Community Ecology

Community

Group of individuals from different species in a given area

Species Richness

Relative abundance

Shannon Index

Calculates the diversity of the community

H=-(pAlnpA + pBlnpB + pClnpC+…)

Higher-Diversity Communities

More productive

More resistant to invasive species

Quagga and Zebra Mussels

Artichoke Thistle

ESS

Interspecific Interactions

Interaction Ind. # 1 Ind. # 2

Competition - -

Predation + -

Mutualism + +

Commensalism + 0

Competition

Interspecific

Intraspecific

Competitive Exclusion Rule

Two species cannot occupy the same ecological niche

Resource Partitioning

Character Displacement

Predation

Plant Defenses

PhysicalThorns

Spines

ChemicalPoisons

• Nicotine

• Strychnine

• Morphine

• Tannins

Animal Defenses

PhysicalShells

Horns/Antlers/Quills

Teeth

ChemicalPoisons

Odors

Animal Defenses

Cryptic Coloration

Aposematic Coloration

Animal DefensesBatesian Mimicry

Mullerian Mimicry

Animal Defenses

Mutualism

Commensalism

Trophic Levels

Primary Producers

Primary Consumers

Secondary Consumers

Tertiary Consumers

Quaternary Consumers

Trophic Levels

Primary Producers

Primary Consumers

Secondary Consumers

Tertiary Consumers

Quaternary Consumers

Keystone Species

Keystone Species

Top-Down Model

Predation controls community organization

Also called the trophic cascade model.

Keystone Species

Bottom-Up Model

Suggests direction influence from the lowest trophic levels

Control by the absence or presence of micronutrients which controls plant communities

Adding more nutrients = more biomass