Presentation is loading. Please wait.

Presentation is loading. Please wait.

Predicting predator-prey populations. Desired results.

Similar presentations


Presentation on theme: "Predicting predator-prey populations. Desired results."— Presentation transcript:

1 Predicting predator-prey populations

2 Desired results

3 Here’s an approximation of reality: The hare birth rate is constant, as their food supply is unlimited. Hares only die when eaten by a lynx, and the number of hares eaten is proportional to how often hares & lynxes meet, i.e., the chance of a lynx catching a hare. The lynx birth rate is also proportional to how often hares & lynxes meet, i.e., the food available for each lynx family. Lynxes only die from natural causes, and their death rate is constant. Lotka & Volterra, 1926 Dr. SiemannDr. Siemann, EEB

4 Computational Thinking Recipe (Algorithm) Relevant input Answer Abstraction Automation Problem description Computational goal Information extraction Algorithm design Algorithm implementation

5 Hares’ & Lynxes’ Populations Recipe (Algorithm) ??? Problem description Computational goal Information extraction Algorithm design Algorithm implementation

6 Algorithm Design – Decomposition 1.Generate population data. Repeatedly, a.Generate next populations of predator & prey. 2.Display population data.

7 Algorithm Design – Refinement 1.Store original populations. 2.Generate population data. Repeatedly, a.Generate next populations of predator & prey. b.Store new populations. 3.Display stored population data.

8 Lotka & Volterra, 1926 The hare birth rate is constant, as their food supply is unlimited. Hares only die when eaten by a lynx, and the number of hares eaten is proportional to how often hares & lynxes meet, i.e., the chance of a lynx catching a hare. The lynx birth rate is also proportional to how often hares & lynxes meet, i.e., the food available for each lynx family. Lynxes only die from natural causes, and their death rate is constant. Hare annual pop. change Lynx annual pop. change

9 Initially (Year 0) Year 1Year 2Year 3 # Hares 100 Hares born 4040 Hares eaten 15 #Lynxes 50 125 60 152 78 177 109 Lynxes die 10 Lynxes born 2020 50 23 12 30 61 36 16 47 71 58 22 77 + - - +.4.003.004.2 Hare annual pop. changeLynx annual pop. change Rounding all #s.

10 Algorithm Design – Refinement

11 Suggested Readings Predator-prey models Lotka-Volterra equation Wolves & Moose of Isle Royale – Esp. the Data sectionData – A technical paper about population cyclestechnical paper


Download ppt "Predicting predator-prey populations. Desired results."

Similar presentations


Ads by Google