[R-sig-eco] DemoInfo {primer} output -lambda the same as RV

[Jennifer Peterson]

Hello,

I am using the DemoInfo function in the primer package in R to calculate individual fitness for insects at different ages that are infected with different parasites. 

The time is set in months, and insects only reproduce in their 2nd and 3rd months out of 4 months. I am constructing the matrix as described in Caswell 2001 and in McGraw and Caswell 1998.

 In running the models, the lambda value is always the same as the reproductive value for the 2nd month, except when the insect didn't reproduce until it's 3rd month, in which case the lamda is negative. 
 It seems strange that reproduction in the 3rd month doesn't influence the lambda.

Could anyone tell me if this is normal ( I mean the laymen's definition of normal)?

Here are 2 examples:

Example 1

con9  <- matrix(c(0,27,23,0,1,0,0,0,0,1,0,0,0,0,1,0),byrow=TRUE,nrow=4)
DemoInfo(con9)

$lambda
[1] 5.578778

$SSD
[1] 0.821597491 0.147271940 0.026398601 0.004731968

$RV
[1] 1.000000 5.578778 4.122767 0.000000

$Sensitivities
          [,1]       [,2]       [,3]        [,4]
[1,] 0.4689402 0.08405788 0.01506743 0.002700848
[2,] 2.6161136 0.46894024 0.08405788 0.015067434
[3,] 1.9333311 0.34655099 0.06211951 0.011134967
[4,] 0.0000000 0.00000000 0.00000000 0.000000000

$Elasticities
          [,1]       [,2]       [,3] [,4]
[1,] 0.0000000 0.40682073 0.06211951    0
[2,] 0.4689402 0.00000000 0.00000000    0
[3,] 0.0000000 0.06211951 0.00000000    0
[4,] 0.0000000 0.00000000 0.00000000    0

$PPM
     [,1] [,2] [,3] [,4]
[1,]    0   27   23    0
[2,]    1    0    0    0
[3,]    0    1    0    0
[4,]    0    0    1    0

Example 2

con16 <- matrix(c(0,0,15,0,1,0,0,0,0,1,0,0,0,0,1,0),byrow=TRUE,nrow=4)
DemoInfo(con16)

$lambda
[1] -1.233106

$SSD
[1]  1.19406646 -0.13010412 -0.14356677  0.07960443

$RV
[1] 1.000000 2.466212 6.082202 0.000000

$Sensitivities
              [,1]         [,2]         [,3]          [,4]
[1,] -3.585065e+15 3.906246e+14 4.310448e+14 -2.390043e+14
[2,] -8.841530e+15 9.633630e+14 1.063048e+15 -5.894353e+14
[3,] -2.180509e+16 2.375858e+15 2.621702e+15 -1.453673e+15
[4,]  0.000000e+00 0.000000e+00 0.000000e+00  0.000000e+00

$Elasticities
            [,1]          [,2]          [,3] [,4]
[1,] 0.00000e+00  0.000000e+00 -5.243404e+15    0
[2,] 7.17013e+15  0.000000e+00  0.000000e+00    0
[3,] 0.00000e+00 -1.926726e+15  0.000000e+00    0
[4,] 0.00000e+00  0.000000e+00  0.000000e+00    0

$PPM
     [,1] [,2] [,3] [,4]
[1,]    0    0   15    0
[2,]    1    0    0    0
[3,]    0    1    0    0
[4,]    0    0    1    0



Thank you very much for your help.

All the best,
Jennifer Peterson
--
----------------------------------------------------------------
Jennifer K Peterson
PhD Candidate
Dobson & Graham Groups
Dept. of Ecology and Evolution
Princeton University
jkpeters at princeton.edu
www.jennipeterson.com
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