Figure 1

Heat map of all 60 + compounds from the males and females of all Sarcophaga species, showing gender, time and species-dependent differences in the chromatograms. The historical samples cover a time period which ranges over 117 years. The x-axis represents the retention time and the chromatographs are grouped along the y-axis by species. The heat map is a visual aid, enabling multiple chromatographs to be efficiently stacked for comparison in a small vertical space, in which darker spots represent larger peak areas. For example, the most abundant compound, with a retention time of around 22.1 min on the heat map, is C27 (Table S1, peak number 23, Table S2, peak number 35). Some individual S. pumila female samples exhibited chromatograms that appeared different on the heat map. Nevertheless, SVM correctly classified all of these specimens as S. pumila. The compounds used for classifying are presented in Table S3.