Professor University of California, Santa Cruz Santa Cruz, California, United States
Abstract: Invasive species are widely accepted as a cause of ecosystem degradation and threaten species with extinction, yet their management and perception within scientific and public discourse are debated. Much of this debate can be clarified by considering the larger historical processes shaping biological invasions, particularly European colonization. We situate invasive species within the ongoing history of settler colonialism that shapes and dominates many ecosystems globally. We reviewed studies that associate invasive species and their interactions with each other and with native species with the historical process of European colonization. We reviewed historical evidence of introductions of nonnative species since 1492 in the ecological and social scientific literature. We also incorporated works from environmental sociology, settler colonial and Indigenous studies, and historical literature to explain what settler colonialism entails socially and ecologically. We asked how settler colonialism creates the conditions for biological invasions and what roles invasive species play in facilitating settler colonialism around the world. We drew on case studies and reviews of biological invasions to propose the concept of collaborative colonization, which extends previous ideas about mutualisms between co-occurring nonnative species to mutual facilitation of and positive feedbacks between biological invasions and settler colonialism. Here, we discuss three cases that illustrate positive feedback loops between biological invasions and European settler colonialism. First, we illustrate how settler colonialism can create the conditions for invasive species to outcompete native ones that are not inherently inferior competitors. This is demonstrated by common garden experiments in which exotic annual grasses outcompete perennial native grasses that otherwise are able to compete effectively against the invaders when nonnative livestock are present. Second, we discuss how species introductions of microbes, plants, and animals have in many instances reduced Indigenous peoples’ ability to resist colonization. For example, rats, feral pigs, and pathogens helped undermine Indigenous resistance to colonization by disrupting Indigenous food sources and weakening populations. Finally, we discuss how some species, like introduced earthworms, enabled invasion by other species and supported European agricultural crops, illustrating the “collaborative” nature of biological invasions during settler colonization. In this light, restorating invaded systems in the face of settler colonialism’s social and ecological impacts is not as simple as removing nonnative species but also must include considerations of human history and of Indigenous sovereignty. We urge fellow ecologists studying biological invasions to take an expansive understanding of the ecological impacts of settler colonialism and to address them in our research.
