Species-specific markers
The most important peaks for species identification including all peaks with a maximum of class-specific mean decrease in accuracy of more than 0.015 (leading to 170 important peaks) were derived from the final species RF model. Species-mean Euclidean distances were calculated using the R package vegan (Oksanen et al., 2017) based on individual distances using intensities of the whole peak spectrum and used for hierarchical clustering with average linkage.