[R-sig-ME] Bivariate random regression model in MCMCglmm to estimate selection on reaction norm slopes
j.hadfield at ed.ac.uk
Sat Mar 28 08:47:52 CET 2015
The correct syntax (assuming fitness is an annual measure so you have
repeat records?) is:
Quoting Phillip Gienapp <phillip.gienapp at helsinki.fi> on Wed, 18 Mar
2015 11:25:07 +0100:
> Dear all,
> First a bit of background: I currently work on an anlysis of
> phenotypic plasticity of avian phenology in response to temperature.
> Using a random regression model I found that individual reaction
> norms (defined by slope and intercept) vary among individuals, i.e.
> some individuals change their phenology more strongly in response to
> temperatures than others and also that some individuals have a
> consistently earlier phenology than others.
> I now want to test whether there is selection on reaction norm
> slopes, i.e. whether individuals with steeper/shallower slope have a
> higher/lower fitness. This means I have to fit a bivariate random
> regression model but only one trait (phenology) should be regressed
> against temperature. For the random effects part this should give me
> a 3x3 covariance matrix with variation in slopes, intercepts,
> fitness plus all the covariances and then the covariance between
> slope and fitness indicates selection on reaction norm slopes.
> I figured how to regress only phenology and not fitness against
> temperature for the fixed effects part but am still struggling with
> the syntax for the random effects part.
> The univariate random regression model (omitting obvious syntax parts) is:
> phenology~age + temp, random=~us(1+temp):individual
> For the multivariate model I came up with:
> cbind(phenology,fitness)~trait:age + at.level(trait,1):temp,
> but curiously this fits only a single variance for individual and
> not the desired 3x3 matrix...
> I hope I managed to explain my problem clearly enough (maybe there
> was too much non-technical detail...). Any ideas to fit the desired
> model are highly welcome!
> R-sig-mixed-models at r-project.org mailing list
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
More information about the R-sig-mixed-models