Intro to Evolution!

The Definition… Evolution: All the changes that have transformed life on earth from its earliest beginnings to the diversity that characterizes it today From the earliest microbes to the enormous diversity of modern organisms, including YOU!

The Timeline…

The Mechanism… Natural selection: the differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in relative frequencies of alleles in the gene pool.

The Result… Evolutionary adaptations: a prevalence of inherited characteristics that enhance organisms’ survival and reproduction in specific environments.

The Discovery… On November 24, 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection He made two points: Today’s organisms descended from ancestral species. Natural selection provided a mechanism for evolutionary change in populations.

The Reaction…

That’s blasphemy!! Old Testament and creationism: species were individually designed (the Creator) and did not evolve Natural theology: studying the adaptations of organisms as evidence that the Creator had designed each species for a purpose. Linnaeus: developed taxonomy, a system for naming species and grouping species into a hierarchy of increasingly complex categories

The Overwhelming Evidence… But “its just a theory”, right? Clarification: Theory in colloquial use is closer to the concept of a “hypothesis” in science. In science, a theory is more comprehensive than a hypothesis: Theory: Explanation of natural phenomenon supported by a large body of scientific evidence obtained from many different investigations and observations.

Evidence for Evolution…

1. Artificial Selection

2. Natural Selection in Action

3. Homologous Structures

4. Vestigial Organs

5. Embryological Homologies

6. Molecular Homologies

7. Biogeography

8. Fossils

Discuss with a partner: Which piece of evidence for evolution do you think is the strongest? Which one is the weakest? Why? Discuss any questions you have about the Ch 21/22 Reading Guide.

The Presentation… Your group will be assigned one of the examples that provide evidence for evolution. Present to the class Explanation of the type of evidence Examples (based on the diagram) How this supports evolution or the theory of natural selection. An AP Exam-Level multiple-choice question for the class. Topics: Artificial Selection Natural Selection in Action Homologous Structures Vestigial Structures Embryological Homologies Molecular Homologies Biogeography Fossils

Evidence for dinosaurs evolving into birds Example Presentation Evidence for dinosaurs evolving into birds Birds are decedents of an ancestral species of dinosaurs Birds evolved from therapod dinosaurs during the Jurassic Period (200-145 mya)

Evidence for dinosaurs evolving into birds Example Presentation Evidence for dinosaurs evolving into birds Archaeopteryx is the “missing link” between dinosaurs and aves (birds)

Evidence for dinosaurs evolving into birds Example Presentation Evidence for dinosaurs evolving into birds Hollow bones, feathers, pelvis, sternum, feet, teeth

Example Presentation Which of the following statements about the evolution of birds is false? After the extinction of all dinosaur species in the Jurassic Period, primitive birds began to evolve. The shape of the pelvis, sternum, and feet are evidence that the therapod dinosaurs evolved into Archeopteryx, and eventually into modern day birds. Feathers on the Archeopteryx fossils are evidence that these animals were warm-blooded and could possibly fly, like birds. The Archeopteryx is the ancestral species that descended into all of the avian species.

The Presentation… Your group will be assigned one of the examples that provide evidence for evolution. Present to the class Explanation of the type of evidence Examples (based on the diagram) How this supports evolution or the theory of natural selection. An AP Exam-Level multiple-choice question for the class. Topics: Artificial Selection Natural Selection in Action Homologous Structures Vestigial Structures Embryological Homologies Molecular Homologies Biogeography Fossils

Leadership Reminders: Pasta Feed is this Saturday Each class must bake 5 items for the pasta feed Community Service Opportunity this Wed Creek (Hours are due on March 29, end of Q3) In a group of 4-5, discuss the following: (TURN IN 1 PAPER) What went well in PLANNING the dance? What went well at the ACTUAL dance? What could we do to improve for the next dance? Who do we want to thank? Plan who will share with the class.