1. Topic 3 Biodiversity & Conservation 3.2 Origins of Biodiversity

2. Evolution by Natural Selection DarwinDarwin proposed his theory in The Origin of Species by Means of Natural Selection (1859) “Survival of the Fittest” Main idea: More favorable genes increase in frequency in successive generations, and fewer unfavorable genes survive.

3. Darwin’s Voyage

4. Evolution by Natural Selection 4 observations about nature: 1. Overproduction More offspring produced than will survive to maturity. 2. Competition Environment can’t support everyone… competition for resources disease

5. 3. Variation Individuals have unique combinations of traits that make them more/less “fit” for their environment. 4. Differential reproductive success Those individuals with the most “fit” traits for their environment are more likely to survive, reproduce, and pass their traits on to the next generation!

6. Natural Selection Summary Overproduction  Competition Variation  Differential Reproductive Success Comp + Diff Repro Succ  Natural Selection

7. Types of Natural Selection

8. Directional Selection One extreme of a specific trait is more advantageous than both the other extreme and the average trait. It pays to be different!! Examples: –Peppered Moth –Bacteria that are genetically resistant to some antibiotics.

9. Stabilizing Selection Tends to eliminate individuals on both ends of the genetic spectrum. It pays to be average!! Occurs when the environment changes little and most species are well-adapted. Often mistaken for no selection Example: birth weight

10. Diversifying (Disruptive) Selection Individuals at both extremes are selected for, average is selected against. It pays to be either extreme!! Examples: –Green vs. Brown Anole –Darwin’s Finches

11. Darwin’s Finches Each finch species is specialized for a particular lifestyle (structure of their beaks) An adaptation to their specific diets seed eaters, cactus eaters, insect eaters, fruit eaters) and different from finches on the South American mainland. 14 species of Galapagos finches decended from a single ancestor- one or a small population of finches that originally colonized the Galapagos.

13. Types of Species Evolution

14. Convergent Evolution Two different species who live in the same type of habitat evolve to have similar traits. Example: Sharks and dolphins –Dolphins are mammals, Sharks are fish. –So how did they convergently evolve? They look the same and act in similar manners because they both live in the ocean, so they’ll need similar traits!

15. CONVERGENTEVOLUTION

16. Convergent Evolution

17. Divergent Evolution Two populations of the same species who live in different places evolve to become different… Example: Birds –Now we have penguins & puffins!! –So how do they divergently evolve? Penguins live where it’s cold and where there’s lots of water. There’s more food for them in the water, so they evolved to “fly” underwater. Puffins live where it’s slightly warmer. There’s lots of food sources outside of the water, so they continued to fly normally.

18. Again… Darwin and the birdies Adaptive Radiation  process by which ancestral species evolve into a number of diff species **special type of divergent evolution**

19. Divergent Evolution

21. Coevolution Two species that interact closely may change in a similar fashion Example: a wolf and a rabbit –How are they related in an ecosystem? –So how do they co-evolve? If the rabbit evolves to be faster, the wolf will have to keep up, so it must also evolve to be faster. Why does he want to eat me? I am sooo cute! Yummy…. Rabbit for dinner! I will run faster then… He is fast! I have to run faster!!

22. Animal/Plant Coevolution The gracefully curved bill of the ‘I’iwi enables it to sip nectar from flowers of the lobelia. The ‘I’iwi bill fits perfectly into the long tubular lobelia flowers.

23. Coevolution in Plants Acacia Tree & Ant * Tree has large hollow thorns that provide a protected nesting site for stinging ants. Ants attack any animal and clear away vegetation surrounding the tree which helps the tree get the sunlight it needs.

24. Caterpillars & Plants Plants may have poisonous chemicals that prevent insects from eating them. Some caterpillars have the ability to resist these poisons. They can feed on plants that other insects can’t As the plant adapted by producing poisonous chemicals, the caterpillar adapted by resisting them.

25. Coevolution

27. Natural Selection & Species Evolution THERE IS A BIG DIFFERENCE!!! What is it???

28. Nat Select  Evolution  Speciation Remember from earlier: –Overproduction  Competition –Variation  Differential Reproductive Success –Comp + Diff Repro Succ  Natural Selection So…….. NAT SEL + GENERATIONS  EVOLUTION SPECIATION: Evolution that causes a species to change enough to not be able to interbreed anymore

29. Speciation occurs from: Physical Barriers –Gene pool no longer mixes, so two populations develop in different directions –New mountain range, river flow change, etc Land Bridges –Allow species to invade new areas –Sea level falling, continental drift, etc. Continental Drift –Cause climates to shift & food supplies to change –Ex: Antarctica was tropical, has now lost its forested area

30. PHYSICAL BARRIERS cause GEOGRAPHIC ISOLATION leading to SPECIATION Grand Canyon World Isolation

31. Group Discussion How can Plate Tectonics act as a speciation force? What type of Natural Selection would this be? What type of Species Evolution would this be?

32. Continental Drift Continental Drift- The continents have moved. They were together in Pangaea. Began to separate ~200 MYA. Proposed by German scientist Alfred Wegner (1912) Hi! I'm Alfred! SUPPORTING EVIDENCE: - Puzzle-like continental shape - Rock correlations - Fossil correlations - Climatic data

33. 1. “Puzzle” - like fit to the continents EVIDENCE FOR CONTINENTAL DRIFT CLICK HEREHERE FOR ANIMATION

36. 2. Fossil Evidence - Animal and plant fossils have been found on distant continents

37. 3. Rock Evidence Appalachian Mountains share the same rock features as mountains in Greenland & Europe

38. 4. Climatic evidences: Coal in Antarctica There's coal in Antarctica!!! What's the big deal? Isn't coal just a rock? 1. Coal is made from swamp plants that live in rainy, temperate climates 2. These plants could NEVER have lived in a climate like Antarctica's!! 3. CONCLUSION: It must have been nearer to the Equator once

39. 4. Climatic Evidence: Glacial Deposits - Found in Africa, India, Australia & South America - CONCLUSION: must have been nearer to the South Pole once!

40. Continental Drift VS Plate Tectonics Continental Drift: the continents used to be together in Pangaea, but have slowly drifted apart. Why was Alfred Wegener not believed? He couldn’t explain WHY! He died in 1930.  WHY do the continents drift? …PLATE TECTONICS!!!

41. Earth's Structure Three main sections: crust, mantle, core Demo:Plasticity

43. PLATE TECTONICS Movement of lithospheric plates carrying the continents. Plate Boundary: Where two plates meet and interact. Intense geologic activity occurs here! Plates are made of lithosphere and float on asthenosphere (magma) Plate motion is due to convection currents in the asthenosphere.

44. Three types of Plate Boundaries: (1) DIVERGENT BOUNDARY -plates move apart -creates a rift valley -magma is exposed at the boundary -magma is exposed at the boundary -constructive or destructive margin?

45. Divergent (oceanic)

46. Divergent (continental)

47. (2) Convergent Boundary: plates come together 3 types: a. Continental-Continental: -creates mountains (Appalachian & Himalayas) b. Continental-Oceanic: -oceanic subducts (> density) to create a trench & land volcanoes (West Coast US) c. Oceanic-Oceanic: -older plate subducts (>density) to create a trench & volcanic islands (Japan, Philippines) SUSUBDUCTION ZONE: One plate is forced below another. Constructive or destructive margin?

48. Convergent Continental-Continental

49. Convergent Oceanic-Continental

50. Convergent Oceanic-Oceanic

51. (3) Transform Boundary: plates slide past one another -creates a fault line

52. Transform

53. Where are the Constructive and Destructive Margins? Click for ANIMATION!

54. What kind of boundary is this... convergent, divergent, or transform? Is it constructive or destructive? The arrows represent what process?

56. Geologic Time Scale Earth is 4.6 BY old First life: bacteria, 4 BYA Dinosaur Extinction 65 MYA Humans: 200,000 years ago Currently in: –Phanerozoic Eon –Cenozoic Era –Quaternary Period –Holocene Epoch

57. Background vs Mass Extinctions Background Extinction: natural species extinction. Expected to be about 1 species per million species per year (that’s about 10-100 species per year) Contrast with Mass Extinction: many species go extinct at the same time.  Our current extinction rate is significantly higher than 1species/million species/year … Mass Extinction!!!!

58. Past Mass Extinctions Many species die at the same time. They cannot withstand significant changes in conditions from: –Rapid climate changes –Some natural disaster (volcanic eruption, meteor impact) There have been 5 major mass extinctions. Most recent historical mass extinction was 65 MYA when the dinosaurs went extinct. Due to: –Meteor impact off the Yucatan Peninsula –Series of long-term volcanic eruptions in India –Both ejected dust into atmosphere (↓photosynthesis, breaking down food webs)

59. Current Mass Extinction We may now be in a sixth mass extinction… The Holocene Extinction Event. –Anthropogenic –Began ~10,000 years ago with large mammal extinction (mammoth, etc) from hunting –Accelerated greatly in last century due to modern humans Transform environment (cities, roads, industry, agriculture) Overexploit other species (fishing, hunting, harvesting) Introduce invasive species (may have no predators) Pollute the environment (may kill species directly or indirectly)

60. Extinction Rebounds After each past mass extinction, there was a rebound of species. The rebounds take 5-10 million years. Humans have made such a significant impact in such a short time. Would you expect this same type of rebound to occur? If so, would it be faster, slower, or the same?