Figure 1.

Ontogenetic trajectories. (A) The ontogenetic trajectory of an organism is shown as a point moving in three dimensions: size (S), shape (σ), and age (a). (B) Linearized ontogenetic trajectories are shown as a plot of shape (σ) versus age (a). Species 2 can achieve a final shape that is different to that of species 1 either by having a different rate of shape change (2), a different time of onset of growth (2′), or a delayed offset (2′′). (C) Species 1 has determinate growth, whereas species 2 has indeterminate growth. By showing plots of shape versus age, rather than size versus age, the growth characteristics of species that differ considerably in size can be easily compared.