Phenotypic plasticity and genetic diversity in Poa annua L. (Poaceae) at Crozet and Kerguelen Islands (subantarctic)

Abstract

The widely distributed grass, Poa annua, is one of the most common alien species in the subantarctic islands. The historical events of its introduction remain generally unknown, as well as the evolutionary consequences of its colonisation in these remote environments. Populations from the Crozet archipelago and Kerguelen Islands were compared in terms of morphology, cytogenetics and enzyme polymorphism. Seeds from natural populations were also sown in an experimental garden in France to test phenotypic plasticity. This preliminary study demonstrated the high phenotypic plasticity in P. annua in the French subantarctic islands. This plasticity and allotetraploidy could be important factors which reinforce the colonising capacities of P. annua. Our results revealed the low genetic diversity of the populations analysed, which could be related to the founding effect or to the fragmentation of the populations.