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The POPULUS modelling software

The POPULUS modelling software Download your copy from the following website (the authors of the program are also cited there). This primer is best used with a running POPULUS program. http://www.cbs.umn.edu/populus/ The opening screen is shown below (this primer is based on Java Version 5.4).

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The POPULUS modelling software

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  1. The POPULUS modelling software Download your copy from the following website (the authors of the program are also cited there). This primer is best used with a running POPULUS program. http://www.cbs.umn.edu/populus/ The opening screen is shown below (this primer is based on Java Version 5.4) Main Menu bar – gives access to major program features

  2. The POPULUS modelling software Depending on your screen size, you may need to adjust the POPULUS program windows. Each of them can be scaled by clicking-and-dragging on any edge (just like any other window). POPULUS windows may be repositioned by clicking-and-dragging on their heading. POPULUS windows may be scaled by clicking-and-dragging on any edge.

  3. The POPULUS modelling software A Help document can be accessed by clicking on the Help button in the menu bar. The help document is a pdf file and will require a pdf reader.

  4. The POPULUS modelling software Access the models by clicking on the Model button. We’ll discuss Lotka-Volterra competition models in this section. • NOTE: This primer assumes that you have mastered the lesson(s) on: • Density-Independent growth models • Density-Dependent growth models • Lotka-Volterra competition (co-existence) • Lotka-Volterra competition (either species may win)

  5. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) We have seen from the previous models the scenarios of co-existence and of either species winning. These are situations in which both species are equally competitive and so both have a chance of winning. In the co-existence model, the species are not aggressive, hence they don’t bring the other to extinction. In the second model, however, the species are equally competitive and aggressive so that co-existence is not possible. The outcome, in this case, is dependent on the initial abundance of the competing populations.

  6. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) In this primer, we will look at the scenario in which one species is so much better than the other that its victory is inevitable regardless of initial abundance. Sounds unrealistic? Well, this often happens in the wild with introduced species (also known as exotics). Even if just a few individuals are introduced, they can easily overcome native species and wipe them out. Input the following parameters and let’s get cracking at the model. (Activate the N2vs N1plot).

  7. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) K1 = 300; K2 = 300

  8. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) K1 = 300; K2 = 500

  9. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) K1 = 300; K2 = 700

  10. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) K1 = 300; K2 = 900 What we’ve done is to give Species 2 an advantage by increasing its K2. To make it an even stronger competitor, let’s increase competition coefficient α (the effect of Species2 on Species 1). Let’s see this in the following graphs.

  11. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) (K1 = 300; K2 = 900) α = 0.3;β = 0.2 Right away, it becomes evident that increasing the alpha (α) results to an even stronger Species 2. This is seen in the graph as a decrease in the area where Species1 grows better than Species2 (see encircled area).

  12. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) (K1 = 300; K2 = 900) α = 0.3;β = 0.2 Here, we have a completely dominant Species 2. There is no area where Species 1 grows better than Species2, hence the extinction of Species1 is inevitable even if you start with 1,000 individuals of Species 1 and just 5 of Species 2.

  13. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time) Let’s look at various scenarious in which the same species wins all the time. Input the parameters shown in your model and see if you can come up with your own combinations.

  14. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time)

  15. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time)

  16. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time)

  17. The POPULUS modelling software: Lotka-Volterra Competition (same species wins every time)

  18. The POPULUS modelling software: Lotka-Volterra Competition We end our discussion of the Lotka-Volterra Competition models where the same species always wins. With this, we end our Lotka-Volterra models on competition between two species.

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