2. Community Ecology u The study of the interactions between the species in an area.

3. Community Hypothesis 1. Individualistic 2. Interactive

4. Individualistic Hypothesis u H.A. Gleason u Community as a chance assemblage of species because of similar abiotic requirements.

5. Interactive Hypothesis u F.E. Clements u Community as a linked assemblage of species that function as an integrated whole.

6. Predictions u Individualistic - fuzzy borders u Interactive - sharp borders u Robert Whittaker – tested the two ideas against each other.

8. Results u If abiotic factors form a continuum, then borders are fuzzy. u Individualistic Hypothesis is correct.

9. Comment u Abiotic factors may form sharp borders. u Ex: soil types u Result – the Community may look very much like the Interactive Hypothesis.

10. Interspecific Interactions u Interaction between species. u May be positive, negative, or neutral. u Ex: 1. Coevolution 2. Predation 3. Mimicry 4. Competition 5. Symbiosis

11. Coevolution u When two species have reciprocal evolution to each other. u Ex: u Flowers and their pollinators.

12. Predation (+/-) u Predator and prey relationships. u Ex – Lynx and Hares

13. Predation u Often results in interesting defenses or adaptations. u Ex: u Plant defenses u Cryptic coloration u Aposematic coloration

14. Cryptic Coloration u A passive defense where the prey is camouflaged against its environment.

15. Aposematic Coloration u The use of conspicuous colors in toxic or unpalatable organisms to warn off predators. poison arrow frogs

16. Mimicry u Defense mechanism where the mimic has a resemblance to another species, the model. u Types: u Batesian u Mullerian

17. Batesian Mimicry u Palatable species mimics an unpalatable model. Hawk moth larva Snake

18. Mullerian Mimicry u Two unpalatable species resemble each other. Cuckoo Bee Yellow Jacket

19. Competition u When two species rely on the same limiting resource. u Intraspecific competition usually more severe than Interspecific competition. u Why?

20. Competitive Exclusion Principle u Predicts that two species with the same requirement can not co-exist in the same community. u One species will survive and the second will go extinct.

21. Ecological Niche u The n-hyperspace of requirements for a species. u How a species “fits into” an ecosystem. u Species can not have niche overlap, the Competitive Exclusion Principle

22. Niche Types 1. Fundamental - what a species is theoretically capable of using. 2. Realized - what a species can actually use.

24. Resource Partitioning u A way that species avoid niche overlap by splitting up the available resources. u Ex: Anolis lizards

25. A. distichus A. insolitus

27. Symbiosis u When two different species live together in direct contact. u Types: 1. Parasitism 2. Commensalism 3. Mutualism

28. Parasitism (+/-) u Parasite harms the host. u Parasites may be external or internal. u Well adapted parasites don't kill the host.

29. Parasitic behavior: A female Nasonia vitripennis laying a clutch of eggs into the pupa of a blowfly (Phormia regina)

30. Commensalism (+/o) u One partner benefits while the other is unchanged. u Ex. – Cattle and Egrets

31. Mutualism (+/+) u Both partners benefit from the interaction. u Ex: Pollinators and flowers Acacia Tree and Ants

32. Succession u Changes in species composition over time.

33. Succession Stages u Sere: unstable stage usually replaced by another community. u Climax: stable stage, self-reproducing.

34. Succession Types 1. Primary 2. Secondary

35. Primary Succession u Building a community from a lifeless area. u Ex: volcanic islands glaciated areas road cuts

36. Comment u The first example of primary succession was worked out on the Indiana Dunes. u Stages: u Open Beach u Beach Grasses u Conifers (Junipers and Pines) u Oaks u Beech-Maple forest (Climax)

37. Secondary Succession u Where a community has been disturbed and the soil is mostly intact. u Ex: u Cutting down a forest u Blow-outs on the Dunes

38. Causes of Succession 1. Autogenic Factors 2. Allogenic Factors

39. Autogenic Factors u Changes introduced by the organisms themselves. u Ex: toxins acids

40. Allogenic Factors u Outside disturbances u Ex: Fire Floods

41. Prairie Succession in Oklahoma - Stages 1. Annual Weeds 2. Triple-Awn Grass 3. Bunch Grass 4. Climax: Tall-grass Prairie

42. Annual Weed Stage u Lasts 2-3 years. u Very robust growth (1-2 m). u Species: Sunflower Pigweed Lamb's Quarter

43. Annual Weed Stage

47. Triple-Awn Stage u Lasts 10 - 50 years. u Very poor growth (5-12 cm). u Species: Triple-Awn Grass

48. Triple Awn Stage

49. Question u How can Triple-Awn replace the more robust annual weeds?

50. Allelopathy u The release of chemical inhibitors into the environment. u Sunflower: autotoxic u Triple Awn: tolerant

51. Triple-Awn u Inhibits Nitrogen fixing bacteria species u Result: soil N stays low which stalls succession.

52. Bunch Grass Stage u Lasts 20 - 100 years. u Good growth (30-50 cm). u Species: Little Bluestem

53. Bunch Grass Stage

54. Succession Causes u Bunchgrass eventually shades out Triple-Awn, releasing the inhibition of the nitrogen fixers. u Result: soil fertility increases, allowing the next group of species to invade.

55. Climax Prairie Stage u Lasts centuries if maintained by fire. u High growth (up to 2 meters). u Species: Big Bluestem, Indiana Grass, Switch Grass, Little Bluestem

56. Tall Grass Prairie

58. Question u Stages 3 and 4 are the best for cattle grazing. u Normal succession takes 20 - 50+ years. u Can the time needed for restoring the prairie be decreased?

59. Solution u Add more N to soil (NH 4 + ) u Seed climax species u Result: prairie in 3-10 years. u Maintain the prairie by burning.

60. Upland, IN Prairie

63. Point u If you understand the causes and controlling factors of succession, you can manipulate them.

64. Biogeography u Study of the past and present distributions of individual species and communities.

65. Range Limitations 1. Lack of dispersion. 2. Failure to survive in new areas. 3. Retraction from former range area.

66. Proof u Fossil Evidence u Pollen Studies u Transplant Experiments

67. Islands u Special cases in Biogeography. u Must be colonized from other areas.

68. Island Species Factors u Island size. u Distance from mainland.

71. Island Size u Small islands hold few species. u Why? u Fewer niches available for species to occupy.

72. Distance from Mainland u Closer islands have more species. u Why? u Easier for colonization.

73. Comment u Islands tend to have high numbers of Endemic species u Why? u Adaptive Radiation and Evolution of new species.

74. Summary u Know the two hypothesis of community structure. u Know the various types of interspecific interactions. u Know the Competitive Exclusion Principle and Niche Concept.

75. Summary u Know some examples and causes of succession. u Know how island communities are shaped.