Interdependence and interactions in an ecosystem

Interpret interactions among organisms exhibiting predation, parasitism, commensalism and mutualism

Identify and illustrate that long-term survival of a species is dependent on a resource

Investigate and explain the interactions in an ecosystem including food chains, food webs and food pyramids

Biotic factors: living parts of the ecosystem (ex: trees, birds, etc.)

Abiotic factors: non-living parts of the ecosystem (ex: rocks, water, etc.)

Population Community Ecosystem

Population: group of organisms of the same species living together

Community: groups of populations living in the same area

Ecosystems: community + all the non-living surroundings

Name the

Biome

DesertTemperate Forest

Tundra

TiagaTropical Rainforest

Grasslands

Predator Prey Predators feed on other organisms. Prey are the organisms that get eaten. The prey population needs to be larger

than the predator population. As the prey population increases, the predator population increases. If the prey population decreases, the predator population decreases.

Predation keeps population size within the limits of available resources.

Symbiosis: means “living together”--there are 3 types of symbiotic relationships

Parasitism: the host is harmed and the parasite benefits (ex: human and a tapeworm)

Commensalism: one organism is not harmed nor benefited and the other organism benefits (ex: tree and a bird)

Mutualism: both organisms benefit (ex: clown fish and an anemone)

Symbiosis

Host Parasite

Organism Unaffected Organism Benefited

Organism Benefited Organism Benefited

Food Chain Food Chain: represents the flow of energy in an

ecosystem; the arrows represent the direction of energy flow and are called trophic levels. There are usually 3-4 trophic levels in a food chain but no more than 5 levels

Grass Insect Bird Hawk (plant) (herbivore) (carnivore) (carnivore)

Producer: organisms that undergo photosynthesis (grass); also called autotrophs

Consumer: organisms that must eat producers/consumers; also called heterotrophs

Primary consumer: these organisms eat the producers (insects)

Secondary consumer: these organisms eat the primary consumers (bird)

Tertiary consumer: these organisms eat the secondary consumers (hawk)

Food Chain Cont. Scavengers: organisms that feed on dead

animals (ex: vultures) Decomposers: organisms that break

down dead organic material (ex: fungi) Herbivores: eat only producers Carnivores: eat only consumers Omnivores: eat producers and

consumers

Food Webs Food Webs: are interconnected food chains

Food chain 1: seeds chipmunk grizzly bear Food chain 2: berries chipmunk goshawk

Pyramids

Grasses100%

Grasshoppers10%

Birds 1%

Fox0.1%

Birds10 kg

Fox1 kg

Grasshoppers100 kg

Grasses1000 kg

Energy Pyramid Number Pyramid Biomass Pyramid

There must always be more prey than predators because the predators can not use all the energy that is consumed from the prey. The lower an organism is on the food chain, the higher the numbers of these organisms. The more organisms there are at a trophic level, the more mass the group of organisms has.

Biological Magnification

If a chemical or toxin (ex: DDT) enters the food chain at a low level (ex: grass) the amount of that chemical increases as you move up the food chain.