Assisted colonization as a climate change adaptation tool

Effective conservation planning of Iberian amphibians based on a regionalization of climate-driven range shifts

Amphibians are severely affected by climate change, particularly in regions where droughts prevail and water availability is scarce. The extirpation of amphibians triggers cascading effects that disrupt the trophic structure of food webs and ecosystems. Dedicated assessments of the spatial adaptive potential of amphibian species under climate change are, therefore, essential to provide guidelines for their effective conservation. I used predictions about the location of suitable climates for 27 amphibian species in the Iberian Peninsula from a baseline period to 2080 to typify shifting species' ranges. The time at which these range types are expected to be functionally important for the adaptation of a species was used to identify full or partial refugia; areas most likely to be the home of populations moving into new climatically suitable grounds; areas most likely to receive populations after climate adaptive dispersal; and climatically unsuitable areas near suitable areas. I implemented an area prioritization protocol for each species to obtain a cohesive set of areas that would provide maximum adaptability and where management interventions should be prioritized. A connectivity assessment pinpointed where facilitative strategies would be most effective. Each of the 27 species had distinct spatial requirements but, common to all species, a bottleneck effect was predicted by 2050 because source areas for subsequent dispersal were small in extent. Three species emerged as difficult to maintain up to 2080. The Iberian northwest was predicted to capture adaptive range for most species. My study offers analytical guidelines for managers and decision makers to undertake systematic assessments on where and when to intervene to maximize the persistence of amphibian species and the functionality of the ecosystems that depend on them.

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.

Genomic Approaches for Conservation Management in Australia under Climate Change

Conservation genetics has informed threatened species management for several decades. With the advent of advanced DNA sequencing technologies in recent years, it is now possible to monitor and manage threatened populations with even greater precision. Climate change presents a number of threats and challenges, but new genomics data and analytical approaches provide opportunities to identify critical evolutionary processes of relevance to genetic management under climate change. Here, we discuss the applications of such approaches for threatened species management in Australia in the context of climate change, identifying methods of facilitating viability and resilience in the face of extreme environmental stress. Using genomic approaches, conservation management practices such as translocation, targeted gene flow, and gene-editing can now be performed with the express intention of facilitating adaptation to current and projected climate change scenarios in vulnerable species, thus reducing extinction risk and ensuring the protection of our unique biodiversity for future generations. We discuss the current barriers to implementing conservation genomic projects and the efforts being made to overcome them, including communication between researchers and managers to improve the relevance and applicability of genomic studies. We present novel approaches for facilitating adaptive capacity and accelerating natural selection in species to encourage resilience in the face of climate change.

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.

Seasonal Variations of Faecal Cortisol Metabolites in Koalas in South East Queensland

The Koala (Phascolarctos cinereus) is an endemic marsupial inhabiting four states of Australia. Urbanisation, declining habitat, drought and fires are threatening the survival of this flagship species. These threats may cause acute and chronic stress in koalas, which might also be associated with occurrence of infectious diseases in koala populations. Stress may induce an increase in cortisol reflected in increased faecal cortisol metabolite (FCM) values. To be able to use faecal cortisol metabolites to measure stress levels in this species, our aim was to determine baseline values for males and females during breeding and non-breeding season. A total of 351 defecations were collected fortnightly, twice a day, for 12 months from koalas at a wildlife facility in South East Queensland. Samples were analysed with three different enzyme immunoassays (EIAs): a cortisol, 5α-pregnane-3β,11β,21-triol-20-one (37e) and tetrahydrocorticosterone (50c) EIA. The latter, which also reacts with tetrahydrocortisol, the main metabolite in koala faeces, was found to have the highest biological sensitivity and, therefore, is the most suitable EIA to measure stress levels in koalas. Utilising this EIA, we found significant differences (p < 0.05) in FCM values between males and females, breeding and non-breeding season, and between morning and evening samples. Values of faecal cortisol metabolites established in stress-free koalas in this study can serve as a reference for future studies in koalas.

Using ensemble modeling to predict the impacts of assisted migration on recipient ecosystems

Assisted migration is a controversial conservation measure that aims to protect threatened species by moving part of their population outside its natural range. Although this could save species from extinction, it also introduces a range of risks. The magnitude of the threat to recipient ecosystems has not been investigated quantitatively, despite being the most common criticism leveled at the action. We used an ensemble modeling framework to estimate the risks of assisted migration to existing species within ecosystems. With this approach, we calculated the consequences of an assisted migration project across a very large combination of translocated species and recipient ecosystems. We predicted the probability of a successful assisted migration and the number of local extinctions would result from establishment of the translocated species. Using an ensemble of 1.5×106 simulated 15-species recipient ecosystems, we estimated that translocated species will successfully establish in 83% of cases if introduced to stable, high-quality habitats. However, assisted migration projects were estimated to cause an average of 0.6 extinctions and 5% of successful translocations triggered 4 or more local extinctions. Quantifying the impacts to species within recipient ecosystems is critical to help managers weigh the benefits and negative consequences of assisted migration.

Conservation-oriented restoration - a two for one method to restore both threatened species and their habitats

There is an urgent need for a new conservation approach as mere designation of protected areas, the primary approach to conserving biodiversity, revealed its low conservation efficiency and inability to cope with numerous challenges faced by nature in the Anthropocene. The paper discusses the new concept, which proposes that ecological restoration becomes an integral part of conservation planning and implementation, and is done using threatened plant species that are introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. This new concept is called conservation-oriented restoration to distinguish it from the traditional restoration. Although the number of restoration projects focusing on recreation of once existing natural habitats is instantly growing, the majority of ecological restoration projects, in contrast to conservation-oriented restoration, have predominantly utilitarian goals, e.g. improvement or air quality, erosion control or soil replenishment. Conservation-oriented restoration should not be seen as an alternative either to the latter, or to the conservation dealing with particular threatened species (species-targeted conservation). These three conservation approaches, traditional ecological restoration, species-targeted conservation, and conservation-oriented restoration differ not only in broadly defined goals and attributes of their targets, but also in the types of ecosystems they are applicable to, and complement each other in combating global deterioration of the environment and biodiversity loss.

Uncertainty in ensembles of global biodiversity scenarios

While there is a clear demand for scenarios that provide alternative states in biodiversity with respect to future emissions, a thorough analysis and communication of the associated uncertainties is still missing. Here, we modelled the global distribution of ~11,500 amphibian, bird and mammal species and project their climatic suitability into the time horizon 2050 and 2070, while varying the input data used. By this, we explore the uncertainties originating from selecting species distribution models (SDMs), dispersal strategies, global circulation models (GCMs), and representative concentration pathways (RCPs). We demonstrate the overwhelming influence of SDMs and RCPs on future biodiversity projections, followed by dispersal strategies and GCMs. The relative importance of each component varies in space but also with the selected sensitivity metrics and with species’ range size. Overall, this means using multiple SDMs, RCPs, dispersal assumptions and GCMs is a necessity in any biodiversity scenario assessment, to explicitly report associated uncertainties.

Attaining global biodiversity projections requires the use of various species distribution and climate modelling and scenario approaches. Here the authors report that model choice can significantly impact results, with particularly uncertainty arising from choice of species distribution model and emission scenario.

Persistence of remnant patches and genetic loss at the distribution periphery in island and mainland populations of the quokka

Understanding the spatial structure of populations is important in developing effective management options for threatened species, and for managing habitat connectivity for metapopulation function, and for demographic and genetic heterogeneity. We used genetic information to investigate the structure of populations of the quokka, Setonix brachyurus, in south-west Western Australia. We hypothesised that movement between known populations would be relatively rare and result in significant genetic structuring. Genetic analyses from 412 adult individuals at 14 nuclear markers (microsatellite) from 33 sampling locations identified structure, diversity and spatial separation of quokkas across their mainland distribution and on two islands. We identified nine inferred (K = 9) populations of quokka that would be otherwise difficult to define with standard ecological techniques. The highest genetic diversity was evident in a large central population of quokka in the southern forest area and genetic diversity was lower at the peripheries of the distribution. The Rottnest Island population contained 70% of the genetic diversity of the mainland populations but the genetic diversity of animals on Bald Island was markedly lower. Populations of quokka in the northern jarrah forest were the only ones to show evidence of recent or long-term population bottlenecking. Of particular interest was the recently identified population at the Muddy Lakes area (the only remaining locality on the Swan Coastal Plain), which was identified as being genetically associated with the southern forest population. Overall, spatial and population cluster analysis showed small insular populations in the northern jarrah forest area, but in the southern forests there appears to be a large panmictic population.

Climate change risks, extinction debt, and conservation implications for a threatened freshwater fish: Carmine shiner (Notropis percobromus)

Climate change is affecting many freshwater species, particularly fishes. Predictions of future climate change suggest large and deleterious effects on species with narrow dispersal abilities due to limited hydrological connectivity. In turn, this creates the potential for population isolation in thermally unsuitable habitats, leading to physiological stress, species declines or possible extirpation. The current extent of many freshwater fish species' spatio-temporal distribution patterns and their sensitivity to thermal impacts from climate change - critical information for conservation planning - are often unknown. Carmine shiner (Notropis percobromus) is an ecologically important species listed as threatened or imperilled nationally (Canada) and regionally (South Dakota, United States) due to its restricted range and sensitivity to water quality and temperature. This research aimed to determine the current distribution and spatio-temporal variability in projected suitable habitat for Carmine shiner using niche-based modeling approaches (MaxEnt, BIOCLIM, and DOMAIN models). Statistically downscaled, bias-corrected Global Circulation Models (GCMs) data was used to model the distribution of Carmine shiner in central North America for the period of 2041-2060 (2050s). Maximum mean July temperature and temperature variability were the main factors in determining Carmine shiner distribution. Patterns of projected habitat change by the 2050s suggest the spatial extent of the current distribution of Carmine shiner would shift north, with >50% of the current distribution changing with future projections based on two Representative Concentrations Pathways for CO₂ emissions. Whereas the southern extent of the distribution would become unsuitable for Carmine shiner, suitable habitats are predicted to become available further north, if accessible. Importantly, the majority of habitat gains for Carmine shiner would be in areas currently inaccessible due to dispersal limitations, suggesting current populations may face an extinction debt within the next half century. These results provide evidence that Carmine shiner may be highly vulnerable to a warming climate and suggest that management actions - such as assisted migration - may be needed to mitigate impacts from climate change and ensure the long-term persistence of the species.

Plants adapted to warmer climate do not outperform regional plants during a natural heat wave

With ongoing climate change, many plant species may not be able to adapt rapidly enough, and some conservation experts are therefore considering to translocate warm‐adapted ecotypes to mitigate effects of climate warming. Although this strategy, called assisted migration, is intuitively plausible, most of the support comes from models, whereas experimental evidence is so far scarce. Here we present data on multiple ecotypes of six grassland species, which we grew in four common gardens in Germany during a natural heat wave, with temperatures 1.4–2.0°C higher than the long‐term means. In each garden we compared the performance of regional ecotypes with plants from a locality with long‐term summer temperatures similar to what the plants experienced during the summer heat wave. We found no difference in performance between regional and warm‐adapted plants in four of the six species. In two species, regional ecotypes even outperformed warm‐adapted plants, despite elevated temperatures, which suggests that translocating warm‐adapted ecotypes may not only lack the desired effect of increased performance but may even have negative consequences. Even if adaptation to climate plays a role, other factors involved in local adaptation, such as biotic interactions, may override it. Based on our results, we cannot advocate assisted migration as a universal tool to enhance the performance of local plant populations and communities during climate change.

Conservation in the face of climate change: recent developments

An increased understanding of the current and potential future impacts of climate change has significantly influenced conservation in practice in recent years. Climate change has necessitated a shift toward longer planning time horizons, moving baselines, and evolving conservation goals and targets. This shift has resulted in new perspectives on, and changes in, the basic approaches practitioners use to conserve biodiversity. Restoration, spatial planning and reserve selection, connectivity modelling, extinction risk assessment, and species translocations have all been reimagined in the face of climate change. Restoration is being conducted with a new acceptance of uncertainty and an understanding that goals will need to shift through time. New conservation targets, such as geophysical settings and climatic refugia, are being incorporated into conservation plans. Risk assessments have begun to consider the potentially synergistic impacts of climate change and other threats. Assisted colonization has gained acceptance in recent years as a viable and necessary conservation tool. This evolution has paralleled a larger trend in conservation—a shift toward conservation actions that benefit both people and nature. As we look forward, it is clear that more change is on the horizon. To protect biodiversity and essential ecosystem services, conservation will need to anticipate the human response to climate change and to focus not only on resistance and resilience but on transitions to new states and new ecosystems.