Community Interactions

EQ: How do the three types of symbiosis differ?

Types of Interactions

CompetitionPredationSymbiosis

MutualismCommensalismParasitism

Competition (-/-)Organisms of the

same or different species attempt to use the same ecological resource in the same place at the same time Bison

Elk Herd

Moose

Competition

Interspecific competition: Competition between members of different species

Intraspecific competition: Competition among members of the same species

Blue Butterfly

Tiger Swallowtail butterfly

Competitive exclusion principle:

No two species can occupy exactly the same niche in exactly the same habitat at exactly the same time.

One will always exclude the other

Predation (+/-)

Herbivory:

• Type of predation

• Interaction in which an herbivore feeds on producers.

predator

prey

Falcon

Ground Squirrel

Interaction in which one organism captures and feeds

on another organism

PredationKeystone species: a single species that is vital to the ecosystem stability.

Ex. Otters/kelp/sea urchins

Predation

Rabbit and Coyote

rabbitcoyote

Arctic Hare

Coyote

Symbiosis

Any relationship in which two species live closely together is called symbiosis (“living together”)

MutualismCommensalismParasitism

Mutualism (+/+)

Both organisms benefit

o Examples:

o Flowers and insects

o Ants and aphids

Bee on Purple Flower

Ant and Aphid

Mutualism (+/+)Lichen

Algae and fungus living together

Lichen

Commensalism (+/0)One member of the

association benefits and the other is neither helped nor harmed.

Spanish Moss

Commensalism (+/0)

Whales & Barnacles

Barnacles on Whale

Commensalism (+/0)

Epiphytes

“air plants”

EpiphyteEpiphyte in Tree

Parasitism (+/-)

Ticks

The parasite obtains all or part of its nutritional needs from the other organism, the host.

Blacklegged Tick: An adult female blacklegged tick, engorged after a

blood meal, rests on a leaf.

BeforeAfter

Black Legged Tick

Parasitism (+/-)

One benefits; one harmed

Examples: tapeworms inside mammals; fleas, ticks, and lice on mammals

Female Head Lice