Evidence of Evolution This PowerPoint was revised Jan 1, 2010 for Unique TEACHER NOTES This PowerPoint was revised June 8, 2004

GENETIC CHANGE IN A POPULATION THROUGH TIME. EVOLUTION IS GENETIC CHANGE IN A POPULATION THROUGH TIME. Population Dynamics POPULATIONS IN ECOSYSTEMS

EVIDENCES OF EVOLUTION Population Dynamics POPULATIONS IN ECOSYSTEMS

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

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 Photos by cbray

FOSSIL RECORD Most fossils are found in layered sedimentary rock Oldest fossils are on the lowest layer Layers diagram by cbray

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

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. Genetic code table by cbray

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

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

Number of differences from human hemoglobin BIOCHEMICAL AMINO ACID SEQUENCING The amino acid sequence in a particular protein is compared between organisms. 8 125 45 27 Amino acid differences designed by cbray (with PPT clip art) 67 1 Number of differences from human hemoglobin

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

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

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

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

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 Whale pelvis diagram by cbray

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

COMPARATIVE ANATOMY Analogous Structures Unrelated species have evolved to have similar adaptations

COMPARATIVE ANATOMY EMBRYOLOGY Embryos of different species may appear similar in early stages of development Embryo drawings by cbray ex: vertebrate development

COMPARATIVE ANATOMY Comparison of similarities in embryos can show: Relationship to a common ancestor Embryo drawings by cbray

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

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

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 Miller, Kenneth and Levine, Joseph. (2004). Biology. Prentice Hall.