Pre-adaption or genetic shift in the invasive alien plant Impatiens glandulifera
Impatiens glandulifera (Balsaminaceae: EPPO List of Invasive Alien Plants) is a highly invasive annual species within the EPPO region. The species originates from the Western Himalayas where it is found at altitudes between 2400 and 4400 m above sea level. Similar to other invasive alien plants, I. glandulifera has a high fecundity, rapid growth rates and displays a high phenotypic plasticity in the invaded range. It was unclear, however, if these characteristics are present in native populations (pre-adaptation hypothesis) or if they evolve following the introduction of the species (genetic shift hypothesis). To test these two hypotheses, seeds of I. glandulifera were collected from their invasive range (Norway) and the native range (India) and grown under greenhouse conditions. Plant growth parameters were measured and included plant height and aboveground biomass. Reproductive units were measured including the number of flowers, seeds per capsule and seed biomass. There was no evidence that seeds from invasive populations grew more vigorously or produced more seed compared to native populations, suggesting that I. glandulifera seems to be pre-adapted for invasion. The main factor for the invasive nature of the species could be attributed to differences in the native/introduced habitats where higher nutrient availability in the latter facilitate the invasion of I. glandulifera.
Sources
Elst EM, Acharya KP, Dar PA, Reshi ZA, Tufto J, Nijs I, Graae BJ (2016) Pre-adaption or genetic shift after introduction in the invasive species Impatiens glandulifera. Acta Oecologica 70, 60-66.