Relationships between organisms

Connections between organisms• All living things on the earth

are connected in some way.• This unit we will study these

relationships:– Producer/consumer/decomposer– Predator/Prey– Competition– Symbiosis

Producer/consumer/decomposer

• We’ve already learned that a producer is able to use the sun’s energy to make food.

• We’ve also learned that a consumer has to get food by eating producers (herbivore) or other consumers (carnivore) or both, (omnivore).

Producer/consumer/decomposer

• Producers (autotrophs) capture the energy that all other organisms rely on to survive.

• Without producers, the sun’s energy couldn’t be used by living things.

Producer/consumer/decomposer

• A decomposer is an organism that breaks down waste and dead organisms.

• Decomposers help to recycle nutrients.

• Without decomposers, dead things would pile up, and nutrients would run out.

Producer/consumer/decomposer

• Are each of these organisms a producer, consumer, or decomposer?

Consumers - Predator/Prey

• An organism that kills and eats another organism for food is called a predator.

• An organism that gets killed and eaten by a predator is called the prey.

Predator/Prey

• Predator populations rise and fall in relation to the prey they eat.– (If there is a decrease in

the amount of prey, there will soon be a decrease in the amount of predators).

– (If there is an increase in the amount of prey, there will soon be an increase in the amount of predators).

Predator/Prey

• Example: Voles vs. Birds of Prey in Cache Valley – Christmas Bird Count

2011– Wet Spring led to record

low number of voles– Fewer birds of prey

reported that Christmas.

Competition

• Competition occurs when 2 or more organisms are both trying to use the same limited resource.

Competition

• Competition could occur between producers or consumers

• Competition might occur between organisms of the same species, or different species.

Competition

• Competition might occur because of limited:– Food– Space– Sunlight– Mates– Or any other limited

resource

Carrying capacity

• The maximum amount of individuals of a certain species that an environment can support is called the carrying capacity.

Carrying capacity

• Example: Eurasian Collared Doves in Cache Valley

Limiting factor

• The resource that runs out when a population reaches its carrying capacity is called the limiting factor.

• Limiting factors lead to competition between organisms.

Symbiosis• Symbiosis is when two

different species of organisms live closely together for an extended period of time.– “Sym” = same– “bio” = life

• There are 3 types of symbiosis:– Mutualism– Commensalism– Parasitism

Symbiosis - Mutualism

• Mutualism is when the 2 organisms both benefit from the relationship. (They help each other.)

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Symbiosis – Mutualism - Examples

Symbiosis - Commensalism

• Commensalism is when one of the organisms benefits from the relationship, and the other is not helped or harmed by it.

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Symbiosis – Commensalism - Examples

Symbiosis - Parasitism

• Parasitism is when one organism benefits from the relationship, and the other organism is harmed.

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Symbiosis – Parasitism - examples

Symbiosis - ?

• Why don’t we have a word for a relationship where both organisms are harmed by the relationship?

Symbiosis and you

• What is one example of mutualism that a person might be involved in?

• What is one example of commensalism that a person might be involved in?

• What is one example of parasitism that a person might be involved in?

Symbiosis and you

• Think about your friends.– What would a mutualist

friend be like?– What would a

commensalist friend be like?

– What would a parasitic friend be like?

– What type of friend are you?