TEACHER NOTES This PowerPoint was revised January 3, 2005.

EVIDENCES OF EVOLUTION Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events

EVOLUTION IS Genetic change in a population through time.

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.

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

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

1 - FOSSIL RECORD Most fossils are found in layered sedimentary rock Oldest fossils are on the lowest layer

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

2 - BIOCHEMICAL THE GENETIC CODE Triplets of DNA nitrogen-base sequences that code for specific amino acids The amino acid triplet is the same in almost all organisms.

2 - BIOCHEMICAL The similarity of triplet DNA codes making-up amino acids shows:  A probable common ancestor for all life on Earth

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

2 - BIOCHEMICAL AMINO ACID SEQUENCING The amino acid sequence in a particular protein is compared between organisms. Number of differences from human hemoglobin

2 - 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.

What organism belongs at each branch? 2 - 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 G F E D C B A Common ancestor Where would the common ancestor be?

3 COMPARATIVE ANATOMY HOMOLOGOUS STRUCTURES structures with similar structure but different function ex: limbs of vertebrates (turtle, alligator, bird, mammal) Turtle Alligator Bird Mammal

3 COMPARATIVE ANATOMY Homologous structures show  Similar genes  Descent from a common ancestor Turtle Alligator Bird Mammal Ancient lobe-finned fish

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

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

3 COMPARATIVE ANATOMY EMBRYOLOGY Embryos of different species may appear similar in early stages of development ex: vertebrate development

3 COMPARATIVE ANATOMY Comparison of similarities in embryos can show:  Relationship to a common ancestor

4 - BIOGEOGRAPHY GEOGRAPHIC DISTRIBUTION OF ORGANISMS organisms living widely apart (even different continents) may be similar because they share a common ancestor Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara  Shows common ancestor

5 - 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

5 - 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

Works Cited “Geographic Distribution of Organisms” photo: Miller, Kenneth and Levine, Joseph. (2004). Biology. Prentice Hall.