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Cooperative Existence

Description:

If one population depends on another one and vice-versa, we speak about cooperative existence or collaboration. Both populations grow until they reach a steady state, which depends on the growth and mortality rate of both populations.

Examples:

  • A small fish that lives as a parasite on a bigger fish cleaning its skin
  • A fungus and algal cells that form together the flowerless plant lichen
    		•  Diagram

    Variables:

    Q1, Q2 = Populations 1 and 2
    R = growth factor
    K1-8 = increasing and decreasing factors

    Equations:

    R=1/(1+K1*Q1*Q2-K2*Q1*Q2)
    DQ1=K5*R*Q1*Q2-K7*Q1*Q2-K3*Q1
    DQ2=K6*R*Q1*Q2-K8*Q1*Q2-K4*Q2

    Simulation:

    The graph shows the changes of Q1 (green) and Q2 (red) over a time period.
    Source code: Coop.java

    "What if" Experiments:

  • If one of the two species started with a much higher inicial population, how would it affect the level of the steady state
  • How do the growth and mortality rates of one population affect the level of the steady state
    		•