Invasive plants, in particular, are believed to double-profit from a loss of their natural enemies and subsequent evolution of less chemically defended but more competitive genotypes which then take over their new habitats. A recent study soon to appear in Ecology Letters, however, suggests something different.
In an experiment conducted by researchers at the Centre for Environmental Research in Halle, Germany, offspring from invasive North American populations of garlic mustard (Alliaria petiolata) were outcompeted by those from native European populations. Hence the species has evolved to be less rather than more competitive, probably due to a lack of strong competitors in the invaded habitats.
Journal
Ecology Letters