Phenotypic plasticity hypothesis.

Abstract

Abstract The phenotypic plasticity hypothesis - or, in short, plasticity hypothesis - posits that invasive species are more phenotypically plastic than non-invasive or native ones. On the basis of a systematic review, we identified 115 relevant empirical tests of the plasticity hypothesis. Most of these empirical studies focused on terrestrial plants; only some have been carried out on animals or in aquatic habitats. The plasticity hypothesis is largely empirically supported, including most of its sub-hypotheses - focusing on phenotypic plasticity in morphology, physiology and life history - and across taxonomic groups and habitats. There are relatively few experimental field and enclosure studies available, and these showed significantly lower support than observational studies. Similarly, recent studies showed slightly lower support of the plasticity hypothesis than early ones but this difference was not statistically significant. Thus overall, this invasion hypothesis is largely supported by currently available evidence; however, more studies are needed on organisms other than plants and in aquatic habitats, and it seems important to perform more experimental field and enclosure studies in the future to scrutinize this hypothesis.