Spectra of objects studied in the experiment. Comparison of the spectra of a sample of snails from the same colour morphs as those studied in the experiment (autochthonous and allochthonous lineata, nigra and lutea) and a random sample of rocks from Cabo Silleiro, ‘Rocks (autoch.)’. Each line represents the mean of all measured objects within a class, and the shaded area their corresponding 95% confidence intervals.