COMMUNITY ECOLOGY

What is a community? Many species living closely together, so that they interact with each other. What is a species?

Interspecific Interactions Interaction between 2 or more species that use the same resource Competition must occur: interference competition - actual fighting occurs interspecific competition - consumption or use of similar resource

Competitive Exclusion Principle

What is meant by an ecological niche?

Fundamental / Realized Niches

Resource Partitioning of Lizards

Character Displacement Among the Galapagos Finches

Symbiosis Close association between two species

Clownfish Among Sea Anemone’s Tentacles

Cleaning Symbiosis

Mutualism Between Ants and Acacia Tree

Commensalism Between Ox Peckers and Cape Buffalo

Commensalism

Parasitism

Camouflage in the Anglerfish

Anti-predator Defenses Swallowtail Butterfly Larva Anti-predator Defenses South American Lantern Fly

Batesian Mimicry Hawk Moth Larva Green Parrot Snake

Müllerian mimicry: Cuckoo bee (left), yellow jacket (right)

Mimicry Among Insects Batesian (a, b, c); Mullerian (d, e) Flower Fly Longhorn Beetle Moth Yellowjacket Bumblebee

Aposematic Coloration

Nudibranch

Chemical Defense and Aposematic coloration are seen here:

Cryptic coloration is seen here

Deceptive Coloration: Moth with “Eyeballs"

Parasites are also +/- Symbiotic Interaction Endoparasites Ectoparasites Parasitoids - insects (usually wasps) that lay eggs on other insects and larvae feed on the host.

Plant Defenses Against Predators: What defense is seen here? Other Defenses: Chemicals that cause plant to taste bad

Interspecific Interactions: What is coevolution?

What factors will be the most significant in determining the structure of a community?

Species Diversity Combination of two factors: 1) Richness - number of different species 2) Relative Abundance - number of individuals in each species

Trophic Structure The different feeding relationships between organisms According to the “rules of ten,” approximately 10% of the potential energy stored in the bonds of organic molecules at one trophic level fuels the growth and development of organisms at the next trophic level.

Trophic Structure Five examples: 1. Primary Producers 2. Primary Consumers 3. Secondary Consumers 4. Tertiary Consumers 5. Decomposers and Detrivores

Primary Producers: grass (10,000 KCAL) Trophic Structure Tertiary Consumer: snake (10 KCAL) Secondary Consumer: mouse (100 KCAL) Primary Consumer: grasshopper (1,000 KCAL) Primary Producers: grass (10,000 KCAL)

Species with a Large Impact Dominant Species Keystone Species

Keystone Species

Sea Otters as Keystone Predators

Disturbances Influence Species Diversity and Composition Ex: Succession – predictable changes that occur in community over time

primary succession - soil never formed before secondary succession - existing community was disturbed and returned to original state.

Lichens Moss These are classic pioneer species.

Lichens

Moss With Sporophytes Gametophytes

Large-scale Disturbance: Eruption of Mount St. Helens

Patchiness and Recovery Following a Large-Scale Disturbance

Secondary Succession Eventually a climax community usually results.

Community that remains essentially the same over long periods of time. Climax Community Community that remains essentially the same over long periods of time. It is the final stage of ecological succession.

Name the three types of symbiotic relationships.