Biology 120: creating a modeling lab

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Biology 120creating a modeling lab

• Nathaniel Meyer, Louis Weiss, Lauren Shuler

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Background

• Target Audience
• Genetics, Evolution, Ecology Students and
  teachers (Biology 120)
• Teaching Objectives
• Provide an introduction to modeling and the
  systems perspective
• Reinforce Understanding of population dynamics
  the
• Lotka-Volterra predator-prey model
• r- k-selected species
• Build the associated model and draw conclusions
  based on findings
• Lotka-Volterra (predator-prey) oscillations
• Given a model and an interface, allow the
  students to explore system dynamics by
  systematically changing coefficients

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Pedagogy

• Thought process
• How can we best create a lab exercise that
  provides enough information to give students a
  basis for exploring the concepts on their own?
• Is building or exploring more effective at first?
• How do we avoid a recipe book lab?
• What questions do we ask to stimulate the
  students?
• Which concepts in the Biology 120 curriculum
  would be most appropriate for a modeling lesson?
• Which can be most effectively taught using
  modeling?
• Which is the best vehicle to teach modeling?

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Structure

• Presented background on modeling including STELLA
  software
• Introduced the systems perspective i.e. stocks,
  flows, and feedback
• Guiding steps through the exponential (r-selected
  species) model
• Expand the exponential model to include a
  carrying capacity (k-selected)
• Provide an interface for the Lotka-Volterra model

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r-selected Species

• Purpose of this model
• Introduce the students to the STELLA software and
  modeling
• Create a simple model of exponential growth
  without a limiting resource
• Help them understand what r means in
  r-selected
• Formulation Exponential Growth
• dN/dt RN
• NPert

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Adding k (carrying capacity) to the model

• Purpose of this model
• Expand the students knowledge of STELLA by
  creating a more complicated model
• Help students understand what k means in
  k-selected
• Allow them to play with coefficients to see what
  factors most heavily affect the system
• Formulation Logistic Growth
• dN/dt rN(K-N) rNK CN2 (second order
  loss, first order growth)

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r- k-selected species Interface
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Exploring Lotka-Volterra

• Purpose of this model
• Allow the students to explore predator-prey
  population dynamics using a previously created
  model
• Systematically change coefficients to examine the
  effect of each on system dynamics
• Address feedback loops and explore their
  implications in this model

Feedback Loop
(-)
Prey
Predator
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Calibration

• We roughly calibrated the model to Hudson Bay
  pelt data to find the correct coefficient values.
  
• We then reset the values and challenged the
  students to calibrate the model as well.

Year Hares (x10) Lynx (x10)
0 300 40
2.7 470.2 60.1
5.4 700.2 90.8
8.1 770.4 350.2
10.8 360.3 590.4
13.5 200.6 410.7
16.2 180.1 190
18.9 210.4 130
21.6 220 80.3
24.3 250.4 90.1
27 270.1 70.4
29.7 400.3 80
32.4 570 120.3
35.1 760.6 190.5
37.8 520.3 450.7
40.5 190.5 510.1
43.2 110.2 290.7
45.9 70.6 150.8
48.6 140.6 90.7
51.3 160.2 100.1
54 240.7 80.6
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Current Bio120 Student Reactions

• Fit the lab to the current Bio 120 lab structure
  (break down into separate parts)
• More explicit directions
• Cover more of the material discussed in lecture
• It would have been nice to see a simple
  ecological model prior to constructing their own
  (phytoplankton nutrients)
• Allow for more hypothetical thinking maybe tell
  us to conceptualize a food web model
• We thought we could apply what we learned more
  extensively (i.e. analogies)

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Conclusions

• We need to spend more time working directly with
  students who are unfamiliar with systems
  modeling.
• The balance between too much and too little
  information is difficult to achieve.
• This project and its integration into the biology
  program is entirely feasible.

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In the Future

• Meet with the three BIO 120 lab instructors and
  John (during commencement, John?) to review our
  exercise and discuss improvements.
• Explore other possible biology topics to be used
  in this exercise.
• Give the lab to more biology students (without
  modeling background).