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What is evolution, really?

What is evolution, really?. Section 15.1. The Theory of Evolution. Evolution The slow and gradual change of species over time. Describes the history of a species: Why adaptations appear Where species come from How life has changed on Earth. Isn’t Evolution Just a Theory?. Remember:

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What is evolution, really?

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  1. What is evolution, really? Section 15.1

  2. The Theory of Evolution • Evolution • The slow and gradual change of species over time. • Describes the history of a species: • Why adaptations appear • Where species come from • How life has changed on Earth

  3. Isn’t Evolution Just a Theory? • Remember: • A theory is not just a guess about something. • A theory is an explanation that has been supported by a large body of evidence. • A fact is some piece of DATA that is known . • A theory ties all the facts together into a cohesive, testable model. • Video • Evolving Ideas #1: Isn’t Evolution Just a Theory

  4. Early Influences • Lemark • Described the evolution of acquired traits. • A giraffe’s neck is long, because: • A giraffe stretched its neck for the highest branches. • Through successive generations, the neck came to be modern length.

  5. Early Influences • Charles Lyell • Wrote the book on Geology. • Described the early ideas about plate tectonics and the movement of the continents. • Thomas Malthus • An economist that wrote The Principle of Population. • Proposed that the population was growing so fast, we would soon exceed food supply.

  6. Early Influences • Artificial Selection • For thousands of years, humans have breed animals for desired traits. • Successive generations would inherit such traits • Pigeons, Cows, and Dogs The Breeding of Dogs (HHMI)

  7. Charles Darwin • The English Naturalist born in 1809. • Travelled the world on the HMS Beagle • Collected specimens from around the world and brought them home to study. • Specifically, the specimens from the Galapagos Islands

  8. Charles Darwin • His Observations • Many species produce large numbers of offspring. • A large population leads to greater competition. • The organisms better suited to their environment are more likely to survive. • Only organisms that survive can reproduce.

  9. Charles Darwin • He spent 30 years developing his ideas. • Analyzing data • Debating friends • Meanwhile, Alfred Russell Wallace developed a similar theory in Malaysia

  10. Charles Darwin • Finally, in 1859 he published is famous book On the Origin of Species by Means of Natural Selection • The book described two key ideas: • Common Descent • Natural Selection

  11. Charles Darwin • The Final Sentence of On the Origin: There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

  12. Pop Quiz!!

  13. Pop Quiz!!! • What English Naturalist receives the most credit for the Theory of Evolution? • What was the name of the ship on which he travelled the world? • At what group of 14 volcanic islands did the crew make a pit stop? • What is the name of his famous book? • What are the two main ideas described within the famous tome?

  14. Evolution of the Eye To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.

  15. Common Descent • Species show similar features because they share a common ancestor. • The more similar the species, the more recent the common ancestor. • The more distant the relationship, then the more difference appear. • Called the Tree of Life

  16. The Silver Fox Experiment

  17. The Silver Fox Experiment Wolf Dog Fox Dox? 60 ya 10,000 ya 3,000,000 ya

  18. Natural Selection • Overproduction of Offspring • Produce more children than can survive. • Variation among individuals • Each possess different traits • Competition for resources • Food, space and mates are scarce. • Differential success and reproduction • Certain traits might help organisms survive more and reproduce more Desert Pocket Mouse (HHMI)

  19. Ancestral Population

  20. A Mutation Arises

  21. Without a pressure, mutation drifts through the populations

  22. Selective Pressure

  23. Predation reduces the population of brown mice.

  24. A Changing Environment

  25. Selective Pressure

  26. A Changing Environment

  27. Green Mouse Brown Mouse Mixed Phenotypes Ancestral Population

  28. Natural Selection Requires: • Overproduction of Offspring • Variation among Individuals • Competition for Resources • Differential Success Its the Populations, not the Individuals, that evolve!

  29. Finish the Natural Selection Lab from Wednesday 15 minutes End

  30. What are the Facts of Evolutionary Theory? Section 15.1

  31. Fossil Evidence • Fossil Record • Earliest evidence which records the history of life on Earth. • Life on Earth has changed over time. • Camel Evolution • Whale Evolution • Tetrapod Evolution

  32. Adaptations • Structural Adaptations • Help the organism survive or to find food. • These adaptation arise slowly over time. • Blind Mole-rats • Hummingbirds • Polar Bears

  33. Adaptations • Camouflage • Allows an organism to blend into its environment. • Stick Bugs, Leaf Frogs, Coloring • Mimicry • Allows a harmless species to appear like a dangerous one. • Butterflies, Snakes, etc. Monarch Butterfly Coral Snake- Poisonous Viceroy Butterfly King Snake- NOT Poisonous David Gallo’s Amazing TED Talk

  34. Adaptations • Physiological Adaptations • Changes in an organism’s metabolic processes. • Antibiotic-resistance leads to Super Germs

  35. Anatomical Evidence • Homologous Structures • Structural features with a common evolutionary origin. • Similar in arrangement or function. • Tetrapod Limbs

  36. http://www.cdkenterprises.com/roomdecor/Whimsical-Wings/images/Monarch.jpghttp://www.cdkenterprises.com/roomdecor/Whimsical-Wings/images/Monarch.jpg http://www.lilytherese.com/Flying_Eagle1.jpg Anatomical Evidence • Analogous Structures • Structures with a similar function but different evolutionary origins. • Arose under similar evolutionary pressures. • Bird and Insect Wings Human Thumb Panda Thumb- Analogous Chimp Thumb- Homologous

  37. Anatomical Evidence • Vestigial Structures • A structure in a present-day organism that no longer serves its original purpose. • It continues to be inherited, but is unused by the individual. • Whale hip bones, Eyes in blind mice

  38. Embryology • An embryo is the earliest stage of development in plants and animals. • Vertebrate animals go through similar stages during embryonic development. • Pharyngeal Pouches, Yolk Sacs, and Tails

  39. Biochemistry • Conservative Protein Structure • The shape of a protein determines its function. • Many proteins are conserved among different species. • Cytochrome C is extremely similar in all animals.

  40. Biochemistry • Conservative DNA • All living things contain DNA • Organisms with fewer differences in DNA, are more related. • DNA can construct elaborate evolutionary relationships. • Human and Chimp DNA is 98% the same Giant Panda= Related to Bears Red Panda= Related to Raccoons

  41. Biochemistry • Fossil Genes • When genes are no longer used they don’t just disappear from the genome • They accumulate mutations that have no effect on the survival • Humans have pheromone genes and vitamin C genes

  42. Downside to Evolution

  43. So how do we know that Evolution takes place?

  44. Pop Quiz!!

  45. Just Kidding!!!

  46. What Mechanisms Drive Evolution? Section 15.2

  47. The Modern Synthesis • Combines evolution with every other aspect of biology: • Classification, ecology, cells, development, and especially genetics. • Biology = Evolution

  48. Population Genetics • Populations, not individuals, evolve! • Individuals in the populations show different phenotypes because they possess different alleles. • Different alleles arise through mutations to the DNA. • The DNA is inherited by offspring.

  49. Population Genetics • The Gene Pool • The collection of possible alleles in the population • Allele Frequency describes the percentage of each allele in the population. • Evolution results from changes to the allele frequency. • Genetic Equilibrium • When the allele frequency does not change for a long period of time • This stable population stays the same

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