Neckteeth, head height and belly-bulge
The principal component axes underlying the trajectory analysis indicated that 55% of variation in shape was captured by the first PC, rising to 71% with PC2 and 83% with PC3. A visualisation of the trajectories in 2D PC space, along with detail on what shapes were associated with the PC-axes, revealed several key insights (Fig. 3-5). Based on the deformation grids outside the PC-axes, we were able to define PC1 as neck-change (i.e. the inducible defence), PC2 as head height and PC3 as belly-bulge.
Fig. 3 revealed that the most significant change in shape occurred along PC1, the inducible defence. The trajectories of all three clones moved in parallel to PC-axis 1, which showed that the neck region was larger when there was more cue. Also, there were clear differences among the genotypes linked to head height (PC2 axis). We suggest that this is largely representative of clone differences, as Fig. 3 and 4 indicated relatively large differences between genotypes compared to the effect of the cue concentration.