Plant adaptation to climate change—Where are we?

Climate change poses critical challenges for population persistence in natural communities, for agriculture and environmental sustainability, and for food security. In this review, we discuss recent progress in climatic adaptation in plants. We evaluate whether climate change exerts novel selection and disrupts local adaptation, whether gene flow can facilitate adaptive responses to climate change, and whether adaptive phenotypic plasticity could sustain populations in the short term. Furthermore, we discuss how climate change influences species interactions. Through a more in‐depth understanding of these eco‐evolutionary dynamics, we will increase our capacity to predict the adaptive potential of plants under climate change. In addition, we review studies that dissect the genetic basis of plant adaptation to climate change. Finally, we highlight key research gaps, ranging from validating gene function to elucidating molecular mechanisms, expanding research systems from model species to other natural species, testing the fitness consequences of alleles in natural environments, and designing multifactorial studies that more closely reflect the complex and interactive effects of multiple climate change factors. By leveraging interdisciplinary tools (e.g., cutting‐edge omics toolkits, novel ecological strategies, newly developed genome editing technology), researchers can more accurately predict the probability that species can persist through this rapid and intense period of environmental change, as well as cultivate crops to withstand climate change, and conserve biodiversity in natural systems.     

Is adaptation to climate change really constrained in niche specialists?

Species with restricted distributions make up the vast majority of biodiversity. Recent evidence suggests that Drosophila species with restricted tropical distributions lack genetic variation in the key trait of desiccation resistance. It has therefore been predicted that tropically restricted species will be limited in their evolutionary response to future climatic changes and will face higher risks of extinction. However, these assessments have been made using extreme levels of desiccation stress (less than 10% relative humidity (RH)) that extend well beyond the changes projected for the wet tropics under climate change scenarios over the next 30 years. Here, we show that significant evolutionary responses to less extreme (35% RH) but more ecologically realistic levels of climatic change and desiccation stress are in fact possible in two species of rainforest restricted Drosophila. Evolution may indeed be an important means by which sensitive rainforest-restricted species are able to mitigate the effects of climate change.     

How is adaptation to climate change reflected in current practice of forest management and conservation? A case study from Germany

Climate change is expected to challenge forest management and nature conservation in forests. Besides forest species, strategies and references for management and conservation will be affected. In this paper, we qualitatively analysed whether forest conservation and management practice have already adapted to the impacts of climate change and to what extent those practices reflect the adaptation strategies dealt with in international peer-reviewed literature. To this end, we conducted thirteen in-depth interviews with forest practitioners (forest officers/forest district officers) in four regions in Germany. The interview regions were selected to represent the variation in tree species composition, forest ownership regimes and vulnerability to climate change. Although interviewees claimed to take climate change and adaptation strategies into account, in practice such strategies have as yet only occasionally been implemented. Our results suggest that strategies for adapting forest management to climate change are just in the early stages of development or supplement existing strategies relating to general risk reduction or nature-orientated forest management. The extent to which climate change adaptation strategies have influenced overall management varies. This variation and the lack of specific strategies also reflect the existing uncertainties about future changes in climate and about the capacity of forest ecosystems to adapt. We conclude that, in the face of climate change, forest management will have a major influence on future biodiversity composition of forest ecosystems. Hence, a framework for conservation in forests providing recommendations which also take into account the consequences of climate change needs to be developed.     

Would climate change drive species out of reserves? An assessment of existing reserve‐selection methods

Concern for climate change has not yet been integrated in protocols for reserve selection. However if climate changes as projected, there is a possibility that current reserve‐selection methods might provide solutions that are inadequate to ensure species' long‐term persistence within reserves. We assessed, for the first time, the ability of existing reserve‐selection methods to secure species in a climate‐change context. Six methods using a different combination of criteria (representation, suitability and reserve clustering) are compared. The assessment is carried out using European distributions of 1200 plant species and considering two extreme scenarios of response to climate change: no dispersal and universal dispersal. With our data, 6–11% of species modelled would be potentially lost from selected reserves in a 50‐year period. Measured uncertainties varied in 6% being 1–3% attributed to dispersal assumptions and 2–5% to the choice of reserve‐selection method. Suitability approaches to reserve selection performed best, while reserve clustering performed poorly. We also found that 5% of species modelled would lose their entire climatic envelope in the studied area; 2% of the species modelled would have nonoverlapping distributions; 93% of the species modelled would maintain varying levels of overlapping distributions. We conclude there are opportunities to minimize species' extinctions within reserves but new approaches are needed to account for impacts of climate change on species; especially for those projected to have temporally nonoverlapping distributions.     

Will pre‐adaptation buffer the impacts of climate change on novel species interactions?

Species are expected to alter their ranges as climates change. Climate‐induced range expansions of predators could threaten evolutionarily naïve prey populations, leading to high mortality at the invasion front. If prey can apply existing defenses against local predators to novel predation threats induced by climate change, mortality threats will be less than expected. Here, we examine if spotted salamander larvae Ambystoma maculatum from populations that coexist with native red‐spotted newts Notophthalmus viridescens survive better when exposed to a novel predator, the marbled salamander Ambystoma opacum. We show that regional mean winter temperatures warmed 2.0°C over 116 yr in the region, and that A. opacum survival increases in ponds with higher winter temperatures. Hence as winters continue to warm, this apex predator will likely colonize ponds north of their current range limit. Next, we performed common garden experiments to determine if local adaptations to native N. viridescens and exposure to A. opacum or N. viridescens kairomones (predator chemical cues) altered A. maculatum survival in predation trials. We did not find evidence for local adaptation to N. viridescens. However, A. maculatum from high‐N. viridescens ponds that were reared with A. opacum kairomones suffered significantly higher mortality from the native predator N. viridescens. This outcome suggests an unanticipated interaction between local adaptation and plastic responses to novel kairomones from a potentially range‐expanding predator. Current projections of biodiversity losses from climate change generally ignore the potential for eco‐evolutionary interactions between native and range‐expanding species and thus could be inaccurate.     

Is the life cycle of high arctic aphids adapted to climate change?

The high arctic aphid Acyrthosiphon svalbardicum Heikinheimo is endemic to Svalbard and has developed a shortened life cycle to cope with harsh environmental conditions prevailing in this archipelago. Previous studies in the 1990s showed that contrarily to Sitobion calvulum, a species which is also restricted to Svalbard and displays a two-generation life cycle, A. svalbardicum can produce a third generation that, on average, should complete its development and reproduction once every 28 years. Because temperature has risen substantially in Svalbard during the past 10 –15 years and is predicted to rise further, budget requirements for this extra-generation should be met more and more frequently and the impact of the resulting demographic increase should be easily measurable in field populations of A. svalbardicum. Here, we tested this hypothesis by performing a series of experiments designed to study population dynamics and morph production of A. svalbardicum. Surprisingly, the three-generation life cycle was not detected either in field populations surveyed for two consecutive years or in controlled conditions where temperature was manipulated. Although we cannot reject the possibility that A. svalbardicum populations may develop a three-generation life cycle under certain circumstances, this strategy seems very rare and not adaptive as it would have been selected in the recent years of warming observed in Svalbard.     

Can the acoustic adaptation hypothesis predict the structure of Australian birdsong?

The acoustic adaptation hypothesis (AAH) predicts that long-distance signals will be structured so as to maximize their transmission fidelity. Previous studies testing the hypothesis on birdsong have provided equivocal support. The best support comes from large-scale comparative studies and those studies where habitat is characterized as open versus densely vegetated. In the first case, sufficient statistical power is present to detect even small effects on song structure, whereas in the later case the effect size of the habitat may be sufficiently large. Most studies have focused on Holarctic or Neotropical species, which may ultimately share a common evolutionary history. In this study, Australian birds were chosen for a phylogenetically independent test of key predictions of the AAH. Specifically, birds in open habitats were predicted to sing songs with higher frequencies, greater bandwidth, have a greater probability of having overtones, and be emitted at a quicker rate than birds inhabiting densely forested habitats. Acoustic measurements were made on commercially available recordings of 121 species of Australian birds from 41 different families. Analyses controlled for variation explained by body mass (using ANCOVA), and phylogeny (using genus pairs analyses). We found only modest support for the AAH. Our finding that birds in open habitats produced higher frequency vocalizations and greater bandwidth vocalizations is also consistent with hypotheses about signal structure facilitating auditory distance assessment. Forest birds may therefore rely on cues other than frequency-dependent attenuation for ranging.     

What happens to the DNA vaccine in fish? A review of current knowledge

The primary function of DNA vaccines, a bacterial plasmid DNA containing a construct for a given protective antigen, is to establish specific and long-lasting protective immunity against diseases where conventional vaccines fail to induce protection. It is acknowledged that less effort has been made to study the fate, in terms of cellular uptake, persistence and degradation, of DNA vaccines after in vivo administration. However, during the last year some papers have given new insights into the fate of DNA vaccines in fish. By comparing the newly acquired information in fish with similar knowledge from studies in mammals, similarities with regard to transport, blood clearance, cellular uptake and degradation of DNA vaccines have been found. But the amount of DNA vaccine redistributed from the administration site after intramuscular administration seems to differ between fish and mammals. This review presents up-to-date and in-depth knowledge concerning the fate of DNA vaccines with emphasis on tissue distribution, cellular uptake and uptake mechanism(s) before finally describing the intracellular hurdles that DNA vaccines need to overcome in order to produce their gene product.     

Transboundary ecological networks as an adaptation strategy to climate change: The example of the Dutch – German border

Establishing ecological networks across national boundaries is essential for species to adapt to shifts in future suitable climate zones. This paper presents a method to assess whether the existing ecological network in the Dutch – German border region is “climate proof”. Using distribution data and climate envelope models for 846 species in Europe (mammals, birds, reptiles, amphibians and butterflies) we identified 216 species with climate-induced range shifts in the border region. A range expansion is predicted for 99 species and the ranges of 117 species are predicted to contract. The spatial cohesion of the ecological network was analysed for selected species that vary in habitat requirements and colonisation ability (forest species: Brenthis daphne, Dendrocopos medius; wetland species: Maculinea teleius, Lutra lutra). The assessment shows that optimising transboundary networks and developing corridors seems a suitable adaptation strategy for the forest species and for L. lutra. For the immobile butterfly M. teleius, the present habitat network is too weak and translocation into future suitable climate space seems to be a more appropriate adaptation measure. Our results underline that due to climate change landscape planning and management should not only focus on areas where target species occur today. The presented method can identify strongholds and bottlenecks in transboundary ecological networks and incorporate demands of climate adaptation into spatial planning which forms the basis for taking measures at a more detailed level.     

Can climate matching predict the current and future climatic suitability of the UK for the establishment of non-native birds?

Capsule: Current UK distributions of non-native birds poorly match areas identified as being climatically suitable.

Aims: Non-native species are spreading at unprecedented rates and though invasions are expected to increase under climate change, evidence for this is mixed. We assess climatic suitability throughout the UK based on the apparent match to the climate in species’ native ranges and investigate potential climatic limitation within the non-native range.

Methods: Climate was characterized within polygons representing the native ranges of 167 potentially invasive species. Parts of the UK with current and future climate similar to that in the native range were deemed climatically suitable. The incidence of recent observations inside and outside suitable areas was used to test hypotheses about climatic limitation of non-native ranges.

Results: Climate matching suggests that 69 of 167 non-native bird species could currently find climatically suitable areas for establishment in the UK. Future climate change would see this number increase by 14% by 2080. However, observed occurrences of non-native species in the UK were not significantly correlated to climatic suitability. Only 44 of the 69 species with suitable climate in the UK were present. Moreover, 85% of species observed in the UK had some UK occurrences in climatically unsuitable areas and for 57 species their entire UK range was in climatically unsuitable areas. Similar results were apparent for the subset of 12 species with established UK populations.

Conclusions: Climate matching provides a relatively poor indication of the extent of current and future suitable areas because species can adapt to new climates or other factors constrain the native range and many climatically suitable areas are currently unoccupied. Improvements to climate matching techniques and ongoing surveillance are required to refine predictions to support effective management policies.     

Back home? Uncertainties for returning seized animals to the source‐areas under climate change

Regardless of the economic, social and environmental impacts caused by wild animal trafficking worldwide, the suitable destination of seized specimens is one of the main challenges faced by environmental managers and authorities. In Brazil, returning seized animals to the wild has been the most frequent path in population restoration programs, and has been carried out, as a priority, in areas where the animals were captured. However, in addition to the difficulty in identifying the locations of illegal captures, little scientific knowledge is available on the future viability of the source‐areas to global climate change. Thus, the current work aims to evaluate the impacts of climate change on the main source‐municipalities for animal trafficking in Brazil, referred to herein as source‐areas. For this, using ecological niche modeling, the environmental suitability of the source‐areas for illegal animal captures was evaluated in two scenarios at two different time horizons: optimistic (RCP 26) and pessimistic (RCP 85) emission scenarios in both 2050 and 2070 projections. Moreover, the source‐areas were compared with the Brazilian Federal protected areas, used here as the control group. According to the results, Brazilian source‐municipalities are not always the best option for maintaining the most seized species in the future simulations, and, therefore, seem not be the best option for projects that aim for the return of these animals to the wild. In this sense, despite the genetic and ecological issues inherent in translocation projects, our results suggest that population restoration programs for seized species need to be rethought, and furthermore other suitable areas could be considered for truly ensuring the survival and maintenance of overexploited populations in the long term.     

Must top predators be culled for the sake of fisheries?

If humankind occupies the ecological role of top predator, then within individual ecosystems it must compete with other top predators for valuable food resources. This notion presents a fascinating ecological problem, with tremendous social and economic ramifications. Because of the socioeconomic dimension, the scientific debate has at times been controversial. The recent attention and data gathering resources focused on the problem present a unique opportunity to test and refine ecological theory in the arena of complex, large-scale systems.     

Multispecies comparisons of adaptability to climate change: A role for life‐history characteristics?

Phenological advancement allows individuals to adapt to climate change by timing life‐history events to the availability of key resources so that individual fitness is maximized. However, different trophic levels may respond to changes in their environment at different rates, potentially leading to a phenological mismatch. This may be especially apparent in the highly seasonal arctic environment that is experiencing the effects of climate change more so than any other region. During a 14‐year study near Utqia?vik (formerly Barrow), Alaska, we estimated phenological advancement in egg laying in relation to snowmelt for eight arctic‐breeding shorebirds and investigated potential linkages to species‐specific life‐history characteristics. We found that snowmelt advanced 0.8 days/year—six times faster than the prior 60‐year period. During this same time, six of the eight species exhibited phenological advancement in laying dates (varying among species from 0.1 to 0.9 days earlier per year), although no species appeared capable of keeping pace with advancing snowmelt. Phenological changes were likely the result of high phenotypic plasticity, as all species investigated in this study showed high interannual variability in lay dates. Commonality among species with similar response rates to timing of snowmelt suggests that nesting later and having an opportunistic settlement strategy may increase the adaptability of some species to changing climate conditions. Other life‐history characteristics, such as migration strategy, previous site experience, and mate fidelity did not influence the ability of individuals to advance laying dates. As a failure to advance egg laying is likely to result in greater phenological mismatch, our study provides an initial assessment of the relative risk of species to long‐term climatic changes.     

Can terrestrial ectotherms escape the heat of climate change by moving?

Whether movement will enable organisms to alleviate thermal stress is central to the biodiversity implications of climate change. We use the temperature-dependence of ectotherm performance to investigate the fitness consequences of movement. Movement to an optimal location within a 50 km radius will only offset the fitness impacts of climate change by 2100 in 5 per cent of locations globally. Random movement carries an 87 per cent risk of further fitness detriment. Mountainous regions with high temperature seasonality (i.e. temperate areas) not only offer the greatest benefit from optimal movement but also the most severe fitness consequences if an organism moves to the wrong location. Doubling dispersal capacity would provide modest benefit exclusively to directed dispersers in topographically diverse areas. The benefits of movement for escaping climate change are particularly limited in the tropics, where fitness impacts will be most severe. The potential of movement to lessen climate change impacts may have been overestimated.     

Can adherence to dietary guidelines address excess caloric intake? An empirical assessment for the UK

The facilitation of healthier dietary choices by consumers is a key element of government strategies to combat the rising incidence of obesity in developed and developing countries. Public health campaigns to promote healthier eating often target compliance with recommended dietary guidelines for consumption of individual nutrients such as fats and added sugars. This paper examines the association between improved compliance with dietary guidelines for individual nutrients and excess calorie intake, the most proximate determinant of obesity risk. We apply quantile regressions and counterfactual decompositions to cross-sectional data from the National Diet and Nutrition Survey (2000–01) to assess how excess calorie consumption patterns in the UK are likely to change with improved compliance with dietary guidelines. We find that the effects of compliance vary significantly across different quantiles of calorie consumption. Our results show that compliance with dietary guidelines for individual nutrients, even if successfully achieved, is likely to be associated with only modest shifts in excess calorie consumption patterns. Consequently, public health campaigns that target compliance with dietary guidelines for specific nutrients in isolation are unlikely to have a significant effect on the obesity risk faced by the population.