Summary of the results of General Additive Modeling of shell polymorphism in Cepaea nemoralis in the combined dataset of historical and 2009 samples collected throughout Europe.

Statistics shown are coefficients (α) and t-values for unsmoothed terms and F-values for smoothed terms. P-values are approximate. n = sample size (number of populations), Dev% is the percent deviance accounted for by the model. Mid-banded frequency is calculated as a percentage of banded. Coefficient values are not given for the terms entered as smooth functions, because such function cannot be described by a single coefficient.†In this case the model omitting Habitat as an independent variable fits slightly better in terms of deviance than the model including Habitat, so no test statistic or p value can be calculated.