Integrating Ecological and Evolutionary Theory of Biological Invasions

Abstract

While research on biological invasions is becoming more predictive (e.g., Mack 1996; Kolar and Lodge 2001; Peterson 2003; Arim et al. 2006; Mitchell et al. 2006), significant challenges lie ahead. Indeed, it is still not clear what leads some introduced species to remain benign while others become aggressive invaders. Here, we review some principal ecological and evolutionary hypotheses employed to explain biological invasions.We present an overview of these hypotheses, and suggest approaches to integrate them into a more comprehensive framework that will allow potential interactions among them to be examined. Biological invasions are spatially and temporally continuous processes, encompassing transport, establishment and spread phases (Sakai et al. 2001). We focus here on the spread, or demographic expansion, of non-native species that are established, since this stage will ultimately determine an invader’s impact in a novel environment. Demographic expansions of introduced species can encompass changes within individuals, such as increase in size or fecundity, and within populations, such as increase in geographic spread and density. We refer to demographic expansions of introduced species as invasion success.