[R-sig-eco] Individual growth rate in a population with repeated sampling and overlapping cohorts

[Marc Taylor]

Dear Guiliano,

This seems like a typical dataset for modal progression analysis. I
unfortunately don't have experience with these types of analyses in R, but
perhaps you come across some tools using that terminology. In fisheries
science, the FiSAT program has often been used to fit growth models to such
data; and specifically the ELEFAN routine (Electronic LEngth Frequency
ANalysis). I found one attempt at the implementation of ELEFAN in R:
https://github.com/AaronGreenberg/ELEFAN
I personally had difficulties installing the package from GitHub.
Hope that helps you get started, and hopefully others chime in as well.

Cheers,
Marc



On Wed, May 6, 2015 at 5:41 AM, GiulianoC <gln.colosimo at gmail.com> wrote:

> Dear all,
>
> I am trying to infer the average individual rate for two different
> populations of iguanas. The two populations were established in 2002. Since
> then I have samples from the first borns in 2002 and then 2003, 2004, 2005,
> 2007, and 2009. Every time we sampled we caught as many individuals as
> possible. For the first 3 years of sampling it is fairly easy to assign
> individuals to the right cohort. For the remnant years I am not 100%
> positive to which cohort the newly captured individuals belong if they are
> larger than expected at hatching time.
>
> At each capture I take standard morphological measures (SVL in mm, mass in
> grams, head width and head length in mm). Since my samples sizes are not
> huge (52 in one pop and 140 in the other) I was planning to retain all my
> samples, even the recaptures over time.
>
> So, I was thinking about applying a non-linear mixed model to infer a rate
> of individual growth, but I am a little concerned about the overlapping
> cohorts issue.
>
> Any thought or suggestion is more than welcomed.
> Also, please let me know if I need to expand on my problem.
>
> Sincerely
>
> Giuliano Colosimo
> PhD Candidate in Conservation Genetics
> Dept. Biological Science
> Mississippi State University
>
>
>
> --
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>
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