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Evolution by Natural Selection

Evolution by Natural Selection. 10/2/06 ES 100: Environmental Ecology. http://home.comcast.net/~fsteiger/cartoon2.gif. A few more logistics…. From Eric Zimmerman: if you are a double major in ES and EEMB, you may not need to take this class. Field Trip (Wed. before Thanksgiving)

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Evolution by Natural Selection

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  1. Evolution by Natural Selection 10/2/06 ES 100: Environmental Ecology http://home.comcast.net/~fsteiger/cartoon2.gif

  2. A few more logistics… • From Eric Zimmerman: if you are a double major in ES and EEMB, you may not need to take this class. • Field Trip (Wed. before Thanksgiving) • Will take about 2 hours (8-9:50). • Transportation provided, but self-guided field exploration • You can do it BEFORE-hand, on your own, if you prefer • Midterm #2 (aka Final Exam) • Add codes: I actually have them now, come see me. • Section assignment this week: check course website!

  3. Recap of Intro. Lecture • Definition of ecology • Ecology vs. Environmentalism • Reductionism vs. Systems Thinking • Scientific Method: Case study of Lake Apopka Alligators • Hypotheses must be testable • A hypothesis can be disproved, yielding support for the ‘alternative’ hypothesis. • A theory is the highest level of scientific understanding

  4. Organization within Ecology Ecosystem Ecology  Community Ecology  Population Ecology  Physiological Ecology

  5. The Classification of Living Things Kingdom:Animalia Phylum:Chordata Class:Mammalia Order:Primata Family:Hominidae Genus:Homo Species:Sapiens

  6. Roots of Ecology • Carl von Linné (mid 1700’s) • classification of living things • Alexander von Humboldt (early 1800’s) • botanical geography • Charles Darwin and Alfred Wallace 1850 • animal geography • theory of evolution by natural selection • Ernst Haeckel 1866 • coined the term “ecology” • Edward Suess 1875 • “biosphere” as the condition that promotes life: it includes plants, animals, and non-living things • Arthur Tansley 1935 • “ecosystem” concept: interaction between living and non-living entities in the biosphere

  7. Theory of Evolution by Natural Selection • Natural selection is the mechanism that explains evolution • Natural Selection: scale = individual • Evolution: scale = many generations

  8. Temporal Scale

  9. Theory of Evolution by Natural Selection • Natural selection is the mechanism that explains evolution • Natural Selection: scale = individual • Evolution: scale = many generations • Darwin’s observations: • Organisms produce more young than can survive. • All species exhibit genetic variability (from mutation and random combination of parent’s genes). • Individuals with traits most suited to environment most likely to survive. • Only survivors contribute to the gene pool. • Theory: Lineages with most appropriate biological programming (genes) for current environmental conditions will leave the most descendants.

  10. Bush, page 7: “Sickle-cell anemia, Down’s syndrome, and color blindness are heritable, and each would reduce an individual’s chance of survival in a wild human population”

  11. When is Mutant Sickle-cell Gene Desirable? www.sicklecelldisease-il.org/.../ what/how.html

  12. Natural Selection and Physical Appearance

  13. Optimal Foraging Theory • Organisms that ‘forage’ most efficiently will be more likely to reproduce (improve fitness) • Thus, natural selection favors optimal foraging. • Cost/benefit analysis • What is foraging? • What do plants and animals forage for? police.ucsb.edu/ crime_prevent.html

  14. Experimental Evidence for Optimal Foraging Would ‘field’ observation match experimental results?

  15. Natural Selection and Biochemical Traits

  16. Testing Hypotheses:Observation vs. Experimentation • Experimentation: Manipulate system by creating experiments • Strength: control variables • Weakness: not realistic • Observation: • See patterns in the field • Strength: grounded in reality • Weakness: mechanistically weak

  17. Natural Selection and Behavior

  18. Are Human’s Exempt from Natural Selection? SWEATY T-SHIRT EXPERIMENT: http://www.pbs.org/wgbh/evolution/library/01/6/l_016_08.html

  19. Defining ‘evolution’ Scientific Definitions: • All the changes that have transformed life on earth from its earliest beginnings to the diversity that characterizes it today –Neil Campbell • The origination of species of animals and plants … –O.E.D. Common Usage: • A process of continuous change from a lower, simpler, or worse to a higher, more complex, or better state –Merriam-Webster’s Dictionary From a scientific point of view, evolution is just how new species come about

  20. Humans as an Evolutionary Endpoint?

  21. Theory of Evolution: Criticisms • Microevolution is generally accepted, but macroevolution is hotly debated • How does evolution add information to a genome to create progressively more complicated organisms? • How is evolution able to bring about drastic changes so quickly? • How could the first living cell arise spontaneously to get evolution started? Pakicetus Ambulocetus Basilosaurus Humpback

  22. Section this Week Internet assignment for section this week: • Visit course website • Follow “Evolutionary Feast” link • Prepare (typed) assignment and bring to section • Bring food to section (can bring a form of the fruit/vegetable- chocolate instead of cocoa beans)

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