4 ways organisms interact

• competition

  • compete for available resources (food, mating partners, etc.)

  • occurs between both the same and different kinds of organisms

• predation

  • hunt and kill other organisms to supply their energy needs

  • occurs between different kinds of organisms,

• cooperation

  • live together and help each other

  • occurs between the same kind of organisms

  • ex) herds, packs, colonies, families, etc.

• symbiosis

  • live in close association with another kind of organism

  • occurs between different kinds of organisms,

resource

• anything needed by an organism for life

• ex) nutrients, water, light, space

limiting factor

• a nutrient in short supply or one that cycles slowly

• this LIMITS the growth of the population

symbiosis

• mutualism

  • a relationship where both organisms benefits

  • ex) insects transfer pollen between plants as they gather nectar for food

• commensalism

  • a relationship where one organism benefits; the other is neither harmed nor helped

  • hermit crabs make homes in shells abandoned by snails

• parasitism

  • a relationship where one organism benefits; and the other is harmed in some way

  • ex) ticks feed on dog’s blood

feedback

• any process that increases or decreases a change to the system

feedback loop

• a feedback process where an output of matter, energy, or information is fed back into the system as an input and leads to changes in that system

positive feedback loop

• causes systems to change further in the same direction

• increases change to a system

• ex) melting of a polar ice cap, increased erosion due to decreasing vegetation

negative feedback loop

• causes systems to change in the opposite direction

• decreases change to a system

• ex) reproduction, overgrazing, less reproduction