One of the most exciting developments in invasion research in the past 10 years has been the injection of evolutionary thinking into our understanding of the causes, consequences, and dynamics of invasions. I will discuss two frameworks of evolutionary thinking, from both long- and short-time frames, which have already contributed to our understanding and which have the potential to produce rich insights in the future. First, phylogenetic ecology addresses how species are influenced by their evolutionary histories, which help shape their traits, distributions, and interactions. Second, contemporary evolution studies link genetics and natural selection to ecology, using invasions as a tool to capture evolution in action, while also helping to explain and manage invasions as dynamic processes.
Results/Conclusions
The predictions of phylogenetic ecology have the potential to shed light on major questions in invasion biology. First, Darwin’s Naturalization Hypothesis suggests that introduced species should be more successful invaders when they are phylogenetically isolated from the resident community, while habitat filtering predicts the opposite. Patterns of phylogenetic diversity across scales can identify the competing roles of these different mechanisms. Second, phylogenetic ecology helps predict when introduced species will escape natural enemies, because a strong phylogenetic signal in host range influences whether local pathogens will spill over onto novel hosts. Phylogenetic ecology offers quantitative predictions against which we can test how its power varies across systems and questions.
Microevolutionary studies illuminate many important aspects of the invasion process, including how adaptive evolution of the invader may increase its spread and impact, and conversely how evolution of native species in the recipient community may decrease the impact of the invader. Examples of traits that have shown rapid evolution during invasion include life history, dispersal, and mating system traits, among others. With very few exceptions, a missing piece of this research to date is to establish whether these evolutionary changes have contributed substantially to invasion success itself—that is, whether evolution is a driver or only a consequence of invasion. Another central question is whether invasiveness reflects a generalist strategy, as described by Baker’s concept of the general purpose genotype, or rather represents specialization to an increasingly anthropogenic world. The evolutionary dynamics of invasions have important implications for restoration and invasive species management.