Evolution (Intro) PDF

1. What is EVOLUTION? Suggest a definition for what you think evolution is. 2. Evolution is the UNIFYING THEORY OF BIOLOGY because it helps us explain and understand the DIVERSITY of life on the planet. In your own words: define diversity: Here is a clue! 3. Big Cat Observation...

1. What is EVOLUTION? Suggest a definition for what you think evolution is. 2. Evolution is the UNIFYING THEORY OF BIOLOGY because it helps us explain and understand the DIVERSITY of life on the planet. In your own words: define diversity: Here is a clue! 3. Big Cat Observations Lions live in Africa Tigers live in India. How are they similar? How are they different? 4. Ligers - a cross between a lion and a tiger How does evolution explain this? Lions and tigers are related! They are similar enough that they can produce offspring. 5. Theories are statements or models that have been tested and confirmed Theories…. 1. Explain data and observations 2. Can be used to make predictions 3. Are not absolute, and can be changed 6. Questions can be answered using established theories. Question: Why do so many different animals have the same bone pattern in their limbs? Answer: They are all related. 7. Predictions can also be made using theories. Do these animals lay eggs? How do you know? They are birds and all birds lay eggs. Photo courtesy of Swamibu, Flickr Creative Commons 8. Main ideas of evolution… - change in frequency of traits in a population over time - organisms came from pre-existing organisms Frequency refers to the number of organisms that have a particular trait. Example. 80% of the mouse population on an island is dark colored. 20% is light. If you had an idea that was going to outrage society, would you keep it to yourself? ~ Charles Darwin 10. Species found at the Galapagos Islands Marine Iguana Blue-footed booby , 9. Charles Darwin developed the Theory of Evolution by NATURAL SELECTION He traveled to the Galapagos islands where he observed animals that were different from the mainland. Giant tortoise Finch This bird had a different variety for each island. The shape of the beak was related to the food it ate. 11. Finches of the Galapagos -Each was adapted to eating a particular type of island food -He concluded that all came from one ancestor Video on Galapagos Finch Evolution by HHMI ~16 min 12. VIDA Key Points to the Theory of Evolution by Natural Selection Variation among individuals. Inheritance - variations are passed from parents to offspring Differential survival and reproduction - more offspring are born than survive Adaptation - the trait that helps individuals survive increases over time 13. The VIDA chart can be used to summarize how a species like the finch evolved. What evidence is there for “differential survival and reproduction” among the finches on Daphne island? Evolution Graphic: Wolves and Rabbits 14. Adaptations - favorable traits that help organisms survive and reproduce What adaptations do snakes have? Sharks? Humans? 15. Natural selection is the process by which evolution occurs. - Nature “selects” winners and losers based on adaptations - over time, the frequency of those traits increases. Who are the “winners” in the comic above? 16. Artificial Selection - humans select variations they found useful and bred animals and plants for those traits. Examples: Dog breeds and other domesticated animals, like pigs and cows 17. Evolution of Pets Dogs evolved from gray wolves Cats evolved from African Wild cats 18. Much of our agriculture (food, animals, clothing) is a result of artificial selection that has occurred over many generations. Gene editing tools might make this process much faster. 19. COMMON DESCENT - Darwin proposed that each living species has descended with modification from other species A phylogenetic tree shows how living species are related and how they descended from a common ancestor. 20. Cladogram - show features common to each group 21. How Do New Species Form? “The Mystery of Mysteries” -Speciation = the formation of a new species -Species = group that can interbreed, and produce fertile offspring. The western and eastern bluebird are different species. Could they create offspring? 22. Mules - hybrids of horses and donkeys Horses and donkeys are separate species. Mules cannot breed together, they are sterile. 23. Evidence of Evolution The theory of evolution is supported by many lines of evidence. - As we gather knowledge, we continue to revise our understanding of the history of life on earth. -Darwin had no knowledge of genetics, but modern biologists can use DNA to establish relationships between organisms HUMAN DNA IS 98% THE SAME AS CHIMPANZEE DNA 24. Fossil Evidence shows….. -similarities between extinct animals and living animals -earth’s layers, and species that lived at each time 25. Fossilized bones can help us reconstruct animals that lived in the past. - they also help us reconstruct a timeline for when these animals lived….and eventually died. 27. Homologous structures – an organ or bone that appears in different animals, having anatomical similarities but may perform different functions. All forelimbs of vertebrates have the same pattern of bones: - one upper bone - two lower bones - digits (fingers) 28. Vestigial Structures – parts that seem to have no function Example: Whales have pelvic bones that do not attach to legs Watch a short video clip on whale evolution at PBS 29. DNA Evidence When comparing the DNA of one species to another, more similarities are found in species that are more closely related. 30. Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks 31. Direct observation of evolution 1. Bacteria become resistant to antibiotics 2. Changes in gene frequencies in populations (rock pocket mouse) 3. Changes in beak size in finches on Daphne Island 32. What happens when populations cannot adapt to a changing environment?