Fig. 4

Bar plots of the frequency of DARs of each type (types 1–7 plotted from left to right using the same colors as referenced in Tables 1, 2, and used in Fig. 3) between sexes (top left two plots), ages (bottom left two plots) and DARs originating at three different locations (see text for discussion). Chi-squared contingency table analyses of these three comparisons (sex, age, location) are all highly significant (\(p<0.001)\)—see Additional file 1: Table A.3 in Appendix A for details