Contemporary evolution during invasion: evidence for differentiation, natural selection, and local adaptation

Abstract

Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST-FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change.

Understanding and monitoring the consequences of human impacts on intraspecific variation

“…In addition, phenotypic and genetic changes have been observed in many introduced species and the native species with which they interact (Hendry et al., 2008; Mooney & Cleland, 2001). Although the extent to which these changes are adaptive is not always certain (Colautti & Lau, 2015), evolution in introduced species is predicted to influence the rate, extent, and impact of invasions (García‐Ramos & Rodríguez, 2002; Vázquez‐Domínguez, Suárez‐Atilano, Booth, González‐Baca, & Cuarón, 2012). Thus, novel selective pressures can lead to evolutionary changes in both native and invasive species that then influence the abundance of those species, with expected further consequences for intraspecific variation.…”

Transatlantic invasion routes and adaptive potential in North American populations of the invasive glossy buckthorn,Frangula alnus

“…Correspondingly, seven of these SNPs were assigned a role in reproduction, one of the most influential life-history traits of plants in governing evolutionary responses to environmental change (Barrett, 2011). The low density of conspecifics during range shifts in the invasive range may have facilitated the evolution of traits increasing reproduction (Phillips et al, 2010;Parker et al, 2013;Colautti and Lau, 2015). Adaptive shifts towards more reproductive genotypes may have strong consequences for native species' communities, stressing the need for management actions aiming to reduce gene flow from nurtured park populations into invasive natural populations.…”

Selecting for invasive tendencies: the evolution of morphological, physiological, and movement behaviour traits associated with dispersal

“…Many invasive species (including amphibians, birds, fish, and insects) have been found to exhibit certain traits that assist in their dispersal ability, and rapid phenotypic change occurs at expanding range edges (Llewelyn et al 2010;Berthouly-Salazar et al 2012;Laparie et al 2013;Myles-Gonzalez et al 2015;Davenport & Lowe 2016). As climate change and anthropogenic disturbance of natural systems continues, the importance of understanding biological invasions grows, therefore elucidating the impact of evolutionary processes in the spread and ecological impact of invasive species is a vital component of this understanding (Colautti & Lau 2015). Crucially, the evolution of dispersal syndromes is not easily disentangled from environmental variation and stochastic processes that are found at natural range edges; therefore our understanding of selective processes on dispersal is constrained.…”

“…Both of these evolutionary mechanisms are prevalent in shaping traits that are associated with accelerating range expansion in invasive species, including birds (Berthouly-Salazar et al 2012), toads (Shine et al 2011;Lindström et al 2013), fishes (Rehage & Sih 2004;Myles-Gonzalez et al 2015), salamanders (Lowe & McPeek 2012;Davenport & Lowe 2016), mites (Van Petegem et al 2015;2016a), and insects (Piiroinen et al 2011;Laparie et al 2013). Understanding trait evolution is a pre-condition for elucidating factors that contribute to shifts in the distributions of invasive species; such shifts have potentially dire consequences for the ecology of native species and the conservation of natural environments (Colautti & Lau 2015). …”