[R-sig-eco] glmer , quasipoisson and standard errors of the coefficients

[Albert Romero]

Hello,
I am trying to simplify backwards a mixed effects model, using lmer 
function from lme4 package. As my data are species numbers and there 
exists overdisperison, I think appropriate to use glmer function with 
error family quasipoisson. I compare one model with its simplification 
through log-likelihood ratio tests.
Nevertheless, once I have selected a simplified model, I find in the 
summary of this 'significant' model that estimated coefficients  are  
associated  to  very big  standard errors, to the point that no one of 
the coefficients seem to be significantly different from zero.

Here come my questions:
Can anybody explain this contradiction among standard errors of the 
estimated coefficients and the significance of the model?
Is unappropriated to use Log-likelihood backwards simplification with 
quasipoisson errors?

Thank you in advance!

-- 
Albert Romero Puente
Departament de Biologia Vegetal-Botànica
Universitat de Barcelona
Facultat de Biologia
3a Planta
Av. Diagonal, 645. (08028) Barcelona
Tel. 0034 93 402 14 71