1. Ecology: Communities

2. Organizational Hierarchy of Life
Most Complex
Least Complex
biosphere
ecosystem
community
population
organism
organ system
organ
Living
tissue
cell
organelle
macromolecule
Non-living
molecule
atom
sub-atomic particles

3. Term Definition Population Community Ecosystem Biosphere
Individuals of one species that occupy a given environment
Community
All populations in a common environment
Ecosystem
Organisms in community plus nonliving factors
Biosphere
Zones of air, land and water at earth’s surface occupied by living things

5. Interactions in Communities
-Competition
-Predation
-Symbiosis

6. Competition Relates to Niche Overlap
Degree of competition is proportional to the overlap in ecological niches of competing species
Ecological niche = total way of life of all members of a species
--Habitat
--Physiological needs such as temperature, moisture, nutrients
--Behavior --Interactions with other species

7. Outcomes of Competition Competitive Exclusion = One species eliminates the other
Grown in Separate Flasks
Grown in the Same Flask

8. Outcomes of Competition Resource Partitioning: Use of small differences in environment to fulfill needs
Figure: 39.2
Title:
Resource partitioning
Caption:
Each of these five insect-eating species of North American warblers searches for food in different regions of spruce trees.

9. Outcomes of Competition Character Displacement: Through natural selection, two species diverge in characteristics that overlap

10. Theoretical vs. Actual Niche
Theoretical Niche
Defined by Physiological Limits: needs for food, water, temperature
Actual Niche
Portion of Theoretical Niche that is used, limited by competition

11. Competition Between Two Species of Barnacles for Region Near the Ocean Surface
Barnacle C, theoretical niche
Barnacle C,
Actual niche
theoretical and
Barnacle B,
actual niche

12. Applying Your Knowledge
Character Displacement
Competitive Exclusion
Resource Partitioning
Which one involves the use of different features of the environment so that two species can coexist in the same area?
Which one involves physical changes in two separate species?
Which one involves the elimination of one of the competing species?

13. Effects of Predation Predation = eating of live organisms
Eliminates old and weak individuals
Regulates numbers of both predators and prey
Coevolution of predator and prey
Regulates diversity of populations in community
“A keystone species plays a major role in determining community structure, one that is out of proportion to its abundance in the community. Removal of the keystone species dramatically alters the community.”
When Pisaster present, 15 species can be sustained, including mussels, limpets, barnacles, chitons. Only 8 species remain after removing Pisaster, mussels (favorite food of Pisaster) and barnacles predominate. “Mussels outcompeted algae and other invertebrates.”
The sea star Pisaster is a keystone species in aquatic communities in the Pacific Northwest.

14. Population Cycles in Predators and Prey
Figure: 38.E1
Title:
Population cycles in predators and prey
Caption:
Snowshoe hares and their lynx predators are graphed on the basis of the number of pelts received by the Hudson Bay Company.

15. Coevolution of Predator and Prey
Camouflage hides prey

16. Symbiosis Close Interaction Between Species
Parasitism
One helped , other harmed

17. Symbiosis
Mutualism
Both helped

18. Symbiosis
Commensalism
One helped, other neither helped nor harmed

19. Applying Your Knowledge
Mutualism
Commensalism
Parasitism
Which type of symbiosis is operative if
A barnacle attaches to a whale so it can feed on organisms encountered as the whale swims but the whale is unaffected by the barnacle?
Athlete’s foot fungus starts growing between your toes?

20. Will the Monarch Butterfly be affected by the development of herbicide resistant crops?