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

Types of evidence of evolution Fossils Homologies Anatomical Molecular Developmental Biogeography Observable Events

Fossil Record Helps scientists understand pathway of evolution Paleontology Fossil 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 in the lowest layer Newest fossils are in the top layer

Fossil Record Comparing fossils from different layers shows: Life on Earth has changes Increased number of life forms

Reduction of toes over time Fossil evidence Reduction of toes over time

Anatomical Homologies Homologous Structures: Similar structure but different function Shows: Similar genes Common ancestor Turtle Alligator Bird Mammal

Anatomical Homologies Vestigial Structure: Body part reduced in function in a living organism but may have been used in an ancestor Shows: Organisms evolutionary past Whale pelvis & tailbone humans

Developmental Homologies Shows: Similar genes Common ancestor

Developmental Homologies Fish, reptiles, birds, & mammals (yes, even us!) all have a tail, limb buds & pharyngeal pouches in the early stages of development

Molecular Homologies DNA & the genetic code DNA codes for amino acids proteins “Universal” Genetic code The similarity in DNA shows: A probable common ancestor for all life on Earth Genetic code table by cbray

Number of differences from human hemoglobin Molecular Homologies 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 Molecular Homologies 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

Molecular Homologies Amino Acid Difference in Hemoglobin Compared with Human 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 What organism belongs at each branch? Where would the common ancestor be? E F Amino acid differences chart by lpriddy G Common ancestor

Biogeography Geographic distribution organisms living far apart may be similar because they share a common ancestor

Observable Events Some changes in species have been observed and studied Shows: 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

Tempo of Evolution