descent from a common ancestor Turtle Alligator Bird Mammal Ancient lobe-finned fish

17. COMPARATIVE ANATOMY VESTIGIAL STRUCTURES organs so reduced in size that they are nonfunctioning remnants of similar organs in other species ex: human tailbone, appendix, gallbladder, whale pelvis

18. COMPARATIVE ANATOMY Vestigial structures show:  an organism’s evolutionary past  a common ancestor with species that have similar structures that are still functioning

20. BIOGEOGRAPHY GEOGRAPHIC DISTRIBUTION OF ORGANISMS organisms living far apart may be similar because they share a common ancestor

22. OBSERVABLE EVENTS Some changes in species have been observed and studied: Peter & Rosemary Grant’s Study of Beak Size Shift in Darwin’s Finches H. Kettlewell’s Study of Peppered Moth Color Shifts

23. OBSERVABLE EVENTS  Observable events show that evolution is an ongoing process Peter & Rosemary Grant’s Study of Beak Size Shift in Darwin’s Finches H. Kettlewell’s Study of Peppered Moth Color Shifts