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.
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 - Commensalism
• Commensalism is when one of the organisms benefits from the relationship, and the other is not helped or harmed by it.
• + unaffected
Symbiosis - Parasitism
• Parasitism is when one organism benefits from the relationship, and the other organism is harmed.
• +
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?