1. Chapter 54
Community Ecology

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

3. Interspecific Interactions
Interaction between species.
May be positive, negative, or neutral (in regards to fitness)
Ex:
Predation
Mimicry
Competition
Symbiosis

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

5. Herbivory (+/-) When an organism eats parts of a plant or algae.
Herbivore – may have special adaptations to find their prey.
Plants – may have adaptations to avoid being eaten.

6. Predation/Herbivory
Often results in interesting defenses or adaptations.
Ex:
Cryptic coloration
Aposematic coloration

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

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

15. Mimicry
Defense mechanism where the mimic has a resemblance to another species, the model.
Types:
Batesian
Müllerian

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

17. Müllerian Mimicry Two unpalatable species resemble each other.
Yellow Jacket
Cuckoo Bee

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

19. Competitive Exclusion Principle
Predicts that two species with the same exact requirement cannot co-exist in the same community.
The better adapted species will survive and the less adapted will go extinct.

20. Think, Pair, Share
Discuss if the Competitive Exclusion Principle explain the spacing of fast food restaurants on the “strip” in most towns.

21. Ecological Niche
The sum of a species’ use of the biotic and abiotic resources in its environment is called the species’ ecological niche.
How a species “makes its living” in its ecosystem.
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. Think, Pair, Share
Again in terms of fast food restaurants, explain the concept of a fundamental vs. realized niche.

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

26. A. distichus
A. insolitus

27. 7 species live in close proximity, all feed on insects, but since they each perch in a different area, their niches overlap less (resource partitioning)

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

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

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

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

33. Species with large impacts
Some species have larger impacts on a community structure than others.
Ex:
Dominant Species
Keystone Species
Foundation Species

34. Dominant Species
A species that is the most abundant or has the highest biomass in a community.
Has a major effect on a community both biotically and abiotically.

35. Reason for Dominance? Best Competitor?
Best in avoiding predators and disease?
Invasive species may fit the last explanation.

36. Example Chestnuts – used to make up to 40% of the forest.
Lost between because of fungus disease.
Major impact on wood and nut industries.

37. Response Some tree species increased in abundance to fill the gap.
Mammals and birds did OK.
7 species of insects went extinct.

38. Keystone Species
Not a dominant species, but has a major impact in the community structure.
Often a top predator that controls the numbers of other species.
Ex. Sea Otters

40. Foundation Species
Species that cause physical changes in the environment that affect others.
Ex. Beavers, Bison, Black Rush

42.
How wolves change rivers

43. Succession
Changes in species composition over time.

45. Succession Stages
Climax Community - An ecological community in which populations of plants or animals remain stable and exist in balance  with each other and their environment.

46. Succession Types
1. Primary 2. Secondary

47. Primary Succession
Succession with only abiotic materials as the starting substrate
Ex: volcanic islands glaciated areas road cuts

48. Secondary Succession
Succession with biotic materials (living or dead) as the starting substrate
Ex:
Cutting down a forest
Forest fire
Tornado/storm damage

49. Steps of Succession
Pioneer Species – the first organisms to appear in the area in primary succession
Usually moss or lichens

50. What do Pioneer Species Change?
Enrich the soil – as generations die, their remains decompose and add nutrients to the soil (often N).
The soil is now able to support a greater variety of species such as grasses and small shrubs.

51. Which occurs faster, primary or secondary succession?
What can you do to speed up succession?

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

53. Some points about Succession
The Organisms are changing in the area over time. General pattern is an increase in biodiversity.
The Climate of the area is NOT changing over time.

54. Other Changes
Soil – becomes richer in N, more depth, better water retention etc.
Light – can decrease at ground level because of shading by taller plants.

55. Summary Know the various types of interspecific interactions.
Know the Competitive Exclusion Principle and Niche Concept.
Know Species with large impacts.

56. Summary
Know some examples and causes of succession.