Coming to terms with the concept of moving species threatened by climate change - a systematic review of the terminology and definitions

Taming the terminological tempest in invasion science

Standardised terminology in science is important for clarity of interpretation and communication. In invasion science - a dynamic and rapidly evolving discipline - the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions. A standardised framework is therefore needed for a clear, universally applicable, and consistent terminology to promote more effective communication across researchers, stakeholders, and policymakers. Inconsistencies in terminology stem from the exponential increase in scientific publications on the patterns and processes of biological invasions authored by experts from various disciplines and countries since the 1990s, as well as publications by legislators and policymakers focusing on practical applications, regulations, and management of resources. Aligning and standardising terminology across stakeholders remains a challenge in invasion science. Here, we review and evaluate the multiple terms used in invasion science (e.g. 'non-native', 'alien', 'invasive' or 'invader', 'exotic', 'non-indigenous', 'naturalised', 'pest') to propose a more simplified and standardised terminology. The streamlined framework we propose and translate into 28 other languages is based on the terms (i) 'non-native', denoting species transported beyond their natural biogeographic range, (ii) 'established non-native', i.e. those non-native species that have established self-sustaining populations in their new location(s) in the wild, and (iii) 'invasive non-native' - populations of established non-native species that have recently spread or are spreading rapidly in their invaded range actively or passively with or without human mediation. We also highlight the importance of conceptualising 'spread' for classifying invasiveness and 'impact' for management. Finally, we propose a protocol for classifying populations based on (i) dispersal mechanism, (ii) species origin, (iii) population status, and (iv) impact. Collectively and without introducing new terminology, the framework that we present aims to facilitate effective communication and collaboration in invasion science and management of non-native species.

Projected future climatic forcing on the global distribution of vegetation types

Most emissions scenarios suggest temperature and precipitation regimes will change dramatically across the globe over the next 500 years. These changes will have large impacts on the biosphere, with species forced to migrate to follow their preferred environmental conditions, therefore moving and fragmenting ecosystems. However, most projections of the impacts of climate change only reach 2100, limiting our understanding of the temporal scope of climate impacts, and potentially impeding suitable adaptive action. To address this data gap, we model future climate change every 20 years from 2000 to 2500 CE, under different CO2 emissions scenarios, using a general circulation model. We then apply a biome model to these modelled climate futures, to investigate shifts in climatic forcing on vegetation worldwide, the feasibility of the migration required to enact these modelled vegetation changes, and potential overlap with human land use based on modern-day anthromes. Under a business-as-usual scenario, up to 40% of terrestrial area is expected to be suited to a different biome by 2500. Cold-adapted biomes, particularly boreal forest and dry tundra, are predicted to experience the greatest losses of suitable area. Without mitigation, these changes could have severe consequences both for global biodiversity and the provision of ecosystem services. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

The ethics of species extinctions

This review provides an overview of the ethics of extinctions with a focus on the Western analytical environmental ethics literature. It thereby gives special attention to the possible philosophical grounds for Michael Soulé's assertion that the untimely 'extinction of populations and species is bad'. Illustrating such debates in environmental ethics, the guiding question for this review concerns why - or when - anthropogenic extinctions are bad or wrong, which also includes the question of when that might not be the case (i.e. which extinctions are even desirable). After providing an explanation of the disciplinary perspective taken (section "Introduction"), the concept of extinction and its history within that literature are introduced (section "Understanding extinction"). Then, in section "Why (or when) might anthropogenic extinctions be morally problematic?", different reasons for why anthropogenic extinctions might be morally problematic are presented based on the loss of species' value, harm to nonhuman individuals, the loss of valuable biological variety and duties to future generations. This section concludes by also considering cases where anthropogenic extinctions might be justified. Section "How to respond to extinctions?" then addresses a selection of topics concerning risks and de-extinction technologies. Finally, the section on "Extinction studies" introduces other viewpoints on the ethics of extinction from the extinction studies literature, followed by the "Conclusion".

Facilitated Adaptation as A Conservation Tool in the Present Climate Change Context: A Methodological Guide

Climate change poses a novel threat to biodiversity that urgently requires the development of adequate conservation strategies. Living organisms respond to environmental change by migrating to locations where their ecological niche is preserved or by adapting to the new environment. While the first response has been used to develop, discuss and implement the strategy of assisted migration, facilitated adaptation is only beginning to be considered as a potential approach. Here, we present a review of the conceptual framework for facilitated adaptation, integrating advances and methodologies from different disciplines. Briefly, facilitated adaptation involves a population reinforcement that introduces beneficial alleles to enable the evolutionary adaptation of a focal population to pressing environmental conditions. To this purpose, we propose two methodological approaches. The first one (called pre-existing adaptation approach) is based on using pre-adapted genotypes existing in the focal population, in other populations, or even in closely related species. The second approach (called de novo adaptation approach) aims to generate new pre-adapted genotypes from the diversity present in the species through artificial selection. For each approach, we present a stage-by-stage procedure, with some techniques that can be used for its implementation. The associated risks and difficulties of each approach are also discussed.

Customary Norms, General Principles of International Environmental Law, and Assisted Migration as a Tool for Biodiversity Adaptation to Climate Change

Assisted migration (AM) is a translocation of the representatives of species to areas outside their natural habitats as a response to climate change. This article seeks to identify how customary norms and general principles of international environmental law could guide the development of regulation of AM maximizing the benefits of using AM and minimizing AM-related risks. Among the customary norms and principles of international environmental law discussed in the article and relevant to the regulation of AM are the permanent sovereignty over natural resources, the principle of cooperation, the no-harm rule, the precautionary principle, the principles of prevention, due diligence, and obligation to conduct environmental impact assessment (EIA), the principles of integration and intergenerational equity, common but differentiated responsibilities, and the polluter pays principle, the principles of non-regression, progression, resilience, in dubio pro natura, the principle of ecological proportionality, and the principle of access to information, public participation, and access to justice in environmental matters (principle of good governance, environmental democracy).

Current Conservation Regimes and the Road to Laws on Assisted Migration

The negative impact of climate change on biodiversity will continue to escalate rapidly. While some species will naturally migrate to more suitable areas or adapt to the new climatic environmental conditions in different fashions, for others doing so may prove to be problematic or impossible. Against this backdrop, scientists and environmentalists have proposed implementing plans for Assisted Migration (AM)-meaning the translocation of plants and animals to areas outside their natural habitats to conserve their species under the new emerging climatic conditions. This article seeks to identify legal approaches towards AM considering not only possible benefits from using this tool but also a necessity to minimize related risks. With regard to its stated purpose, this article also compares legal and policy documents relevant to AM issues from the United States, Australia, and the European Union. In conclusion, we have found, and this article shows, that while existing legal and policy documents leave room for manoeuvreing in regard to climate-related translocations and even sometimes explicitly mention AM as a possible tool for conservation, there exists a need for the further development of concrete legal mechanisms and their balancing with the predominant ideas and goals brought about by the necessity to protect native biota.

Landscape genomics of the streamside salamander: Implications for species management in the face of environmental change

Understanding spatial patterns of genetic differentiation and local adaptation is critical in a period of rapid environmental change. Climate change and anthropogenic development have led to population declines and shifting geographic distributions in numerous species. The streamside salamander, Ambystoma barbouri, is an endemic amphibian with a small geographic range that predominantly inhabits small, ephemeral streams. As A. barbouri is listed as near-threatened by the IUCN, we describe range-wide patterns of genetic differentiation and adaptation to assess the species' potential to respond to environmental change. We use outlier scans and genetic-environment association analyses to identify genomic variation putatively underlying local adaptation across the species' geographic range. We find evidence for adaptation with a polygenic architecture and a set of candidate SNPs that identify genes putatively contributing to local adaptation. Our results build on earlier work that suggests that some A. barbouri populations are locally adapted despite evidence for asymmetric gene flow between the range core and periphery. Taken together, the body of work describing the evolutionary genetics of range limits in A. barbouri suggests that the species may be unlikely to respond naturally to environmental challenges through a range shift or in situ adaptation. We suggest that management efforts such as assisted migration may be necessary in future.

Risks and opportunities of assisted colonization: the perspectives of experts

Owing to climate change and other anthropogenic environmental changes, the suitability of locations is changing for many biota that consequently have to adapt in situ or to move to other areas. To mitigate the effects of such pressures, assisted colonization is a conservation tool developed to reduce extinction risks by intentionally moving and releasing an organism outside its native range, and thus, to facilitate tracking changing environmental conditions. This conservation tool has been proposed for threatened animals or plants that presumably cannot adapt in situ or follow environmental changes by dispersal or migration. However, there have been contentious debates about the shortcomings and risks of implementing assisted colonization. For this reason, we evaluated the specific opinions of global experts for assisted colonization on potential risks and opportunities that this approach offers. For this purpose, we used an online survey targeted at authors of scientific publications on assisted colonization. The majority (82%) of the 48 respondents were in favor of applying assisted colonization for species that are at risk of global extinction due to anthropogenic environmental change. Most respondents agreed that assisted colonization should be considered only when other conservation tools are not available and that certain preconditions must be met. Some of these were already highlighted in the IUCN guidelines for assisted colonization and include a completed risk assessment, clearly defined management plans and secured political as well as financial support. The advocacy of assisted colonization in response to anthropogenic global environmental changes was only weakly dependent on the geographic origin of the experts and their working background. Regarding possible risks, most of the respondents were concerned about consequences like failure of the long-term establishment of the translocated species and the transmission of diseases and invasiveness potentially endangering native biota. To keep these risks as low as possible most of the experts agreed that a target area must have a reasonable carrying capacity to sustain a minimum viable population and that adaptive management should be implemented. Careful evaluation of assisted colonization projects is required to generate further evidence that needs to be considered for further developing conservation tools for the Anthropocene.

Embedding biodiversity research into climate adaptation policy and practice

Addressing climate change risks requires collaboration and engagement across all sectors of society. In particular, effective partnerships are needed between research scientists producing new knowledge, policy-makers and practitioners who apply conservation actions on the ground. We describe the implementation of a model for increasing the application and useability of biodiversity research in climate adaptation policy and practice. The focus of the program was to increase the ability of a state government agency and natural resource practitioners in Australia to manage and protect biodiversity in a changing climate. The model comprised a five-stage process for enhancing impact (i) initiation of research projects that addressed priority conservation policy and management issues; (ii) co-design of the research using a collaborative approach involving multiple stakeholders; (iii) implementation of the research and design of decision tools and web-based resources; (iv) collaborative dissemination of the tools and resources via government and community working groups; and (v) evaluation of research impact. We report on the model development and implementation, and critically reflect on the model's impact. We share the lessons learnt from the challenges of operating within a stakeholder group with diverse objectives and criteria for success, and provide a template for creating an environmental research program with real world impact.

Evaluating Assisted Gene Flow in Marginal Populations of a High Mountain Species

Many species cannot either migrate or adapt at the rate of temperature increases due to climate warming. Therefore, they need active conservation strategies to avoid extinction. Facilitated adaptation actions, such assisted gene flow, aim at the increase of the evolutionary resilience of species affected by global change. In elevational gradients, marginal populations at the lower elevation edges are experiencing earlier snowmelt and higher temperatures, which force them to adapt to the new conditions by modifying their phenology. In this context, advancing the onset of flowering and seed germination times are crucial to ensure reproductive success and increase seedling survival prior to summer drought. Assisted gene flow may bring adaptive alleles and increase genetic diversity that can help throughout ontogeny. The main aim of this work is to assess the effects that different gene flow treatments could have on the desired trait changes in marginal populations. Accordingly, we established a common garden experiment in which we assayed four different gene flow treatments between Silene ciliata Pourr. (Caryophyllaceae) populations located in similar and different elevation edges, belonging to the same and different mountains. As a control treatment, within-population crosses of low elevation edge populations were performed. The resulting seeds were sown and the germination and flowering onset dates of the resulting plants recorded, as well as the seedling survival. Gene flow between populations falling on the same mountain and same elevation and gene flow from high-elevation populations from a different mountain to low-elevation populations advanced seed germination time with respect to control crosses. No significant effects of gene flow on seedling survival were found. All the gene flow treatments delayed the onset of flowering with respect to control crosses and this effect was more pronounced in among-mountain gene flows. The results of this study highlight two important issues that should be thoroughly studied before attempting to apply assisted gene flow in practical conservation situations. Firstly, among-populations gene flow can trigger different responses in crucial traits throughout the ontogeny of plant species. Secondly, the population provenance of gene flow is determinant and plays a significant role on the effects of gene flow.

Importance of species translocations under rapid climate change

Species that cannot adapt or keep pace with a changing climate are likely to need human intervention to shift to more suitable climates. While hundreds of articles mention using translocation as a climate-change adaptation tool, in practice, assisted migration as a conservation action remains rare, especially for animals. This is likely due to concern over introducing species to places where they may become invasive. However, there are other barriers to consider, such as time-frame mismatch, sociopolitical, knowledge and uncertainty barriers to conservationists adopting assisted migration as a go-to strategy. We recommend the following to advance assisted migration as a conservation tool: attempt assisted migrations at small scales, translocate species with little invasion risk, adopt robust monitoring protocols that trigger an active response, and promote political and public support.

Translocation of an arctic seashore plant reveals signs of maladaptation to altered climatic conditions

Ongoing anthropogenic climate change alters the local climatic conditions to which species may be adapted. Information on species' climatic requirements and their intraspecific variation is necessary for predicting the effects of climate change on biodiversity. We used a climatic gradient to test whether populations of two allopatric varieties of an arctic seashore herb (Primula nutans ssp. finmarchica) show adaptation to their local climates and how a future warmer climate may affect them. Our experimental set-up combined a reciprocal translocation within the distribution range of the species with an experiment testing the performance of the sampled populations in warmer climatic conditions south of their range. We monitored survival, size, and flowering over four growing seasons as measures of performance and, thus, proxies of fitness. We found that both varieties performed better in experimental gardens towards the north. Interestingly, highest up in the north, the southern variety outperformed the northern one. Supported by weather data, this suggests that the climatic optima of both varieties have moved at least partly outside their current range. Further warming would make the current environments of both varieties even less suitable. We conclude that Primula nutans ssp. finmarchica is already suffering from adaptational lag due to climate change, and that further warming may increase this maladaptation, especially for the northern variety. The study also highlights that it is not sufficient to run only reciprocal translocation experiments. Climate change is already shifting the optimum conditions for many species and adaptation needs also to be tested outside the current range of the focal taxon in order to include both historic conditions and future conditions.

Addressing potential local adaptation in species distribution models: implications for conservation under climate change

Species distribution models (SDMs) have been criticized for involving assumptions that ignore or categorize many ecologically relevant factors such as dispersal ability and biotic interactions. Another potential source of model error is the assumption that species are ecologically uniform in their climatic tolerances across their range. Typically, SDMs treat a species as a single entity, although populations of many species differ due to local adaptation or other genetic differentiation. Not taking local adaptation into account may lead to incorrect range prediction and therefore misplaced conservation efforts. A constraint is that we often do not know the degree to which populations are locally adapted. Lacking experimental evidence, we still can evaluate niche differentiation within a species' range to promote better conservation decisions. We explore possible conservation implications of making type I or type II errors in this context. For each of two species, we construct three separate Max-Ent models, one considering the species as a single population and two of disjunct populations. Principal component analyses and response curves indicate different climate characteristics in the current environments of the populations. Model projections into future climates indicate minimal overlap between areas predicted to be climatically suitable by the whole species vs. population-based models. We present a workflow for addressing uncertainty surrounding local adaptation in SDM application and illustrate the value of conducting population-based models to compare with whole-species models. These comparisons might result in more cautious management actions when alternative range outcomes are considered.

Restoration, Reintroduction, and Rewilding in a Changing World

The increasing abandonment of marginal land creates new opportunities for restoration, reintroduction, and rewilding, but what do these terms mean in a rapidly and irreversibly changing world? The 're' prefix means 'back', but it is becoming clear that the traditional use of past ecosystems as targets and criteria for success must be replaced by an orientation towards an uncertain future. Current opinions in restoration and reintroduction biology range from a defense of traditional definitions, with some modifications, to acceptance of more radical responses, including assisted migration, taxon substitution, de-extinction, and genetic modification. Rewilding attempts to minimize sustained intervention, but this hands-off approach is also threatened by rapid environmental change.

Systematic Review of Methods in Low-Consensus Fields: Supporting Commensuration through `Construct-Centered Methods Aggregation' in the Case of Climate Change Vulnerability Research

There is increasing interest in using systematic review to synthesize evidence on the social and environmental effects of and adaptations to climate change. Use of systematic review for evidence in this field is complicated by the heterogeneity of methods used and by uneven reporting. In order to facilitate synthesis of results and design of subsequent research a method, construct-centered methods aggregation, was designed to 1) provide a transparent, valid and reliable description of research methods, 2) support comparability of primary studies and 3) contribute to a shared empirical basis for improving research practice. Rather than taking research reports at face value, research designs are reviewed through inductive analysis. This involves bottom-up identification of constructs, definitions and operationalizations; assessment of concepts' commensurability through comparison of definitions; identification of theoretical frameworks through patterns of construct use; and integration of transparently reported and valid operationalizations into ideal-type research frameworks. Through the integration of reliable bottom-up inductive coding from operationalizations and top-down coding driven from stated theory with expert interpretation, construct-centered methods aggregation enabled both resolution of heterogeneity within identically named constructs and merging of differently labeled but identical constructs. These two processes allowed transparent, rigorous and contextually sensitive synthesis of the research presented in an uneven set of reports undertaken in a heterogenous field. If adopted more broadly, construct-centered methods aggregation may contribute to the emergence of a valid, empirically-grounded description of methods used in primary research. These descriptions may function as a set of expectations that improves the transparency of reporting and as an evolving comprehensive framework that supports both interpretation of existing and design of future research.