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.