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Evolution Unit

Evolution Unit. Chapter 15, Darwin’s Theory of Evolution Puzzle of life’s diversity Ideas that shaped Darwin’s thinking Darwin presents his case Chapter 16, Evolution of Populations Genes and variation Evolution as genetic change Process of speciation Chapter 17, History of Life

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Evolution Unit

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  1. Evolution Unit • Chapter 15, Darwin’s Theory of Evolution • Puzzle of life’s diversity • Ideas that shaped Darwin’s thinking • Darwin presents his case • Chapter 16, Evolution of Populations • Genes and variation • Evolution as genetic change • Process of speciation • Chapter 17, History of Life • Fossil record • Earth’s early history • Evolution and multicellular life • Patterns of evolution

  2. Why Care About Evolution? • Curiosity about the origins of life, how all the species came into being, how the living world came into being. • Curiosity about what may happen to the natural world in the future. • Predict what new life forms research will discover in the future. • Evolutionary theory can help predict which strains of flu, AIDS, and West Nile virus will be most deadly next year. • Desire to learn about all life, past, present and future. • Want to pass this biology class and the TAKS test.

  3. Definitions to Know Box 1 • Scientific Theory = a well-supported, testable explanation of phenomena that have occurred in the natural world. • Evolution= change over time, the process by which modern organisms descended from ancient organisms • Is Evolution Fact or Fiction? • Scientists believe it’s Fact. • Proof? • Fossils • Speciation • Geological evidence • DNA evidence • Etc. Box 2

  4. Charles Darwin (1809-1882) • British naturalist famous for his theories of evolution and natural selection. • Like several scientists before him, Darwin believed all the life on earth evolved (developed gradually) over millions of years from a few common ancestors. • In 1831, Darwin took a trip around the world on the ship, the M.S. Beagle, where he collected evidence that led him to propose his famousTheory ofEvolution. Box 3 There’s a huge tortoise lurking behind me, interesting. And he has weird birds on his back. Charles Darwin

  5. Darwin’s Voyage on M.S. Beagle Box 4 Ewww, nasty. I spent 5 years on a ship, can you imagine what that was like? What we all smelled like? Starting point: 1831, England Ending point: 1836, England Did you know there are no rabbits in Australia? No kangaroos in England? No monkeys in North America? No elephants in Alaska? Darwin’s observations showed him there were patterns to the diversity of life on Earth. Organisms are adapted to the environment where they live. Box 5

  6. Fossils Glyptodon = dead Armadillo= alive • Darwin didn’t just observe and collect living animals, he also collected fossils. • Fossils = preserved remains of ancient organisms • This led to questions like…. • “Where did all these organisms go?” “Why aren’t they still here?” “Why do they resemble organisms we have living today?” Box 6 This is too much of a coincidence.

  7. Homo sapiens- existed from about 200 thousand years ago (TYA) to the present Australopithecines- existed between 5 and 2 million years ago Neanderthal man- existed from about 250 to 30 thousand years ago Homo hablis- existed 2.4 to 1.5 million years ago Homo erectus- existed around 1.8 million years ago Do we look alike?

  8. The Galapagos Islands Box 7 Animals Darwin studied: 3. Finches • Giant Tortoises 2. Iguanas Box 7 • The most important, influential stop on Darwin’s trip was the Galapagos Islands • 1000 km west of S. America, a cluster of islands isolated by miles of sea • The islands had different climates, and therefore, had different varieties of animals and plants I’m lonesome George That’s my friend Finchy!

  9. Galapagos Turtles Each turtle lives on a certain island, and their shells are different, island-dependent! Brilliant! Box 8 Pinta Tower Marchena Pinta IslandIntermediate shell Hood Island Saddle-backed shell Fernandina James Santa Cruz Isabela Santa Fe Floreana Hood The shape of each turtle’s shell is different and the different shapes depend on the turtle’s habitat. Isabela Island Dome-shaped shell

  10. Darwin’s Finches Box 10 and 11 The finches of the Galapagos Islands provide a classic example of Adaptive Radiation—the evolutionary process through which a single lineage gives rise to species occupying diverse environmental niches. In one model of how species form, geographical separation leads to evolutionary divergence (growing apart). • Darwin also collected finches, birds, matching their beak and body shapes with different islands- just like the tortoises. • Beak shapes in the finches indicated their type of diet, what they ate, and this told him where they lived Box 9 Tree Finch Ground finch In other words, if you get separated from your own species, you evolve or change in response to your environment.

  11. Darwin’s Finches FYI, each beak is designed for a different purpose. Box 12 Leaves Seeds and Fruit Seeds Insects Grubs Tool using

  12. Scientists Who Influenced Darwin • Discovery of fossils helped shaped the scientists of Darwin’s time • 2 biologists who influenced Darwin were James Hutton and Charles Lyell, theyhelped scientists recognize that: • Earth is many millions of years old (Hutton) • The same natural process happening THEN are still happening NOW (Lyell) • Jean Baptiste de Lamarck • Living things have changed over time • Living things respond to their environments • Through either use or disuse, organisms acquired or lost certain traits during their lifetime, and these traits could be passed on to the next generation Box 13 Lamarck here, nicely done Darwin! Box 14 Box 15 Box 16 Thank you. I’m pretty smart.

  13. Use it or lost it Eeek! It’s the C Gang, they won’t leave me alone! Oh, I’ve GOT to grow that claw! Look, it’s Crabby, what a jerk. Hey, Crabby, you loser! You just wait! I’ll get you one day! Stay away from me! Hi! I’m Crabby. I want to be superior, how can I do that? Ha Ha! Are you scared? Huh? Are you scared you little twerps! The Next Day…… Where are you going? Run away! Run away! I know! I’ll grow a huge claw, and I’ll squash those other crabs! Boy, dad sure did know what he was doing when he developed this huge claw- weapon! Let’s drop him! Yeah, thanks dad!

  14. Thomas Malthus (1798) Thomas Malthus Box 17 • English economist who introduced the concept of human population growth and the problem of too many people, too little space • Populations don’t grow uncontrollably, there is a limit to population growth • Why do some survive and some die? Too many people, too little space, let the shark have her! She’s about to be shark bait. Sharks are perfect predators, perfect killing machines. He has no heart, he’s a mathematician.

  15. What took him so long? 25 years later…. Box 18 • In 1858, Alfred Wallace sent Darwin an essay with the same ideas about evolution! • They presented their work together at a conference, but…. • This pushed Darwin to publish his work, before Wallace • The Origin of the Species • Proposed a mechanism for evolution, called Natural Selection • Presented evidence that evolution has been happening for millions of years You stole MY idea! Cheat! Thief! You’re famous and I’m not! I procrastinated, and came close to losing my chance for fame! And I aged quite a bit. Shut up Wallace, you sore loser. Survival of the fittest and all that.

  16. Artificial Selection and Natural Selection • Adaptation= any inherited characteristic that increases an organisms chance of survival Box 23 Box 19 • Variation exists in nature and animal and plant breeders use this through artificial selection • A farmer may like a see a plant with bigger tomato and use the seeds of that plant for next year’s crop • Or he may breed the two best milk cows to get a cow who is an even better producer of milk • Darwin’s greatest contribution was his concept of natural selection • In the struggle for survival, the most fit- the fastest prey, the strongest predator, the one with the sharpest claws, wins the game of survival. Survival of the fittest. • Fitness= the ability to survive and reproduce in a specific environment Box 20 Box 21 Box 22 How is your fitness? Did you notice how fat Wallace was? NOT fit.

  17. Proof for Evolution • Fossil record = Darwin argued that the fossil record provided evidence that living things have been evolving for millions of years • Geographic Distribution of living species: Descent with modification, says that similar species in similar environments but in different locations, were products of different evolution paths Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara Box 24 Box 25 They all look like rats to me.

  18. Homologous Body Structures Box 26 Homolgous structures all develop from the same embryo tissues but have different functions in the adult organism. • What does Homo mean? • Homo = same, similar • Remember these? • Homozygous- same allele for a trait, tt, TT • Homologous chromosomes- same chromosome, one from mom one from dad Turtle Alligator Bird Mammal Ancient lobe-finned fish

  19. Vestigial organs • Why do we need our appendix? • It’s useless now, but it may have served some function in our past • Vestigial organs = organ with little or no function, left over from the past, ex. appendix Box 27 If you can live without it, with no medical help, then it’s useless!

  20. Ch. 16, Evolution of Populations • Why are we all so different? • Variation in populations is the raw material for evolution • 2 main sources of variation: • Mutations = any change in a sequence of DNA, some are harmful, some are beneficial and some don’t have any effect at all • Gene shuffling = mixing of genesdue to random sexual mating • 23 pairs of chromosomes can produce 8.4 million different combinations of genes • Crossing over during Meiosis Box 28 Box 29

  21. Variation and Gene Pools • Genetic variation is studied in POPULATIONS, not individuals • Members of a population share a Gene Pool • Gene pool = consists of all genes, including all the different alleles that are present in a population • Why? • They descended from acommon ancestor • Relative frequency of an allele = number of times an allele occurs in a gene pool • So, evolution is any change in the relative frequency of alleles in a population Box 29 Box 30

  22. Natural Selection and Speciation Write as much as you want from this paragraph Box 31 • Natural Selection= (Dr. Malone’s definition) when individuals who have what it takes survive and reproduce best; survival of the fittest, it’s a dog eat dog, you got to step on someone else to get where you want to go, world • Founder Effect = when a population shrinks down to only a few members, then rebounds so all of the future members have the “founder’s” genes • Speciation = when natural selection and other random effects lead to the creation of a new species • Reproductive Isolation = populations become reproductively isolated from each other, so it leads to evolution of a new species Box 32 Box 33 Box 34 This is why cats and dogs can’t have cat-ogs, or is it do-cats? Dogats? Cadogs?

  23. Speciation If all our women moved to China, could we continue to interbreed? Ha ha. Don’t think so! It’s too far to fly! Move mountain! Move mountain! Box 35 • Behavioral Isolation = when two populations can interbreed, but their different behaviors, or reproductive strategies, just don’t turn each other on, get it? • Geographic Isolation = two populations are separated by geographic barriers, like mountains or oceans and they can’t interbreed Box 36 Box 37 • Temporal Isolation = two populations are separated by different reproductive times I say go for it!

  24. Ch. 17, The History of Life Box 38 • Paleontologists (pay-lee-un-TAHL-uh-jists) = scientists who study fossils, history written into stone • The fossil record: • Provides evidence about the history of life on Earth • Shows how species have changed over time (evolved) • 99% the species that have lived on Earth are extinct!!!! • Fossils form in sedimentary layers of rock • Fossils at the top are younger than fossils at the bottom, common sense, or relative dating Help! Box 39 Box 40 I’m extinct. There are and will be no others like me, it’s so tragic.

  25. How old are Fossils? Box 43 Half-Life = length of time it takes for ½ of the radioactive atoms in a sample to decay Carbon-12 Carbon-14 6 6 C C 12 14 Box 41 and 42 • Relative dating is comparing fossils with other fossils to see estimate the age of each, but it’s not very precise • Radioactive Dating- calculating the age of fossils based on the amount of remaining radioactive isotopes they contain Do you remember? Isotopes = an element with a different number of neutrons in its atom How many neutrons in C-12? 6 Radioactive!!! How many neutrons in C-14? 8

  26. Geologic Time Scale You are HERE (millions of years ago) Time Era Time Era Time (millions of years ago) Era Period Period Period 290 – 245 360–290 410–360 440–410 505–440 544–505 Quaternary Permian Vendian 1.8–present 65–1.8 145–65 208–145 245–208 650–544 Tertiary Carboniferous Cretaceous Devonian Jurassic Silurian Triassic Ordovician Cambrian Geologists divide the time between Precambrian and the present into 3 eras: Which era does Tyrannosaurus Rex belong to? Jurassic • Paleozoic Era • Mesozoic Era • Cenozoic Era Box 44

  27. Patterns of Evolution Box 45 • Macroevolution = large-scale evolutionary patterns occurring over long periods of time • Important topics in macroevolution: • Extinction = over 99% of all species that have ever lived on earth are now dead, extinct. • Adaptive Radiation = a single species evolving over time into diverse forms that live in different ways Box 46

  28. Macroevolution Cont. Box 47 • Convergent Evolution = unrelated organisms come to resemble one another • Co-evolution = process by which 2 species evolve in response to changes in each other over time -Predator- prey pressures, what food is available, pollination, etc. Box 48

  29. Macroevolution Cont. Box 49 • Punctuated equilibrium = the pattern of long stable periods of time interrupted by brief periods of more rapid change Yikes! I’m outta here! He’s crazy! Hee hee! I’m coming to get you!

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