Sensitivity and elasticity Flashcards
Define Elasticity (equation define)
product of value of matrix element and sensitivity of that element, divided by asymptotic growth rate
Elasticity analyses
scale sensitivity to units. Elasticities are proportional sensitivities scaled so that they are dimensionless and directly comparable
Right eigenvector ( _ )
w
Left eigenvector ( _ )
v
define right eigenvector
age or stage class structure, when the stable state is reached. Stabilized proportion of each age class. column vector
define left eigenvector
reproductive value or worth of each age/stage class row vector
Sensitivity analyses
how small changes in fertility and Probability (transition and staying in same stage) will affect lambda when others are held constent the values indicate the factor by which lambda will change. Sensitivity is represented as a slope, the most sensitive matrix elements produce the largest slope
What does sensitivity analysis tell us in terms of management perspective
identify the life history stage that will contribute the most to population growth of a species.
how to determine left eigenvector
transpose the matrix, then multiply with matrix algebra the transposed matrix times the number in each age or stage class
asymptotic population growth rate
when the growth rate (lambda) has stabilized when multiplying many iterations of the matrix
eigenvalue
value of lambda when population has stabilized when the eigenvalue (numbers) is multiplied by a vector of abundences yields same result as matrix multiplied by vector of abundances.
Sensitivity (equation)
Sij= (vw)/()
Computing sensitivity
- running the projection model until population reaches stable distribution 2. calculate w (stable stage structure) 3. calculate v (reproductive values) 4. calculate sensitivity equation
scalar
single number product of the w and v - need to adjust so v*w will give a single number.
Elasticity analysis estimates?
the effect of a proportional change in the vital rates on population growth