Abstract
Ecological explanations for the success and persistence of invasive species vastly outnumber evolutionary hypotheses, yet evolution is a fundamental process in the success of any species. The Evolution of Increased Competitive Ability (EICA) hypothesis (Blossey and Nötzold 1995) proposes that evolutionary change in response to release from coevolved herbivores is responsible for the success of many invasive plant species. Studies that evaluate this hypothesis have used different approaches to test whether invasive populations allocate fewer resources to defense and more to growth and competitive ability than do source populations, with mixed results. We conducted a meta-analysis of experimental tests of evolutionary change in the context of EICA. In contrast to previous reviews, there was no support across invasive species for EICA's predictions regarding defense or competitive ability, although invasive populations were more productive than conspecific native populations under noncompetitive conditions. We found broad support for genetically based changes in defense and competitive plant traits after introduction into new ranges, but not in the manner suggested by EICA. This review suggests that evolution occurs as a result of plant introduction and population expansion in invasive plant species, and may contribute to the invasiveness and persistence of some introduced species.
Highlights
In the research effort to identify and explain the success of invasive species in their new range, evolutionary explanations for invasiveness are rarely invoked
We found no general support across invasive plant species for reduced defenses in the introduced range of invaders
Contrary to the Evolution of Increased Competitive Ability (EICA) hypothesis, there was no reduction in defense in the introduced ranges of invasive species across the 19 studies (176 comparisons) in which some metric of defense was evaluated, which suggests that release from herbivory is not in general a powerful selective force upon plant defenses in invasive species
Summary
In the research effort to identify and explain the success of invasive species in their new range, evolutionary explanations for invasiveness are rarely invoked. Studies that link invasions to evolutionary interactions between invasive plants and their new environment represent a small fraction of invasive species research (Lee 2002; Kollmann and Banuelos 2004; Prentis et al 2008; Alexander et al 2009; Allan and Pannell 2009; Hornoy et al 2011; Haider et al 2012), despite the importance of local adaptation in determining the distribution and success of some native plant species (Macel et al 2007; Alvarez et al 2009; Kawakami et al 2011). The most prominent of the hypotheses of plant invasion which invoke evolution of invasives, the Evolution of Increased Competitive Ability (EICA) hypothesis (Blossey and No€tzold 1995), proposes that evolution of invasive populations occurs as a release from coevolved herbivores, not in response to selective factors in the environment of the new range
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
