Increased competitive ability in an invasive plant

A common hypothesis explaining plants’ invasive success is the evolution of increased competitive ability (EICA). Joshi et al. study the invasive plant Lythrum salicaria (purple loosestrife) and carefully distinguish between competitive effects and responses of invasive and native plants, under both intra- and interspecific competition. They find that while intraspecific competition results in no differences in competitive effects or responses between native and invasive plants, interspecific competition produces greater competitive effects and responses of invasive plants in terms of both biomass and seed production. They conclude that under interspecific competition there is strong support for the EICA hypothesis, with an evolutionarily increased competitive ability in invasive populations of L. salicaria.