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.)  + 

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.  + unaffected

Symbiosis – Commensalism Examples

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

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+

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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?