1. Creative Community Ecology
Ch 54 notes

2. I. Introductory Vocabulary
Community
group of populations in an area or habitat

3. II. Interspecific Interactions
Relationships between the species of a community
Types include:
Competition
-/-
Predation
+/-
Mutualism
+/+
Commensalism
+/0

4. A. Competition Detrimental to both species
Organisms compete for available resources such as food, water, shelter, sunlight

5. 1. Competitive exclusion principle
Two species so similar that they compete for the same limiting resource cannot coexist in the same place

6. 2. Ecological niche
sum total of a species’ use of biotic and abiotic resources – how an organism fits into it’s ecosystems (it’s role)
two species cannot coexist in a community if they occupy the same niche

8. 3. Resource partitioning
if two species have the same niche, the less competitive one will either be driven from the area, or will evolve through natural selection to use a different set of resources

9. 4. Character displacement
The tendency for characteristics to be more divergent in sympatric (geographically overlapping) populations of two species than in allopatric (geographically separate) populations of the same two species

10. B. Predation beneficial to one organism but not the other
one organism eats another
includes herbivory (eating part of a plant), parasitism (parasite living on host)

11. 1. Predator adaptations acute senses to locate prey
many have claws, teeth, fangs, stingers, poison
generally fast and agile if they have to pursue prey

12. 2. Animal defenses against predators
Passive defenses: hiding, chemical toxins
Active defenses: escaping, defending themselves, warning calls

13. Animal defenses against predators
Adaptive coloration
camoflauge – cryptic coloration to blend with environment
aposematic coloration – bright coloration of animals that have chemical toxins dangerous to predators
Can you see me?

14. Animal defenses against predators
Mimicry – “copycat” adaptation
Batesian mimicry – harmless species mimics a harmful model (ex. larvae puffs up and resembles cobra)
I’m Harmless!!!

15. Animal defenses against predators
Mullerian mimicry two unpalatable species resemble each other
predators learn more quickly about danger of the appearance

16. 3. Parasites and Pathogens as predators
host harmed in the process
endoparasites – live within their
host (tapeworm)
ectoparasites – feed on external
surface of host (mosquito)
parasitoidism – insects lay eggs
on living host

17. 4. Herbivory Organism eats part of a plant or alga
ex. Cattle, many invertebrates, manatee
Herbivores may have adaptations such as chemical sensors to detect toxins, specialized teeth

18. 5. Plant defenses against herbivores
Chemical toxins
Spines
Thorns
Used since plants cannot run from predator

19. C. Mutualism
interspecific interaction that is beneficial to both species
often requires coevolution of adaptations in both species
if one is harmed, the other is usually harmed as well

20. There’s bacteria in my belly
Examples of Mutualism
microorganisms in digestive system of termites and ruminants (help digest cellulose)
Photosynthesis by algae in tissue of coral
There’s bacteria in my belly
Who knew!!!

21. 4. Commensalism
interaction between species that benefits only one of the species but no harm to the other
ex. algae growing on shell, birds eating insects flushed up by cows
Yummy Bugs
MOOOO

22. III. Biodiversity
Species diversity in a community

23. Species Diversity
The variety of different kinds of organisms that make up the community

24. Species Diversity Species Richness Relative Abundance
number of species that a community can contain
Relative Abundance
The proportion of each species represents of all individuals in the community

25. Which community is more diverse???

26. Community 1 and 2 are equal in their species richness (both have 4 different species)
Community 1 is more diverse because there is equal representation of all 4
Community 2 has a large amount of Species A
Community 1 has greatest heterogeneity (looks at species number and relative abundance

27. IV. Trophic structures
feeding relationships between organisms

28. A. Food Chain
Transfer of food energy from it’s source in plants through herbivores to carnivores and eventually to decomposers
Each link makes a trophic level
Each food chain has only four or five links due to inefficient energy transfer as you move up the chain
Longer food chains may not be able to recover as quickly from environmental change

30. B. Food Web
more than one food chain hooked together

31. Dominant species have the highest abundance or the highest biomass
exert control over occurrence and distribution of other species

32. Keystone species
exert control on community structure by their ecological role (niche)
may help to maintain diversity and balance in community
ex. sea otter eats sea urchin eats algae
remove sea otter (keystone) and algae population goes down
add sea otter – algae population increases

33. Example of Keystone Species
Removal experiment
Robert Paine and Sea Star – Pisaster is a keystone predator of mussels
With Pisaster – many species able to coexist
Without Pisaster – mussels able to overtake area eliminating many other species

35. Foundation Species
Exert influence on a community by causing physical changes in the environment
ex. Beaver building a dam can transform the landscape on both sides
Can be positive or negative on other species

36. V. Disturbances
storms, fires, floods, drought, overgrazing, human activities
may upset balance or equilibrium in community

37. Ecological succession
transition in the biological species composition of a community usually following a disturbance

38. Primary succession
succession that begins in a virtually lifeless area where soil has not yet formed (like Hawaii)
Autotropic bacteria  lichens/mosses soilother plants animals

39. Secondary succession
existing community has been cleared by a disturbance that leaves soil intact
Often these areas return to something like the original state