Homework: Answer reading questions in HP 13 Are birds more closely related to reptiles or mammals? Explain your reasoning. Homework: Answer reading questions in HP 13

How do we know? http://www.youtube.com/watch?v=j5KjCn7B6mU reptiles! Pose the question "How do we know?" to evaluate students' prior knowledge to the topic. How do we know?

Making Predictions In your notes, you are going to work with your group to make predictions about pictures I show you. Write a 2-3 sentence summary to explain the pictures. Use EVIDENCE in the pictures to form your response Think like a scientists!

Predict why these animals have such similar structures.

Predict why the embryos for these different species would look so similar

Predict why a whale would have a pelvic bone and hip joint but no legs

Summarize your conclusions from analyzing these pictures.

Evolution Defined…. Evolution is defined as GENETIC change over time Example: In 1980 95% of beetles possessed a gene for dark wing color. In 1981 75% of beetles possessed a gene for dark wing color EVOLUTION has occurred!

Where’s the proof? Fossil Records Homologous structures Molecular biology

Evidence for Evolution in the Fossil Record

What is a fossil? How do they form? This slide shows multiple generations of organisms becoming fossils, but also provides an essential concept that the movement of the Earth explains why we find water-based organisms in areas that are now dry and vice verse. Use this slide to explain how the movement of the Earth affects fossil formation and where we find them. Also initiate the explanation of the transition from living organism to fossil. A fossil forms when a dead organisms is buried in sediment

How do fossils give us evidence of evolution? Fossils show the existence of many different organisms that are now extinct AND they show up that organisms that lived a long time ago have similar structures to organisms today

What is a homologous structure What is a homologous structure? A structure that show a similar structure but has a different function Common physical structures, like bones, indicate either common ancestors or similar responses to evolutionary challenges. Descendants of a common ancestor (the common ancestor is believed to be the first organism (tetrapod) that crawled out of the sea onto land. Ask students what these limbs resemble and connect it back to slide 12 and Tiktaalik. Ask students how these limbs have changed to be what they are now. Ask students to describe the process of how a specific limb changed. For example, you could ask them if they have a cat and to describe things the cat does. Maybe they are familiar with it catching other animals (mice, birds, etc.) and you can talk about how the limb changed because changes slowly added up in a way that was most advantageous for the species.

Teacher Instructions: Emphasize the real world example of bird evolution from dinosaurs.

How do homologous structures give us evidence for evolution? They provide evidence that these animals share a common ancestor because of the similarities seen in their structures.

Genetic Similarities Between Species Explain to students that this is a picture of the similarities of nucleotide pairs (x axis) from different species. They are all compared to the human sequence (which would be completely green, because it would match 100 percent. -Emphasize that many of the same genes exist between these organisms. Another human? 100% - All humans have the same genes, but some of these genes contain sequence differences that make each person unique. A chimpanzee? 98% - Chimpanzees are the closest living species to humans. A mouse? 92% - All mammals are quite similar genetically. A fruit fly? 44% - Studies of fruit flies have shown how shared genes govern the growth and structure of both insects and mammals. Yeast? 26% - Yeasts are single-celled organisms, but they have many housekeeping genes that are the same as the genes in humans, such as those that enable energy to be derived from the breakdown of sugars. A weed (thale cress)? 18% - Plants have many metabolic differences from humans. For example, they use sunlight to convert carbon dioxide gas to sugars. But they also have similarities in their housekeeping genes.

Molecular Evidence We can collect quantitative data that proves relatedness between all living organisms today We can use DNA sequences, amino acid sequences, and even protein structure to show molecular similarities to all living organisms