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Aim:Aim: How does competition How does competition affect organisms in nature?affect organisms in nature?

Do Now:Do Now: List three things you List three things you compete for in your life. compete for in your life.

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II. Predator-Prey II. Predator-Prey RelationshipsRelationshipsA. Predators help control the size of the prey

populations

1. Prey populations are kept below their carrying capacity (The max. number an ecosystem can support).

Example: NYS Deer.

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II. Predator-Prey II. Predator-Prey RelationshipsRelationshipsB. B. Population explosions are common when prey

populations are moved into areas that don’t have natural predators.

Ex - Rabbits in Australia

• 1859 - one dozen rabbits were introduced

• 1865 - 20,000 rabbits were shot

• 1887 - 20,000,000 rabbits were shot

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II. Predator-Prey II. Predator-Prey RelationshipsRelationships

C. Prey populations control the size of the predator populations

1. When a predator has one type of food, it depends on how many prey there are.

ex. Lynx and Snowshoe hairs

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II. Predator-Prey II. Predator-Prey RelationshipsRelationships

D. Neither predator nor prey influences the other’s population size.

1. This occurs when a predator relies on many different prey species for food.

Example: Humans

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Objective: Population SizeObjective: Population Size

Do NowDo Now: :

• Take out your HW to be Take out your HW to be checked.checked.

• Why is the interaction on the Why is the interaction on the next slide taking place, and next slide taking place, and predict what will happen next.predict what will happen next.

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Zebra MusselsZebra Mussels

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III. Food Chains – show what III. Food Chains – show what things eat.things eat.

A.A. Parts of the food chain: Parts of the food chain: 1.1. Producers – make their own food.Producers – make their own food.

2.2. Herbivores – eat plants only Herbivores – eat plants only

3.3. Carnivores –eat animals onlyCarnivores –eat animals only

4.4. Omnivore – eat plants or animalsOmnivore – eat plants or animals

5.5. Decomposers – break down dead Decomposers – break down dead organisms back to soil.organisms back to soil.

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Food ChainFood Chain

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III. Food ChainIII. Food Chain

B. Food Web – shows overlapping food B. Food Web – shows overlapping food chain.chain.

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Food WebFood Web