Allocation to growth versus differential extrinsic mortality for the eight parasitic castrator trematode species (operating stolen host bodies) and both genders of uninfected horn snails. (A) The analysis using species as independent data points (r = -0.86, P = 0.0014, n = 10). (B) The analysis using phylogenetically independent comparisons (r = -0.81, P = 0.0060, n = 9; regression through the origin: t8 = 4.0, P = 0.004). Total growth allocation is the area underneath the species' growth curves in Figure 1, calculated as the definite integral with limits at the minimum- and maximum-sized snail averaged across species. Differential mortality is the mean proportion of individuals killed by dominant trematodes, or, for uninfected snails, reproductively killed by trematodes. Symbol numbers indicate species as numbered in Figure 1 and Additional file 1, Table S1. Symbol letters indicate locations of contrasts in the phylogeny depicted in Figure 4. Open symbols represent uninfected snails or contrasts involving uninfected snails. Fit lines are the standard major axes, reflecting the bivariate nature of the data.