1. Chapter 7 Community Interactions

2. Let’s get ready to ruuuuumble!

3. Community Community: populations of all species living and interacting in an area at a particular time

4. Four Characteristics of Community Structure Physical Appearance: size and distribution of its population and species

5. Four Characteristics of Community Structure Species Diversity/Richness: number of different species

6. Four Characteristics of Community Structure Species Abundance: number of individuals of each species

7. Four Characteristics of Community Structure Niche Structure: number of niches, how they compare, and how they interact

8. Differing Physical Appearances Patch Effects: most large communities usually consist of a mosaic of vegetation “patches”

9. Differing Physical Appearances Edge Effects: differences in physical appearance at boundaries between ecosystems

10. Edge Effects

12. Ecological Niche Niche: role an organism plays in an ecosystem niche is like an "occupation“ – a species’ interactions with habitat and other organisms (their role in food web) © Brooks/Cole Publishing Company / ITP

13. Ecological Niche vs. Habitat Habitat: actual location where an organism lives habitat is like an "address" © Brooks/Cole Publishing Company / ITP

14. Generalists vs. Specialists © Brooks/Cole Publishing Company / ITP Generalist Species have broad niches, can live many places, use a variety of resources e.g., dandelions, cockroaches, coyotes, humans Specialist Species have narrow niches, live only in specific places e.g., spotted owls, giant pandas

15. Native Species Native Species: species that normally live & thrive in a particular ecosystem Nonnative Species: (also called exotic, invasive, or alien species) originate in other ecosystems; deliberate or accidental introduction by humans causes problems e.g., "killer bees”, imported from Africa to Brazil to increase honey production; displace native bees © Brooks/Cole Publishing Company / ITP

16. Indicator Species Indicator Species: species that serve as early warnings that a community or ecosystem is being damaged e.g., northern spotted owls are indicators of healthy old–growth forest © Brooks/Cole Publishing Company / ITP

17. Keystone Species Keystone Species: species that play a critical role in an ecosystem Ex: sea otters are keystone species because they prevent sea urchins from depleting kelp beds Ex: flying foxes are keystone species because they pollinate & disperse tropical trees such as durian “The loss of a keystone species is like a drill accidentally striking a power line. It causes lights to go out all over.” – E.O. Wilson © Brooks/Cole Publishing Company / ITP

18. Species Interactions the effects of one species on another may be negative, positive, or neutral five kinds of interactions: POPULATION APOPULATION B COMPETITION PREDATION PARASITISM COMMENSALISM MUTUALISM

19. Interspecific Competition When two or more species use the same limited resource (food, space, etc.) and adversely affect each other – / – niche overlap Ex: fire ants & native ants in North America © Brooks/Cole Publishing Company / ITP

20. High Low Relative population density 024681012141618 Days Each species grown alone Paramecium aurelia Paramecium caudatum No Competition

21. High Low Relative population density 024681012141618 Days Both species grown together Paramecium aurelia Paramecium caudatum Interspecific Competition

22. Resource Partitioning Species with similar resource requirements can coexist because they use limited resources: at different times in different ways in different places © Brooks/Cole Publishing Company / ITP

23. Resource Partitioning Where are the 2 species competing? Why is there no competition here?

24. Resource Partitioning © Brooks/Cole Publishing Company / ITP

25. Resource Partitioning Five species of insect–eating warblers coexist in spruce forests of Maine: feed in different portions of trees consume somewhat different insects © Brooks/Cole Publishing Company / ITP

26. Warblers

27. Predation Members of one species (predator) feed on another species (prey); + / – Ex: lion feeding on zebra © Brooks/Cole Publishing Company / ITP

28. Parasitism One organism (parasite) lives on part of another organism (host) + / – Ex: flea living on a dog © Brooks/Cole Publishing Company / ITP

29. Mutualism Two species interact in a way that benefits both + / + Ex: lichens (algae & fungi) Ex: clownfish & anemones Ex: ants & acacias © Brooks/Cole Publishing Company / ITP

30. Commensalism One organism benefits from another, but neither helps nor harms the other organism + / 0 Ex: epiphyte growing on a tree © Brooks/Cole Publishing Company / ITP

31. Predator-Prey Relationship What do predators do to increase their chances of getting a meal? What do prey do to avoid being eaten?

32. Predator-Prey Relationship Predators get better at catching prey Prey get better at avoiding capture Similar to an “arms race” –Ex: During the Cold War, the US and the USSR tried to intimidate the other with bigger and better weapons

33. Predators Pursuit –Faster (cheetahs) –Better eyesight (eagles) –Hunting in packs (wolves) Ambush –Camouflage (praying mantis) –Mimicry (alligator snapping turtles)

34. Prey Camouflage Ex: walking stick

35. Prey Chemical warfare Ex: skunk

36. Prey Warning colors Ex: poison dart frog

37. Prey Mimicry Ex: king snake

38. Prey Behavior Ex: blowfish

39. Ecological Succession Succession: gradual & fairly predictable change in species composition over time © Brooks/Cole Publishing Company / ITP

40. Primary Succession © Brooks/Cole Publishing Company / ITP

41. Primary Succession Primary Succession: gradual establishment of biotic communities in an area where no life existed before Ex: succession on newly formed islands & after the retreat of a glacier Early Communities: lichens & mosses colonize bare rock Mid Communities: small herbs & shrubs colonize Late Communities: tree species colonize © Brooks/Cole Publishing Company / ITP

42. Primary Succession Type of succession that occurs where there was no ecosystem before Occurs on rocks, cliffs, and sand dunes Pioneer species: the first organism to colonize any newly available area and begin the process of ecological succession

43. Lichens

44. Mosses

45. Parking Lot

46. Secondary Succession © Brooks/Cole Publishing Company / ITP

47. Secondary Succession Secondary Succession: gradual reestablishment of biotic communities in an area where a biotic community was previously present Ex: "old field succession" © Brooks/Cole Publishing Company / ITP

48. Secondary Succession: Mount St. Helens Erupted in 1980 44,460 acres were burned and flattened After the eruption, plants began to colonize the debris

51. Disturbance Disturbance: a distinct event that disrupts an ecosystem or community examples of natural disturbances: fires, hurricanes, tornadoes, droughts, & floods examples of human-caused disturbances: deforestation, overgrazing, plowing disturbance initiates secondary succession © Brooks/Cole Publishing Company / ITP

52. The Circle of Life in Secondary Succession

53. Intermediate Disturbance Hypothesis

54. Ecosystem Stability Inertia: the ability of an ecosystem to resist being disturbed Resilience: the ability of an ecosystem to “bounce back” after it has been disturbed

55. Precautionary Principle We should try to prevent potential harm to an ecosystem even though we don’t understand all of the cause-and-effects “better safe than sorry”