Predation risk alters shape
Analysis of Daphnia shape using Procrustes ANOVA revealed that
shape varied across all factors, including size, instar, clone and
predation risk (all p < 0.001). The response to the level of
predation risk did not vary by instar (predation x instar interaction; F
= 1.39, df = 5, p = 0.13), but it did vary by genotype (predation x
genotype interaction; F = 4.92, df = 10, p < 0.001). The
phenotypic trajectory analysis showed that this interaction was not
based around how much the clones responded to predation cues (path
distances were equivalent, all pairwise differences p >
0.05), but around differences in the direction of these changes in
multivariate trait space (the angle of the change in shape space) and
the shape of these changes (the relative position of the changes in
shape space, all pairwise differences p < 0.01) along the six
cue concentration gradient (Fig. 3-5). Specifically, the direction of
change in clone ‘Cletus’ differed from both clone ‘Chardonnay’ and
‘Carlos’ (both p < 0.05) indicating that the landmarks that
changed in ‘Cletus‘ were different than in the other two clones and we
can see the evidence for differences in the shape of the trajectories in
Fig. 5, where each clone follows a slightly different path along the cue
concentration gradient.