The relative contribution of plasticity and evolution to
metabolite changes
For both transitions between two successive periods differing in fish
predation pressure we calculated the total peak change of important
metabolites (VIP >1), i.e. the peak change as would be
observed when comparing the Daphnia under the period-specific
kairomone treatments (absence of fish kairomones in the pre-fish and
reduced-fish periods, and presence of fish kairomones in the high-fish
period), following the method described in (Stoks et al. 2016).
We partitioned the total change for each important metabolite into three
components: ancestral plasticity, constitutive evolution and evolution
of plasticity (see Figure S1 in Supplementary Information). Ancestral
plasticity refers to the plasticity present in the older period of a
given transition. Constitutive evolution refers to evolution of the mean
in the ‘ancestral’ kairomone condition for a given transition between
periods, hence in the absence of fish kairomones when going from the
no-fish to the high-fish period and in the presence of fish kairomones
when going from the high-fish to the reduced-fish period. Evolution of
plasticity refers to the change in the slope of the reaction norm and is
the remainder of the total trait change after subtracting ancestral
plasticity and constitutive evolution from total phenotypic trait change
(see Figure S1).