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Interdependence and interactions in an ecosystem.

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Presentation on theme: "Interdependence and interactions in an ecosystem."— Presentation transcript:

1 Interdependence and interactions in an ecosystem

2 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

3 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

4 Name the Biome Desert Temperate Forest Tundra Tiaga Tropical Rainforest Grasslands

5 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.

6 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

7 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)

8 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

9 Food Webs Food Webs: are interconnected food chains Food chain 1: seeds  chipmunk  grizzly bear Food chain 2: berries  chipmunk  goshawk

10 Pyramids Grasses 100% Grasshoppers 10% Birds 1% Fox 0.1% Birds 10 kg Fox 1 kg Grasshoppers 100 kg Grasses 1000 kg Energy PyramidNumber PyramidBiomass 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.

11 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.


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