1. Community Ecology
Chapter 47

2. Outline Diversity and Composition Models Island Biogeography
Habitat and Ecological Niche
Competition Between Populations
Predator-Prey Interactions
Symbiotic Relationships
Community Development
Community Diversity

3. Community Concept What is a community? Factors to consider
Composition is a listing of various species in the community.
Diversity includes both species richness and species diversity.

4. Diversity and Composition Models
Gleason - Individualistic Model
Each population in community is there because its own particular abiotic requirements are met by a particular habitat.
Clements - Interactive Model
Community is the highest level of organization.
Dependent on biotic interactions.

5. Island Biogeography
MacArthur and Wilson--effects of distance from the mainland and size of an island on community diversity.
Conclusions?

6. Model of Island Biogeography

7. Habitat and Ecological Niche
Habitat -- Home.
Ecological niche ---occupation in the community
Fundamental niche - potential
Realized niche - actual

8. Feeding Niches for Wading Birds

9. Species interactions
Community interactions can be potent selective pressures
Competition
Intraspecific
Interspecific
Predator/Prey
Symbiosis

10. RESULTS OF INTERACTION
(+) organism benefits (how?)
(-) organism suffers (how?)
(0) neutral, no benefit or loss (RU sure?)

11. Competition Between Populations
Intraspecific competition (?)
Interspecific competition (?)
Competitive Exclusion Principle
Resource Partitioning decreases competition.
Can lead to character displacement.

12. Resource Partitioning –more specialized niches

13. Competition Between Barnacle Species

14. Character Displacement in Galápagos Finches

15. Predator-Prey Interactions
Predation
Selective pressure?
Interaction = +, -
Population effects

16. Lynx-Snowshoe Hare Interactions

17. Prey Defenses
Prey defenses -adaptations that thwart the possibility of being eaten by a predator.
Concealment/cryptic coloration/other coloration
Warning coloration
Armor/weaponry
Chemicals
Behavior

18. Gecko?
Gecko

19. Gecko?

20. Stoneplant

21. Walking stick

22. Camouflage in the Anglerfish

23. Mimicry
Mimicry occurs when one species resembles another that possesses an overt antipredator defense.
Batesian – Harmless mimics harmful
Müllerian – Harmful mimics harmful

24. Batesian I: Coral snake or Milk Snake? Would you bet your life on it?
Batesian mimicry

25. Batesian or Mullerian?

28. Vertebrate Eye Mimicry
Similar to Batesian
Can startle or confuse predator

29. Eye Mimicry 2

30. Aposematic (Warning) Coloration
This salamander also has a poisonous chemical.

31. Chemical Defenses
Darling of the Creationists, the Bombardier beetle

32. Chemical Defenses 2

33. Deceptive Coloration Example

35. Sea Hare

36. PHAGOMIMICRY

37. Symbiotic Relationships
Symbiosis close relationship between members of two populations. We’ll be interested in 3:
Parasitism (+, -)
Commensalism (+, 0)
Mutualism (+,+)

38. Parasitism (+, -) Endoparasites Ex? Ectoparasites EX? Social Parasites
Brood parasites
Kleptoparasites

39. Endoparasite Life cycles
Complex, spend different stages in different hosts
Definitive host (primary host)
Intermediate host

41. Tapeworm Life Cycle

42. Schistosomiasis

44. Elephantiasis

45. Brood Parasitism--European Cuckoo
The behavior of the cuckoo hatchling ejecting the host eggs from the nest
The feeding behavior of a foster mother to the cuckoo chick
Figure 37.3B

46. Kleptoparasite—Red Billed Gull

47. Commensalism --+, 0
Shark
(0)
Remora (+)

48. Pseudocopulation
Some orchids offer no nectar at all, but they resemble the female of various insect species. Or at least, resemble closely enough to fool a desperate male of the species – the mimicry is chemical as well as visual. The unfortunate male has to be deceived twice and engage in two acts of pseudocopulation before pollination takes place. Common european species doing this are the bee orchids in the genus Ophrys. In fact some populations of bee orchid seem to be self-fertile in the absence of pollination.
Bee orchid
Ophrys apifera

49. Mutualism Mutualism (+,+) both members of the association benefit.
ADVANTAGES?
EX?

50. Mutualism Between Bullhorn Acacia and Ants

51. Cleaning Symbiosis

52. Community Development
Ecological Succession
A change involving a series of species replacements in a community following a disturbance.
Primary Succession
Secondary Succession
Pioneer Species
Climax Species

53. Secondary Succession in a Forest

54. Succession Models Facilitation Model
Succession in a particular area will always lead to the same type of community
Climax Community—Endpoint of succession
Oldest, most supported

55. Changes in soil structure over time
Soil changes over time.
Nitrogen levels start out low and increase because of symbiotic nitrogen-fixing bacteria in alder.
Then other trees can survive.

56. Succession Models Inhibition Model Tolerance Model
Colonists hold onto their space and inhibit growth of other plants until the colonists are damaged or die.
Tolerance Model
Different types of plants can colonize an area at the same time.
Chance determine which seeds arrive first.

57. Ecological succession: Primary succession
pioneering plant species are next
retreating glaciers leave moraines. autotrophic bacteria are first colonizers.
mosses and lichens are first macroscopic autotrophs. soil forms gradually

58. Succession continues until a climax community is formed.
spruce replace alder and cottonwood
final stage is a spruce and hemlock forest

59. Secondary succession occurs after disturbance that leaves the soil intact. Other examples?
Fig – 1988 fires in Yellowstone

60. Community Diversity
Community stability can be recognized in three ways.
Persistence through time.
Resistance to change.
Recovery once a disturbance has occurred.

61. Intermediate Disturbance Hypothesis
Moderate amounts of disturbances at moderate frequency are required for a high degree of community diversity.
If widespread disturbances occur frequently, diversity will be limited.

62. Intermediate Disturbance Hypothesis

63. Predation, Competition, and Biodiversity
In certain communities, predation by a particular species reduces competition and increases diversity.
Predators that regulate competition and maintain community diversity are referred to as keystone predators.
Introduction of exotic species into a new area may lead to unbridled competition and resultant reduction in biodiversity.

64. Predation, Competition, and Biodiversity
In certain communities, predation by a particular species reduces competition and increases diversity.
Predators that regulate competition and maintain community diversity are referred to as keystone predators.
Introduction of exotic species into a new area may lead to unbridled competition and resultant reduction in biodiversity.

65. Review Diversity and Composition Models Island Biogeography
Habitat and Ecological Niche
Competition Between Populations
Predator-Prey Interactions
Symbiotic Relationships
Community Development
Community Diversity