Wolf Sheep Predation (System Dynamics)

1 collaborator

Uri Wilensky (Author)

WHAT IS IT?

This is a model of a simple predator-prey ecosystem. It uses the System Dynamics Modeler to implement the Lotka-Volterra equations.

The Lotka-Volterra equations are a pair of first order, non-linear, differential equations that describe the dynamics of biological systems in which two species interact.

HOW IT WORKS

At each step, the value of the SHEEP-BIRTHS flow is added to SHEEP stock, and the value of the SHEEP-DEATHS flow is subtracted from the SHEEP stock. The same is done for the WOLVES stock. Each flow is calculated in terms of the variables, and stocks that are linked to it.

HOW TO USE IT

Press the SETUP button.
Press the GO button to run the model.
View the SHEEP and WOLVES monitors for the current value of those populations.
View the plot to observe the populations changing over time.

THINGS TO NOTICE

What happens when the sheep population increases? And the wolves? Why do you think this is the case?

THINGS TO TRY

Use the System Dynamics Modeler to change the values of the variables in the system, such as SHEEP-BIRTH-RATE and PREDATOR-EFFICIENCY.

NETLOGO FEATURES

This model uses the System Dynamics Modeler to simulate the Lotka-Volterra equations.

RELATED MODELS

Wolf-Sheep Predation Wolf-Sheep Predation (docked)

CREDITS AND REFERENCES

Lotka, A.J. (1956). Elements of Mathematical Biology. New York: Dover.
"Lotka-Volterra equation". From Wikipedia. http://en.wikipedia.org/wiki/Lotka-Volterra_equation
Eric W. Weisstein. "Lotka-Volterra Equations." From MathWorld. http://mathworld.wolfram.com/Lotka-VolterraEquations.html

HOW TO CITE

If you mention this model in a publication, we ask that you include these citations for the model itself and for the NetLogo software:

Wilensky, U. (2005). NetLogo Wolf Sheep Predation (System Dynamics) model. http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation(SystemDynamics). Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL.
Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL.

COPYRIGHT AND LICENSE

CC BY-NC-SA 3.0

This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.

Commercial licenses are also available. To inquire about commercial licenses, please contact Uri Wilensky at uri@northwestern.edu.

Comments and Questions

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Click to Run Model

;; system-dynamics-setup, system-dynamics-do-plot, and system-dynamics-go are automatically
;; generated by the System Dynamics Modeler.  The code can be viewed in the
;; Code Tab of the System Dynamics Modeler.

to setup
  clear-all
  system-dynamics-setup
  system-dynamics-do-plot
end 

to go
  system-dynamics-go
  system-dynamics-do-plot
end 


; Copyright 2005 Uri Wilensky.
; See Info tab for full copyright and license.

There are 10 versions of this model.

Uploaded by	When	Description	Download
Uri Wilensky	over 11 years ago	Updated to NetLogo 5.0.4	Download this version
Uri Wilensky	about 12 years ago	Updated version tag	Download this version
Uri Wilensky	about 12 years ago	Updated to version from NetLogo 5.0.3 distribution	Download this version
Uri Wilensky	almost 13 years ago	Updated to NetLogo 5.0	Download this version
Uri Wilensky	over 14 years ago	Updated from NetLogo 4.1	Download this version
Uri Wilensky	over 14 years ago	Updated from NetLogo 4.1	Download this version
Uri Wilensky	over 14 years ago	Updated from NetLogo 4.1	Download this version
Uri Wilensky	over 14 years ago	Updated from NetLogo 4.1	Download this version
Uri Wilensky	over 14 years ago	Model from NetLogo distribution	Download this version
Uri Wilensky	over 14 years ago	Wolf Sheep Predation (System Dynamics)	Download this version

Attached files

File	Type	Description	Last updated
Wolf Sheep Predation (System Dynamics).png	preview	Preview for 'Wolf Sheep Predation (System Dynamics)'	over 11 years ago, by Uri Wilensky	Download

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