Figure 3
Comparison of peptide, PMS and spectra methods for determining species. (A) Comparison of distribution of ratios for correctly and incorrectly identified bone samples of known species, results from a mammal database search. (a) Non-redundant peptide/total peptides, (b) peptide-spectrum matches (PSM)—i.e. all (redundant) peptide identifications/total peptides, (c) all (redundant) spectra/total spectra. On average 77% of spectra were found two or more times with a mean of ~ 5.7 spectra for each sequence (median 3, range 6–55). As results are from a mammal database search, incorrectly identified samples include all seven non-mammal samples. Above each box plot is the total number of samples in each category. (B) Comparison of distribution of ratios (peptides or spectra assigned to human/total peptides or total spectra identified) for human and non-human bone samples using results from vertebrate database search. Descriptions of a–c same as (A). Rhesus macaque, the only non-human primate, is circled in red.
