Two colonisation stages generate two different patterns of genetic diversity within native and invasive ranges of Ulex europaeus

Genetic diversity and the way a species is introduced influence the capacity of populations of invasive species to persist in, and adapt to, their new environment. The diversity of introduced populations affects their evolutionary potential, which is particularly important for species that have invaded a wide range of habitats and climates, such as European gorse, Ulex europaeus. This species originated in the Iberian peninsula and colonised Europe in the Neolithic; over the course of the last two centuries it was introduced to, and has become invasive in, other continents. We characterised neutral genetic diversity and its structure in the native range and in invaded regions. By coupling these results with historical data we have identified the way in which gorse populations were introduced and the consequences of introduction history on genetic diversity. Our study is based on the genotyping of individuals from 18 populations at six microsatellite loci. As Ulex europaeus is an allohex...