Effect of planting date on flowering time in wheat

The time from seed germination to anthesis varied for spring wheat in experiments in climate chambers with plants grown hydroponically at different nitrogen regimes. Time to anthesis was related to the time of seed germination during the calendar year. Seed germinating earlier in the calendar year required a shorter time to anthesis compared to seed germinating later in the year, a pattern found for all the spring wheat cultivars investigated. Time to anthesis was also found to be independent of factors such as year in which the seed was produced, nitrogen regime used, or year or site of cultivation. We suggest the existence of an annual rhythm for flowering in spring wheat. This variation in time to flowering can be due either to external factors or more likely to an endogenous rhythm in the plant. When investigating plant processes, it is of importance to be aware of such a rhythm, since it may influence the results depending on when during the year the experiments are performed.     

Adaptation to climate through flowering phenology: a case study in Medicago truncatula

Local climatic conditions likely constitute an important selective pressure on genes underlying important fitness‐related traits such as flowering time, and in many species, flowering phenology and climatic gradients strongly covary. To test whether climate shapes the genetic variation on flowering time genes and to identify candidate flowering genes involved in the adaptation to environmental heterogeneity, we used a large Medicago truncatula core collection to examine the association between nucleotide polymorphisms at 224 candidate genes and both climate variables and flowering phenotypes. Unlike genome‐wide studies, candidate gene approaches are expected to enrich for the number of meaningful trait associations because they specifically target genes that are known to affect the trait of interest. We found that flowering time mediates adaptation to climatic conditions mainly by variation at genes located upstream in the flowering pathways, close to the environmental stimuli. Variables related to the annual precipitation regime reflected selective constraints on flowering time genes better than the other variables tested (temperature, altitude, latitude or longitude). By comparing phenotype and climate associations, we identified 12 flowering genes as the most promising candidates responsible for phenological adaptation to climate. Four of these genes were located in the known flowering time QTL region on chromosome 7. However, climate and flowering associations also highlighted largely distinct gene sets, suggesting different genetic architectures for adaptation to climate and flowering onset.     

Quantifying variety‐specific heat resistance and the potential for adaptation to climate change

The impact of climate change on crop yields has become widely measured; however, the linkages for winter wheat are less studied due to dramatic weather changes during the long growing season that are difficult to model. Recent research suggests significant reductions under warming. A potential adaptation strategy involves the development of heat resistant varieties by breeders, combined with alternative variety selection by producers. However, the impact of heat on specific wheat varieties remains relatively unstudied due to limited data and the complex genetic basis of heat tolerance. Here, we provide a novel econometric approach that combines field‐trial data with a genetic cluster mapping to group wheat varieties and estimate a separate extreme heat impact (temperatures over 34 °C) across 24 clusters spanning 197 varieties. We find a wide range of heterogeneous heat resistance and a trade‐off between average yield and resistance. Results suggest that recently released varieties are less heat resistant than older varieties, a pattern that also holds for on‐farm varieties. Currently released – but not yet adopted – varieties do not offer improved resistance relative to varieties currently grown on farm. Our findings suggest that warming impacts could be significantly reduced through advances in wheat breeding and/or adoption decisions by producers. However, current adaptation‐through‐adoption potential is limited under a 1 °C warming scenario as increased heat resistance cannot be achieved without a reduction in average yields.     

Single rice growth period was prolonged by cultivars shifts,but yield was damaged by climate change during 1981–2009 in China,and late rice was just opposite

Based on the crop trial data during 1981–2009 at 57 agricultural experimental stations across the North Eastern China Plain (NECP) and the middle and lower reaches of Yangtze River (MLRYR), we investigated how major climate variables had changed and how the climate change had affected crop growth and yield in a setting in which agronomic management practices were taken based on actual weather. We found a significant warming trend during rice growing season, and a general decreasing trend in solar radiation (SRD) in the MLRYR during 1981–2009. Rice transplanting, heading, and maturity dates were generally advanced, but the heading and maturity dates of single rice in the MLRYR (YZ_SR) and NECP (NE_SR) were delayed. Climate warming had a negative impact on growth period lengths at about 80% of the investigated stations. Nevertheless, the actual growth period lengths of YZ_SR and NE_SR, as well as the actual length of reproductive growth period (RGP) of early rice in the MLRYR (YZ_ER), were generally prolonged due to adoption of cultivars with longer growth period to obtain higher yield. In contrast, the actual growth period length of late rice in the MLRYR (YZ_LR) was shortened by both climate warming and adoption of early mature cultivars to prevent cold damage and obtain higher yield. During 1981–2009, climate warming and decrease in SRD changed the yield of YZ_ER by ?0.59 to 2.4%; climate warming during RGP increased the yield of YZ_LR by 8.38–9.56%; climate warming and decrease in SRD jointly reduced yield of YZ_SR by 7.14–9.68%; climate warming and increase in SRD jointly increased the yield of NE_SR by 1.01–3.29%. Our study suggests that rice production in China has been affected by climate change, yet at the same time changes in varieties continue to be the major factor driving yield and growing period trends.     

Tree range expansion in eastern North America fails to keep pace with climate warming at northern range limits

Rising global temperatures are suggested to be drivers of shifts in tree species ranges. The resulting changes in community composition may negatively impact forest ecosystem function. However, long‐term shifts in tree species ranges remain poorly documented. We test for shifts in the northern range limits of 16 temperate tree species in Quebec, Canada, using forest inventory data spanning three decades, 15° of longitude and 7° of latitude. Range shifts were correlated with climate warming and dispersal traits to understand potential mechanisms underlying changes. Shifts were calculated as the change in the 95th percentile of latitudinal occurrence between two inventory periods (1970–1978, 2000–2012) and for two life stages: saplings and adults. We also examined sapling and adult range offsets within each inventory, and changes in the offset through time. Tree species ranges shifted predominantly northward, although species responses varied. As expected shifts were greater for tree saplings, 0.34 km yr^?1, than for adults, 0.13 km yr^?1. Range limits were generally further north for adults compared to saplings, but the difference diminished through time, consistent with patterns observed for range shifts within each life stage. This suggests caution should be exercised when interpreting geographic range offsets between life stages as evidence of range shifts in the absence of temporal data. Species latitudinal velocities were on average <50% of the velocity required to equal the spatial velocity of climate change and were mostly unrelated to dispersal traits. Finally, our results add to the body of evidence suggesting tree species are mostly limited in their capacity to track climate warming, supporting concerns that warming will negatively impact the functioning of forest ecosystems.     

Of mast and mean: differential‐temperature cue makes mast seeding insensitive to climate change

Mast‐seeding plants often produce high seed crops the year after a warm spring or summer, but the warm‐temperature model has inconsistent predictive ability. Here, we show for 26 long‐term data sets from five plant families that the temperature difference between the two previous summers (ΔT) better predicts seed crops. This discovery explains how masting species tailor their flowering patterns to sites across altitudinal temperature gradients; predicts that masting will be unaffected by increasing mean temperatures under climate change; improves prediction of impacts on seed consumers; demonstrates that strongly masting species are hypersensitive to climate; explains the rarity of consecutive high‐seed years without invoking resource constraints; and generates hypotheses about physiological mechanisms in plants and insect seed predators. For plants, ΔT has many attributes of an ideal cue. This temperature‐difference model clarifies our understanding of mast seeding under environmental change, and could also be applied to other cues, such as rainfall.     

Dryness limits vegetation pace to cope with temperature change in warm regions

Climate change leads to increasing temperature and more extreme hot and drought events. Ecosystem capability to cope with climate warming depends on vegetation's adjusting pace with temperature change. How environmental stresses impair such a vegetation pace has not been carefully investigated. Here we show that dryness substantially dampens vegetation pace in warm regions to adjust the optimal temperature of gross primary production (GPP) ($T_{\mathrm{opt}}^{\mathrm{GPP}}$) in response to change in temperature over space and time. $T_{\mathrm{opt}}^{\mathrm{GPP}}$ spatially converges to an increase of 1.01°C (95% CI: 0.97, 1.05) per 1°C increase in the yearly maximum temperature (T_max) across humid or cold sites worldwide (37^oS–79^oN) but only 0.59°C (95% CI: 0.46, 0.74) per 1°C increase in T_max across dry and warm sites. $T_{\mathrm{opt}}^{\mathrm{GPP}}$ temporally changes by 0.81°C (95% CI: 0.75, 0.87) per 1°C interannual variation in T_max at humid or cold sites and 0.42°C (95% CI: 0.17, 0.66) at dry and warm sites. Regardless of the water limitation, the maximum GPP (GPP_max) similarly increases by 0.23 g C m⁻² day⁻¹ per 1°C increase in $T_{\mathrm{opt}}^{\mathrm{GPP}}$ in either humid or dry areas. Our results indicate that the future climate warming likely stimulates vegetation productivity more substantially in humid than water-limited regions.     

Asynchronous flowering and within-plant flowering diversity in wheat and the implications for crop resilience to heat

Background and Aims

Self-pollination dominates in wheat, with a small level of out-crossing due to flowering asynchrony and male sterility. However, the timing and synchrony of male and female flowering in wheat is a crucial determinant of seed set and may be an important factor affecting gene flow and resilience to climate change. Here, a methodology is presented for assessing the timing and synchrony of flowering in wheat, Triticum aestivum.

Methods

From the onset of flowering until the end of anthesis, the anther and stigma activity of each floret was assessed on the first five developing ears in potted plants grown under ambient conditions and originating from ‘Paragon’ or ‘Spark-Rialto’ backgrounds. At harvest maturity, seed presence, size and weight was recorded for each floret scored.

Key Results and Conclusions

The synchrony between pollen dehiscence and stigma collapse within a flower was dependent on its relative position in a spike and within a floret. Determined on the basis of synchrony within each flower, the level of pollination by pollen originating from other flowers reached approx. 30 % and did not change throughout the duration of flowering. A modelling exercise parameterized by flowering observations indicated that the temporal and spatial variability of anther activity within and between spikes may influence the relative resilience of wheat to sudden, extreme climatic events which has direct relevance to predicted future climate scenarios in the UK.     

A 250-year index of first flowering dates and its response to temperature changes

Widespread concerns about global biodiversity loss have led to a growing demand for indices of biodiversity status. Today, climate change is among the most serious threats to global biodiversity. Although many studies have revealed phenological responses to climate change, no long-term community-level indices have been developed. We derived a 250-year index of first flowering dates for 405 plant species in the UK for assessing the impact of climate change on plant communities. The estimated community-level index in the most recent 25 years was 2.2–12.7 days earlier than any other consecutive 25-year period since 1760. The index was closely correlated with February–April mean Central England Temperature, with flowering 5.0 days earlier for every 1°C increase in temperature. The index was relatively sensitive to the number of species, not records per species, included in the model. Our results demonstrate how multi-species, multiple-site phenological events can be integrated to obtain indices showing trends for each species and across species. This index should play an important role in monitoring the impact of climate change on biodiversity. Furthermore, this approach can be extended to incorporate data from other taxa and countries for evaluating cross-taxa and cross-country phenological responses to climate change.     

亚热带植物春季和秋季物候格局及其对气候变化的响应

全球变暖导致的物候变化已经对生物多样性和生态系统产生了重要影响,与温带和寒带相比,亚热带物候学的研究相对较少,秋季物候的研究也十分缺乏,不同功能群植物的物候对气候变化的响应是否存在差别,都有待进一步研究。为了研究亚热带植物春季和秋季物候对气候变化的响应以及不同功能群间的差异性,该研究利用湖南省长沙植物园25种木本植物20 a的物候观测数据,根据AIC信息标准,先筛选各物种最佳温度和降水模型,并利用Wilcoxon秩和检验分析不同功能群的物种对温度的响应是否一致。结果表明:(1)大多数物种的春季物候和秋季物候都对温度变化响应显著,展叶与开花的提前速率分别是3.76 d·℃^-1和6.53 d·℃^-1,叶变色与落叶的推迟速率分别是16.66 d·℃^-1和3.50 d·℃^-1。(2)部分物种的春季(展叶物候:60%,开花物候:35%)和秋季(叶变色物候:25%,落叶物候:13%)对降水显著响应。(3)除不同落叶性物种(常绿和落叶之间)的展叶物候表现出对气候的响应有显著差异外,其他不同功能群的物种对气候的响应均无显著差异。该研究认为,亚热带地区植物春季物候显著提前,秋季物候显著推迟,且亚热带地区不同功能群的物种对温度的响应大部分无显著差异,表明气候变化对亚热带地区不同功能群的影响程度大部分趋同。     

Adapting to winter in wheat: a long-term study follows parallel phenotypic and genetic changes in three experimental wheat populations

Drawing a direct connection between adaptive evolution at the phenotypic level and underlying genetic factors has long been a major goal of evolutionary biologists, but the genetic characterization of adaptive traits in natural populations is notoriously difficult. The study of evolution in experimental populations offers some help — initial conditions are known and changes can be tracked for extended periods under conditions more controlled than wild populations and more realistic than laboratory or greenhouse experiments. In this issue of Molecular Ecology , researchers studying experimental wheat populations over a 12-year period have demonstrated evolution in a major adaptive trait, flowering time, and parallel changes in underlying genetic variation ( Rhoné et al . 2008 ). Their work suggests that cis -regulatory mutations at a single gene may explain most of the flowering time variation in these populations.     

Modelling changes in species’ abundance in response to projected climate change

Aim Existing climate envelope models give an indication of broad scale shifts in distribution, but do not specifically provide information on likely future population changes useful for conservation prioritization and planning. We demonstrate how these techniques can be developed to model likely future changes in absolute density and population size as a result of climate change. Location Great Britain. Methods Generalized linear models were used to model breeding densities of two northerly‐ and two southerly‐distributed bird species as a function of climate and land use. Models were built using count data from extensive national bird monitoring data and incorporated detectability to estimate absolute abundance. Projections of likely future changes in the distribution and abundance of these species were made by applying these models to projections of future climate change under two emissions scenarios. Results Models described current spatial variation in abundance for three of the four species and produced modelled current estimates of national populations that were similar to previously published estimates for all species. Climate change was projected to result in national population declines in the two northerly‐distributed species, with declines for Eurasian curlew Numenius arquata projected to be particularly severe. Conversely, the abundances of the two southerly distributed species were projected to increase nationally. Projected maps of future abundance may be used to identify priority areas for the future conservation of each species. Main conclusions The analytical methods provide a framework to make projections of impacts of climate change on species abundance, rather than simply projected range changes. Outputs may be summarized at any spatial scale, providing information to inform future conservation planning at national, regional and local scales. Results suggest that as a consequence of climate change, northerly distributed bird species in Great Britain are likely to become an increasingly high conservation priority within the UK.     

The rhythmic expression of genes controlling flowering time in southern and northern populations of invasive Ambrosia artemisiifolia

Aims Flowering time has been suggested to be an important adaptive trait during the dispersal of invasive species, and identifying the molecular mechanisms underlying flowering time may provide insight into the local adaptation during the process of invasion. Here, we conducted a preliminary exploration on the genetic basis of the differentiation of flowering time in Ambrosia artemisiifolia .Methods Using relative real-time fluorescent quantitative polymerase chain reaction, we investigated the expression levels of eight flowering-related genes, including AP1, FT, SOC1, CRY2, FKF1, GI, CO2 and SPY, in leaves and flowers at different time points in individuals from northern Beijing and southern Wuhan populations that exhibit significant differences in flowering times to identify any rhythmic changes in gene expression and their association with differential flowering times.Important findings The differentiation of flowering time in the A. artemisiifolia populations was closely associated with five genes involved in flowering pathways. The floral pathway integrators FT and SOC1 and floral meristem identity gene AP1 exhibited increased expression during flowering. The photoreceptor CRY2 in the light-dependent pathway and the SPY gene in the gibberellin pathway displayed specific expression patterns over time. In earlier-flowering Beijing plants, CRY2 expression was lower and SPY expression was higher than in Wuhan plants. The expression patterns of these five genes suggest a molecular basis for the differentiation of flowering time in A. artemisiifolia .     

A 120‐year record of resilience to environmental change in brachiopods

The inability of organisms to cope in changing environments poses a major threat to their survival. Rising carbon dioxide concentrations, recently exceeding 400 μatm, are rapidly warming and acidifying our oceans. Current understanding of organism responses to this environmental phenomenon is based mainly on relatively short‐ to medium‐term laboratory and field experiments, which cannot evaluate the potential for long‐term acclimation and adaptation, the processes identified as most important to confer resistance. Here, we present data from a novel approach that assesses responses over a centennial timescale showing remarkable resilience to change in a species predicted to be vulnerable. Utilising museum collections allows the assessment of how organisms have coped with past environmental change. It also provides a historical reference for future climate change responses. We evaluated a unique specimen collection of a single species of brachiopod (Calloria inconspicua) collected every decade from 1900 to 2014 from one sampling site. The majority of brachiopod shell characteristics remained unchanged over the past century. One response, however, appears to reinforce their shell by constructing narrower punctae (shell perforations) and laying down more shell. This study indicates one of the most calcium‐carbonate‐dependent species globally to be highly resilient to environmental change over the last 120 years and provides a new insight for how similar species might react and possibly adapt to future change.     

Prediction of near-term climate change impacts on UK wheat quality and the potential for adaptation through plant breeding

Wheat is a major crop worldwide, mainly cultivated for human consumption and animal feed. Grain quality is paramount in determining its value and downstream use. While we know that climate change threatens global crop yields, a better understanding of impacts on wheat end-use quality is also critical. Combining quantitative genetics with climate model outputs, we investigated UK-wide trends in genotypic adaptation for wheat quality traits. In our approach, we augmented genomic prediction models with environmental characterisation of field trials to predict trait values and climate effects in historical field trial data between 2001 and 2020. Addition of environmental covariates, such as temperature and rainfall, successfully enabled prediction of genotype by environment interactions (G × E), and increased prediction accuracy of most traits for new genotypes in new year cross validation. We then extended predictions from these models to much larger numbers of simulated environments using climate scenarios projected under Representative Concentration Pathways 8.5 for 2050–2069. We found geographically varying climate change impacts on wheat quality due to contrasting associations between specific weather covariables and quality traits across the UK. Notably, negative impacts on quality traits were predicted in the East of the UK due to increased summer temperatures while the climate in the North and South-west may become more favourable with increased summer temperatures. Furthermore, by projecting 167,040 simulated future genotype–environment combinations, we found only limited potential for breeding to exploit predictable G × E to mitigate year-to-year environmental variability for most traits except Hagberg falling number. This suggests low adaptability of current UK wheat germplasm across future UK climates. More generally, approaches demonstrated here will be critical to enable adaptation of global crops to near-term climate change.     

Stream isotherm shifts from climate change and implications for distributions of ectothermic organisms

Stream ecosystems are especially vulnerable to climate warming because most aquatic organisms are ectothermic and live in dendritic networks that are easily fragmented. Many bioclimatic models predict significant range contractions in stream biotas, but subsequent biological assessments have rarely been done to determine the accuracy of these predictions. Assessments are difficult because model predictions are either untestable or so imprecise that definitive answers may not be obtained within timespans relevant for effective conservation. Here, we develop the equations for calculating isotherm shift rates (ISRs) in streams that can be used to represent historic or future warming scenarios and be calibrated to individual streams using local measurements of stream temperature and slope. A set of reference equations and formulas are provided for application to most streams. Example calculations for streams with lapse rates of 0.8 °C/100 m and long‐term warming rates of 0.1–0.2 °C decade^?1 indicate that isotherms shift upstream at 0.13–1.3 km decade^?1 in steep streams (2–10% slope) and 1.3–25 km decade^?1 in flat streams (0.1–1% slope). Used more generally with global scenarios, the equations predict isotherms shifted 1.5–43 km in many streams during the 20th Century as air temperatures increased by 0.6 °C and would shift another 5–143 km in the first half of the 21st Century if midrange projections of a 2 °C air temperature increase occur. Variability analysis suggests that short‐term variation associated with interannual stream temperature changes will mask long‐term isotherm shifts for several decades in most locations, so extended biological monitoring efforts are required to document anticipated distribution shifts. Resampling of historical sites could yield estimates of biological responses in the short term and should be prioritized to validate bioclimatic models and develop a better understanding about the effects of temperature increases on stream biotas.     

Acclimation of photosynthesis to temperature in eight cool and warm climate herbaceous C3 species: Temperature dependence of parameters of a biochemical photosynthesis model

To determine how parameters of a Farquhar-type photosynthesis model varied with measurement temperature and with growth temperature, eight cool and warm climate herbaceous crop and weed species were grown at 15 and 25 °C and single leaf carbon dioxide and water vapor exchange rates were measured over the range of 15 – 35 °C. Photosynthetic parameters examined were the initial slope of the response of assimilation rate (A) to substomatal carbon dioxide concentration (C_i), A at high C_i, and stomatal conductance. The first two measurements allow calculation of V_Cmax, the maximum rate of carboxylation of ribulose bisphosphate carboxylase and J_max, the maximum rate of photosynthetic electron transport, of Farquhar-type photosynthesis models. In all species, stomatal conductance increased exponentially with temperature over the whole range of 15 – 35 °C, even when A decreased at high measurement temperature. There were larger increases in conductance over this temperature range in the warm climate species (4.3 ×) than in the cool climate species (2.5 ×). The initial slope of A vs. C_i exhibited an optimum temperature which ranged from 20 to 30 °C. There was a larger increase in the optimum temperature of the initial slope at the warmer growth temperature in the cool climate species than in the warm climate species. The optimum temperature for A at high C_i ranged from 25 to 30 °C among species, but changed little with growth temperature. The absolute values of both the initial slope of A vs. C_i and A at high C_i were increased about 10% by growth at the warmer temperature in the warm climate species, and decreased about 20% in the cool climate species. The ratio of J_max — V_Cmax normalized to 20 °C varied by more than a factor of 2 across species and growth temperatures, but differences in the temperature response of photosynthesis were more related to variation in the temperature dependencies of J_max and V_Cmax than to the ratio of their normalized values.This revised version was published online in October 2005 with corrections to the Cover Date.     

Susceptibility of European freshwater fish to climate change: Species profiling based on life‐history and environmental characteristics

Climate change is expected to strongly affect freshwater fish communities. Combined with other anthropogenic drivers, the impacts may alter species spatio‐temporal distributions and contribute to population declines and local extinctions. To provide timely management and conservation of fishes, it is relevant to identify species that will be most impacted by climate change and those that will be resilient. Species traits are considered a promising source of information on characteristics that influence resilience to various environmental conditions and impacts. To this end, we collated life‐history traits and climatic niches of 443 European freshwater fish species and compared those identified as susceptible to climate change to those that are considered to be resilient. Significant differences were observed between the two groups in their distribution, life history, and climatic niche, with climate‐change‐susceptible species being distributed within the Mediterranean region, and being characterized by greater threat levels, lesser commercial relevance, lower vulnerability to fishing, smaller body and range size, and warmer thermal envelopes. Based on our results, we establish a list of species of highest priority for further research and monitoring regarding climate‐change susceptibility within Europe. The presented approach represents a promising tool to efficiently assess large groups of species regarding their susceptibility to climate change and other threats, and to identify research and management priorities.     

The influence of climate and topography in patterns of territory establishment in a range‐expanding bird

The Dartford Warbler Sylvia undata has recently expanded its range northwards and upwards in the UK, consistent with the hypothesis that this cold‐sensitive species has responded to a warming climate. We interrogated distribution data, collected during four national surveys of this species between 1974 and 2006, to assess whether this large‐scale range expansion has been accompanied by finer‐scale changes in topographic characteristics of breeding locations. Within sites occupied in successive surveys, there was some evidence of limited altitudinal expansion between surveys. Within wider landscapes occupied in successive surveys, the preceding winter climate tended to be harsher at newly colonized sites than at sites that had already been occupied in the previous survey, while territories in newly colonized sites also tended to be on steeper slopes, especially if at higher altitude, and (in 1994 only) to be more south‐facing. Territories in sites that had already been occupied in the previous survey tended to be lower altitude, less steep and more north‐facing than territories in newly colonized landscapes. In 2006 only, the winter climate was significantly milder in newly colonized landscapes than in already occupied sites. The combined effects of a changing climate and topography may have influenced the pattern of in‐filling in the existing range, while colonization of distant areas, especially more latterly, may have been facilitated by a combination of increased dispersal pressure from the existing range and warming of climate which made higher altitude habitat in the new areas more suitable for occupancy. Careful consideration needs to be given to the importance of fine‐scale topographical variation in determining species’ responses to climate change in order to underpin robust adaptation strategies.     

Changes in phenological events in response to a global warming scenario reveal greater adaptability of winter annual compared with summer annual arabidopsis ecotypes

Background and AimsThe impact of global warming on life cycle timing is uncertain. We investigated changes in life cycle timing in a global warming scenario. We compared Arabidopsis thaliana ecotypes adapted to the warm/dry Cape Verdi Islands (Cvi), Macaronesia, and the cool/wet climate of the Burren (Bur), Ireland, Northern Europe. These are obligate winter and summer annuals, respectively.MethodsUsing a global warming scenario predicting a 4 °C temperature rise from 2011 to approx. 2080, we produced F₁ seeds at each end of a thermogradient tunnel. Each F₁ cohort (cool and warm) then produced F₂ seeds at both ends of the thermal gradient in winter and summer annual life cycles. F₂ seeds from the winter life cycle were buried at three positions along the gradient to determine the impact of temperature on seedling emergence in a simulated winter life cycle.Key ResultsIn a winter life cycle, increasing temperatures advanced flowering time by 10.1 d °C^–1 in the winter annual and 4.9 d °C^–1 in the summer annual. Plant size and seed yield responded positively to global warming in both ecotypes. In a winter life cycle, the impact of increasing temperature on seedling emergence timing was positive in the winter annual, but negative in the summer annual. Global warming reduced summer annual plant size and seed yield in a summer life cycle.ConclusionsSeedling emergence timing observed in the north European summer annual ecotype may exacerbate the negative impact of predicted increased spring and summer temperatures on their establishment and reproductive performance. In contrast, seedling establishment of the Macaronesian winter annual may benefit from higher soil temperatures that will delay emergence until autumn, but which also facilitates earlier spring flowering and consequent avoidance of high summer temperatures. Such plasticity gives winter annual arabidopsis ecotypes a distinct advantage over summer annuals in expected global warming scenarios. This highlights the importance of variation in the timing of seedling establishment in understanding plant species responses to anthropogenic climate change.