[R-sig-ME] Deviations from normality in MCMC models

[Christopher Robinson]

MCMCglmm users,

I am trying to quantify correlated thermal reaction norms using bivariate
MCMCglmm models in R. Unfortunately, one of my variables is highly right
skewed and I cannot get the data to take on a normal (gaussian)
distribution. I've attached a histogram showing how my data look.

The MCMCglmm package in R allows users to specify the distribution family
for each variable. Unfortunately, I cannot fit a gamma distribution to my
data because MCMCglmm currently does not support this family. My question
is how sensitive to deviations from normality is MCMC? That is, if I apply
a gaussian distribution to this variable, will my results be strongly
affected?

An example of my code is as follows:

prior<-list(R=list(V=diag(2),nu=1.002),
            G=list(G1=list(V=diag(2),nu=1.002)))

modelHB<-MCMCglmm(cbind(Sprint,HB)~trait-1,
                  random=~us(trait):ID,
                  rcov = ~us(trait):units,
                  family=c("gaussian", "gaussian"),
                  prior=prior,data=data3,nitt=NITT,thin=THIN,burnin=BURNIN)

Thank you for any advice.

-- 
Chris Robinson
robinsoncd.weebly.com