1. Community Ecology
Chapter 54

2. Community Interspecific interactions
Interactions with different species
Competition
Predation
Herbivory
Symbiosis

3. Interspecific Competition
Two species compete for resources
Competitive exclusion:
One species utilizes resources more efficiently
Eliminates the other

4. Paramecium

5. Niche Species use of resources in its environment Abiotic & biotic
Fundamental niche:
Area that a species is capable of utilizing
Realized niche:
Actual resources the species utilizes

6. Resource Partitioning
Species use similar niches
Subdivide available resources
Warbles (small bird)-spruce trees
Lizards in Dominican republic
Character displacement:
Sympatric species diverge more than allopatric species

7. Barnacles

8. Resource partitioning

9. Predation
Consuming of one organism by another

10. Predators

11. Animal defenses Hide or run
Chemicals (bees, wasps, scorpions, spiders)
Snakes, lizards, frogs
Coloration
Aposematic: warning
Cryptic: blending

12. Aposematic

13. Cryptic

14. Animal defenses Mimicry Batesian:
Harmless animals mimic harmful animals
Mullerian:
Several harmful animals look the same (safety in numbers)

15. Batesian mimicry

16. Mullerian mimicry

17. (a) Mechanical defense (b) Chemical defense
▶ Porcupine
▶ Skunk
(c) Aposematic coloration:
warning coloration
(d) Cryptic coloration: camouflage
◀ Poison dart frog
▶ Canyon tree frog
(e) Batesian mimicry: A harmless species mimics a harmful one.
(f) Müllerian mimicry: Two unpalatable species mimic each other.
Figure 54.5 Examples of defensive adaptations in animals
▲ Venomous green parrot snake
◀ Yellow jacket
◀ Nonvenomous hawkmoth larva
◀ Cuckoo bee

18. (a) Mimicking a sea snake
Mimic octpus
(a) Mimicking a sea snake
(b) Mimicking a flounder
Figure 54.6 The mimic octopus
(c) Mimicking a stingray

19. Herbivory Organism eats part of a plant Thorns, spines, prickles
Chemicals
Mustard oils, milkweed, nicotine

20. herbivore
Figure 54.7 A West Indian manatee (Trichechus manatus) in Florida

21. Symbiosis 2 or more organisms interact in a permanent relationship
Lichen
Mycorrhizae
Types of symbiosis
Commensalism
Mutualism
Parasitism

22. Commensalism Interaction benefits one organism
But neither harms nor helps the other
Fish & sea anemones
Egrets & cattle

23. Commensalism

24. Commensalism

25. commensalism
Figure 54.9 A possible example of commensalism between cattle egrets and African buffalo

26. Mutualism Interactions benefit both species
Flowers and bees, birds or bats
Ants and acacias (plant)

27. Mutualism

28. mutualism
Figure 54.UN08 Test your understanding, question 14 (interspecific interactions)

29. Mutualism

30. Parasitism One organism benefits at the cost of its host organism
Parasite is usually smaller than host
Ectoparasites (external)
Ticks. lice
Endoparasites (internal)
Tapeworms

31. Parasitism

32. Community structure
How these interspecific interactions work all together
1. Predation reduces competition
2. Parasitism vs competition
3. Indirect effects (rodents and ants)
4. Keystone species
Species that has a strong effect on the composition of a community

33. Keystone species

34. Succession Communities change from simple to complex over time
Secondary succession:
New community arises where an old community was disturbed
Primary succession:
New community arises on bare lifeless substrate (glacier receding)

35. Primary succession

36. Secondary succession