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5.4 Evolution

5.4 Evolution. IB Biology. Evolution. The cumulative change in the heritable characteristics of a population Cumulative – small changes over time (many generations) Heritable – gene-controlled factors/traits Population – not an individual

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5.4 Evolution

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  1. 5.4 Evolution IB Biology

  2. Evolution • The cumulative change in the heritable characteristics of a population • Cumulative – small changes over time (many generations) • Heritable – gene-controlled factors/traits • Population – not an individual • Life on Earth is unified by its common origins • Species can evolve • New species arise from preexisting ones • http://www.johnkyrk.com/evolution.html

  3. Charles Darwin • Father of Evolution • The Origin of the Species, 1859 • HSM Beagle • Studied finches in Galapagos islands

  4. Evidence for Evolution – TOK Link

  5. Evidence for Evolution http://www.brainpop.com/science/ecologyandbehavior/humanevolution/

  6. Evidence for Evolution • Fossil Record • Remains of extinct species provide evidence that species are continuously evolving • Shows a change in species over time http://www.brainpop.com/science/ecologyandbehavior/humanevolution/

  7. Evidence for Evolution • Homologous Structures • Structures that may look different and perform a different function, but have a “unity” in structure (eg. bone position) • Common ancestry • Look different because they have adapted to perform different functions (adaptive radiation)

  8. Pentadactyl limb (five digits) Pentadactyl limb (five digits)

  9. Vestigial Structures • Darwin called them “rudimentary organs” • Reduced structures that serve no function • Lost function and are gradually being lost • Appendix in humans • Used to be larger sac to digest cellulose • Pelvic bone in baleen whales • Support upright weight • Walking

  10. Evidence for Evolution • Selective Breeding • Humans have selected desirable traits in domesticated animals for centuries • Farmer notices a favourable trait, individual allowed to breed • May also influence other characteristics • Farmer notices a negative characteristic, not allowed to breed • Called artificial selection • Eg. Cows • Jersey - milk • Angus - beef

  11. Evolution Video • Great Transformations

  12. Comparative Embryology

  13. Homework • Page 184: DBQ • Page 189: Thinking about science (cover the answers on the side)

  14. Populations • Populations tend to produce more offspring than the environment can support • Consequence of overproduction of offspring is a struggle to survive • Think back factors that limit population growth

  15. Variation • Variation - A marked deviation from the typical form or function

  16. Variation • Crossing Over (prophase I) • Creates new combinations of alleles on a chromosome • Recombination • Random Assortment (metaphase I) • How chromosomes line up at the equator • ↑ chromosome number = ↑possibilities • 2n = 223= 8, 388, 608 possibilities • Random Fertilization • Any sperm cell can randomly fertilize the egg cell • Faster swimmer!!

  17. Evolution in response to environmental change • Antibiotic Resistance in Bacteria • Environmental change: methycillin antibiotic (drug)

  18. Antibiotic resistance in bacteria Methycillin

  19. Antibiotic resistance in bacteria Methycillin resistant Methycillin susceptible

  20. Antibiotic resistance in bacteria Take your prescription until the very end!!!

  21. Evolution in response to environmental change • Peppered Moth (Bistonbetularia) • Environmental change: soot from pollution, industry • typica stood out • Predation • Population declines • carbonariacamoflauged • Little predation • Survive to pass on trait and population increases • Reversing because of clean air acts • http://www.techapps.net/interactives/pepperMoths.swf

  22. Evolution in response to environmental change • Galapagos finches • Darwin visited Galapagos islands in 1853 • Observed the size and shape of beaks many species of finches • Finches on each island had different selection pressures, and over the years had adapted to suit own island – own species • Common ancestry • Environmental change: • Food supply • http://www.sepa.duq.edu/finches.html • http://www.brainpop.com/science/ecologyandbehavior/naturalselection/

  23. Natural Selection • Variation produces different traits • give an advantage or disadvantage • Inherited characteristics affect the likelihood of an organisms survival and reproduction • Traits that give an advantage are passed on to the next generation • adaptations • Over time, the proportion of the population with the advantageous trait will increase (and those with a disadvantage will decrease) • “Survival of the fittest”

  24. Opposing Viewpoints • Published in The Economist, 2009 Friends: http://www.youtube.com/watch?v=cXr2kF0zEgI

  25. HW: IB Questions • Explain evolution of a species by natural selection in response to evolutionary change (8 min) • Explain two examples of evolution in response to environmental change (9 min) • Optional: Evolution extra credit assignment • Read the Survival of the Sneakiest comic on Edline. • Explain it in one paragraph using ecology vocabulary

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