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FIGURE 11.18 Change confined to
early morphogenesis. (A) Superimposed
coordinates of juvenile shapes; (B) onto-
genies of shape; (C) lengths of ontoge-
netic vectors of shape. The two species
differ in shape at the outset of the mea-
sured phase, but subsequently follow
the same ontogeny of shape and do not
differ in the length of their ontogenetic
vectors.
shown in Figure 11.18 , the difference between their shapes at the transition from larval to
juvenile phases is highly significant (P
0.0001) and the Procrustes distance between their
means is large: 0.1247. The contrast between the shapes is particularly striking in the
superimposed coordinates because we find little or no overlap between species in several
of them ( Figure 11.18A ). But, as anticipated, there is no significant difference in their onto-
genies of form; the angle between the two vectors is a tiny 1.9 (compared to the within-
species angles of 4.0 and 3.7 ). And the lengths of the ontogenetic vectors are statistically
indistinguishable; the Procrustes distance between the youngest and oldest for one species
is 0.1999 and for the other it is 0.2040. Thus, all that differs between the two trajectories is
the shape at the outset of development. We can thus test for a difference between shapes
at the youngest comparable stage, a difference between the ontogenies of shape and a dif-
ference in length of the ontogenies. Piras and colleagues ( Piras et al., 2011 ) suggest testing
the hypothesis of no transposition of the allometries, which is equivalent to a test of no dif-
ference in elevation of the parallel trajectories, using the distance between the predicted
intercept shapes, comparing that distance to a distribution of distances obtained by
,
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