Anthropogenically induced adaptation to invade (AIAI): contemporary adaptation to human-altered habitats within the native range can promote invasions

Abstract

Adaptive evolution is currently accepted as playing a significant role in biological invasions. Adaptations relevant to invasions are typically thought to occur either recently within the introduced range, as an evolutionary response to novel selection regimes, or within the native range, because of long-term adaptation to the local environment. We propose that recent adaptation within the native range, in particular adaptations to human-altered habitat, could also contribute to the evolution of invasive populations. Populations adapted to human-altered habitats in the native range are likely to increase in abundance within areas frequented by humans and associated with human transport mechanisms, thus enhancing the likelihood of transport to a novel range. Given that habitats are altered by humans in similar ways worldwide, as evidenced by global environmental homogenization, propagules from populations adapted to human-altered habitats in the native range should perform well within similarly human-altered habitats in the novel range. We label this scenario 'Anthropogenically Induced Adaptation to Invade'. We illustrate how it differs from other evolutionary processes that may occur during invasions, and how it can help explain accelerating rates of invasions.

Keywords: adaptation; agriculture; contemporary evolution; evolutionary theory; habitat degradation; invasive species.

Figure 1

Schematic representation of the AIAI scenario. (A) Within the natural habitats (in green) of the native range, local populations (blue hexagons) are exposed to human-altered habitat (in light orange). Some populations adapt to this new type of habitat becoming either generalists able to use both habitat types, or specialists on the human-altered habitat (orange and brown hexagon, respectively; see Box 2). Generalist populations are more likely to have substantial flow of movement and genes across habitat boundaries (dashed arrow). (B) Most long-distance transport happens between two human-altered habitats (hence the large arrows). The presence of adapted populations in the human-altered habitat of the native range results in increased transport probability and a diminished need for further adaptation in the human-altered habitat of the introduction range. In contrast, populations from natural habitats of the native range are expected to suffer both from rare introduction events and lack of necessary adaptations to start a population in the introduced range (red cross). C. The introduced populations are expected to invade rapidly, because of previous adaptation to a similar habitat. Generalist phenotypes may also further cross human-altered habitat boundaries (dashed arrow) without the additional adaptations needed by specialist phenotypes.