Rapid Loss of Phenotypic Plasticity in the Introduced Range of the Beach Daisy, Arctotheca Populifolia

1. Phenotypic plasticity is thought to be beneficial for species when introduced to a new range, increasing their proficiency in colonising and expanding into new environments. It has been hypothesised that an increase in phenotypic plasticity can be selected for when introduced to a new range.2. We set out to determine whether there was greater phenotypic plasticity in introduced populations of Arctotheca populifolia, compared with their native source population.3. We compared levels of phenotypic plasticity in four introduced Australian populations with the one identified source population from South Africa, across two separate glasshouse experiments that varied availability of (i) nutrients and (ii) water. Phenotypic plasticity was assessed at the population level for 13 individual traits, and across a suite of traits using a meta-analysis to determine whether there was an overall difference in plasticity between ranges.4. The Australian populations had a significantly lower composite plasticity in response to nutrient availability (-0.56 [95% CI: -0.99; -0.13]), as well as lower plasticity in response to water availability, though this was not significant (-0.36 [95% CI: -0.80; 0.07]).5. Synthesis. Contrary to our expectations, A. populifolia has lower phenotypic plasticity in its introduced range than in its native range. This may have resulted from founder effects, or from rapid changes in plasticity due to selective pressures differing between the native and introduced ranges.