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Pre-juveniles. Adults. Juveniles. Create a conceptual model. Assume 3 stages for the toads. A Toad Transition Matrix. 0 18 1000 0.02 0.2 0 0 0.01 0.75. (based on Biek et al. 2002). Sensitivity analysis. Sensitivity: changes in popn growth rate with respect to changes in
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Pre-juveniles Adults Juveniles Create a conceptual model Assume 3 stages for the toads
A Toad Transition Matrix 0 18 1000 0.02 0.2 0 0 0.01 0.75 (based on Biek et al. 2002)
Sensitivity analysis Sensitivity:changes in popn growth rate with respect to changes in life cycle transitions Elasticity: sensitivities scaled so that they are proportions- sum to 1.0 Change 1 element in matrix at a time (EXCEL DEMO)
So what does this tell us? We know that adults, pre-metamorphs, and eggs are all important to population persistence. NOW WHAT?
Using sensitivity analysis results The peregrine falcon (Falco peregrinus) 0 0.004 0.091 0.095 0.036 0 0 0.091 0.683 Elasticity matrix
Other considerations…. What about variation? • demographic • environmental
Summary Sensitivities and elasticities are rates of change- slopes. They have biological interpretations but must be used carefully They can be very helpful in determining which management actions will be most effective
Ungraded Homework 1. What is the biological interpretation of the matrix element a34? 2. Why can’t an elasticity or sensitivity analysis alone be used as the basis for choosing a management strategy?