Table 1. Results of GLM analysis (with quasi-binomial error structure) of differences between the two lichen species (generalist versus specialist lichen species as fixed factor) and among the nine snail species (as random factor) in lichen regeneration rates.

	Regeneration rate of lichens
Source of variation	df	Deviance	F	p
Lichen species	1	12.51	18.256	0.003
Snail species	8	99.15	18.080	<0.001
Snail mass	1	46.41	6.160	0.042
Residual variation among snail species	7	52.74	10.992	0.002
Lichen species×snail species	8	5.75	0.386	0.927
Residuals	188	401.4

The model also included snail body mass as linear contrast and the interaction between lichen and snail species.