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Evolution

Evolution. The unifying theme of biology. Bellringer. Make these 3 columns and jot down a few ideas. The Ins and Outs. Evolution does argue…. Evolution does not argue…. That all species are related and came from one ancestral species

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Evolution

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  1. Evolution The unifying theme of biology

  2. Bellringer Make these 3 columns and jot down a few ideas

  3. The Ins and Outs Evolution does argue… Evolution does not argue… • That all species are related and came from one ancestral species • That species change over millions of years and can become new species or split into separate species • That the earth is much older than biblical accounts • That there is no God or creator • That we evolved from monkeys or that monkeys should each evolve into humans • That animals should give birth to brand new species overnight

  4. Evolution Does not Address • How life began • Morality • Whether species are “better” or “higher order” • The meaning of life or significance of “being human”

  5. There is very little scientific debate • Scientists debate the details of evolution but there is overwhelming consensus that evolution does occur • There is a lot ofevidence

  6. But evolution is a theory… • A “theory” in science is a well-supported argument that matches all experimental evidence and is widely accepted – like gravity • Scientists never say we “prove” or we “know”. We say “the data suggests or supports”

  7. The First Person to Suggest Evolution was… • NOT Charles Darwin, but • Jean Baptiste Lamarck revived a theory that existed for thousands of years • Suggested species change over time and can become new species • BUT he had no evidence, and his hypothesis did not properly explain how evolution could occur

  8. Charles Darwin • Proposed a well-thought out, coherent, well-researched hypothesis • Was scared to publish for many years- in fact a man named Alfred Wallace published at the same time • But Darwin’s version was more complete so he gets all the credit

  9. 2 Main Parts to the Theory Descent with Modification Natural Selection • Species change over long periods of time • Enough differences accumulate that new species form • All species came from one common ancestor (this was a bit of a leap of faith on his part) • This is more of the theoretical part • The environment causes populations to change over time

  10. Natural Selection • Individuals compete for resources and mates • Certain genes cause some individuals to outcompete others • That means these genes become more common and less favorable genes become less common or disappear • Over long periods of time these favorable genes accumulate and the population will be very different than its ancestors

  11. Natural Selection • Traits that help individuals survive and reproduce become more common • Incredibly complex traits come about after millions to billions of years of small changes

  12. Example http://www.youtube.com/watch?v=iraaygtYSYk&feature=related

  13. What is Advantageous Depends on the Environment • White moths were common in London before industrial evolution • After- soot covers most of the city and black moths become common

  14. Some of The Evidence • Biogeography • Homology • Fossils • DNA/Protein analysis

  15. Biogeography • Animals are closely related to those around them • Similar looking animals from other continents are NOT related

  16. Fossils • The order in which you find fossils in the soil matches expected evolutionary history • Ancient fish Ancient Amphibians Ancient reptiles ancient mammsls • Intermediate species have been found • i.e. fish with legs

  17. Homology • The anatomy of species that we believe share ancestors are similar • Bat wings are much, much more similar to a human arm than to a bat wing

  18. Leftover Structures • Many organisms have structures they don’t use from their ancestors • Whales and snakes have leg bones • Human appendix? • Ear point in humans

  19. More Homology • The development of closely related animals is very similar • Humans still have gills and a tail early on in development

  20. DNA Evidence • The newest, strongest and most complete evidence for evolution

  21. Evidence of Common Descent • Some genes have been conserved in all living things • All living things use DNA and have some similar processes in common (i.e. DNA mRNA protein)

  22. DNA Evidence for Relationships • Closely related species share more genes • But there are differences where mutations have occurred

  23. DNA Also Provides a Mechanism • We know that mutations in the DNA do occur (Darwin didn’t know this) • So new genes come about or new combinations of genes come about • If they are advantageous, they become common (i.e. wings) • If they are not they disappear

  24. Classifying Species • Attempt to figure out when they diverged or split from a common ancestor • Use a variety of sources of evidence – look at DNA, proteins, fossils, where they live etc. • Fewer differences = more closely related • The advent of DNA technologies has VASTLY changed how we view the tree of life • Fungi are more closely related to animals than to plants!

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