2. Topic 1: Origins of Life

3. Origin of the Solar System Earth is estimated to be ~4.6byo –Radiometric dating of rocks & meteors Nebula: cloud of gas & dust in space Nebula Hypothesis: –Gravity pulled much material together (Sun formed) –Planets: remaining materials

4. Hypothesis: Energy from lightning created organic materials from inorganic ingredients Experimental Set-Up: –Ammonia, H 2 O vapor, Methane, CO 2 gases added –Electricity added (simulate lightning) Result: Amino Acids & later nucleotides

5. Geologic Change Early belief: –Earth ~6,000 years old –Life remained unchanged “New” Observations –Rock layers contained differing fossils –Deeper/older fossils less complex –Environmental changes thought to affect life characteristics

6. Charles Darwin Observed: –Organisms have variations based upon environment –Some variations proved helpful in particular environment Natural Selection: Process where organisms with favorable traits survive and reproduce Major concept in biology published in The Origin of Species (1859)

7. Topic 2: The Theory of Natural Selection

8. Four factors: 1) Overpopulation: more offspring are born than can survive 2) Variation: individuals of a population have differences 3) Adaptation: Some variations allow better survival 4) Descent w/ modification: Offspring w/ advantages will make up more of a population

9. Which rabbit is best adapted?

11. Struggle for Survival Populations do not grow unchecked –Limiting Factors: food, water, shelter, disease, predators Fitness: measure of the ability to survive & produce more offspring

12. Changing Environments Earth’s environments gradually change –Mountains created –Ocean valleys dry up –Rivers create canyons Variations allow some to survive changing environments –With adaptation: more likely to survive & reproduce –Without adaptation: more likely to perish

13. Are new environments being created and destroyed?

14. Topic 3: The Evidence to Support Evolution Theory

15. Defined: Collection of known fossils –Most found in sedimentary rock Age determined by depth –Law of Superposition: new rock forms on top of older rock Evidence Conclusions: –1) Newer fossils are more complex –2) Common ancestors: similarities between ancient & modern life

16. Radiometric Dating Isotopes: atoms of the same element with differing neutrons –Ex: 12 Carbon and 14 Carbon – 12 C = 6 protons + 6 neutrons – 14 C = 6 protons + 8 neutrons 14 C decays at known rate Fossil age determined by comparing ratio of 12 C to 14 C –Wider ratio = older samples

18. (LUCA)prokaryotes Land prokaryotes Unicellulareukaryotes Multicellular plants Fish (first vertebrates) Land plants & fungi Land animals Amniotic egg Dinosaurs extinct Apes 24 Hour Life Timeline Dinosaurs appear Outside links Link 1 Link 2 Scale: 1 minute = 3 million years

19. Show transitions between groups of organisms –Archaeopteryx: shares both bird & reptile features –Basilosaurus: early whale with tiny hind legs –Tiktaalik: early fish with legs Evidence Conclusion : Indicates common ancestry

20. Defined: similar body structures with very different functions Different environments lead to adaptations –Ex: The forelimbs of animals Evidence Conclusion : Indicates common ancestry

21. Defined: Organs which have lost most or all their original function Vestigial Human Parts: –Gill slits = once used to breath oxygen in water –Yolk sac = once used to nourish developing embryo –Appendix = once used to digest plants Evidence Conclusion : Indicates common ancestry

22. Human Embryo w/ Vestigial Structures

23. Snake femurs (leg bones) are vestigial

24. Pelvic bones of whales are vestigial

25. Nictitating membrane is vestigial in humans

26. DNA, proteins, & amino acids compared More related species have more similar chemistry Evidence Conclusion : Indicates common ancestry

27. Different species show similar development Different body plans become noticeable later in development Evidence Conclusion : Indicates common ancestry

28. Antibiotics: chemicals designed to kill bacteria Antibiotic Resistance: Bacteria are adapting to the use of antibiotics –Example of natural selection –Importance: Bacteria infections are becoming harder to treat Fungus Bacteria No bacteria

30. Antibiotic Resistance GoodBad

31. Pesticides: Chemicals designed to kill pests (rodents, insects) Pesticide Resistance: pests are adapting to the use of pesticides –Example of natural selection –Importance: Crops are being destroyed by pests

32. Topic 4: Speciation

33. Speciation Defined: evolution of a new species Species: group of organisms that can interbreed and produce fertile offspring Factors that lead to evolution –Natural Selection –Gene flow –Mutations –Sexual selection –Genetic drift

34. Gene Flow Defined: Movement of genes from 1 population to another Increases variations in a population (new genes introduced) If gene flow prevented –No variations exchanged –Populations isolated –Organisms adapt to their own environment

35. Genetic Drift Defined: Changes in gene pool due to chance (not natural selection) More likely in smaller populations Ex: Natural disaster –Pre-forest fire (left picture): Blue is more advantageous –Post-forest fire (right picture): Due to more red survivors, red has the advantage to reproduce –Survival unrelated to adaptations; Random

36. Geographic Isolation Mountains, rivers, canyons, oceans may separate a population –Gene flow stopped Each population adapts to its isolated environment Over time, genetic differences accumulate between the groups

38. Behavioral Isolation Gene flow prevented due to different mating rituals Populations unable to reproduce Differences accumulate between both groups

39. Temporal Isolation Gene flow prevented due to time interference –1) Mate at different seasons –2) Some active at night (nocturnal) Differences accumulate between both groups

40. Topic 5: Patterns in Evolution

41. Divergent Evolution Defined: closely related species become increasingly different Cause: Different environments Ex: Red fox (forest) vs. Kit fox (desert)

42. Convergent Evolution Defined: different species evolve similar traits due to similar habitats Survival advantage to a particular environment Ex: Tuna (fish) and dolphins (mammals) –Unrelated species with a similar environment (ocean) –Faced similar evolutionary pressures

43. Coevolution Defined: 2 or more species evolve in response to changes in each other Ex: Plants and Insects –Plants: provide insects with nectar –Insect: transfers pollen from one plant to another

44. How Fast Does Evolution Occur? No exact time frame Gradualism: slow & steady change of 1 species into another –Small changes continually build Punctuated Equilibrium: Rapid periods of evolution –Due to sudden environment change –Ex: Mammal diversity exploded after dinosaur extinction Examples of both models exist