Distinct responses and range shifts of lizard populations across an elevational gradient under climate change

Ongoing climate change has profoundly affected global biodiversity, but its impacts on populations across elevations remain understudied. Using mechanistic niche models incorporating species traits, we predicted ecophysiological responses (activity times, oxygen consumption and evaporative water loss) for lizard populations at high-elevation (<3600 m asl) and extra-high-elevation (≥3600 m asl) under recent (1970–2000) and future (2081–2100) climates. Compared with their high-elevation counterparts, lizards from extra-high-elevation are predicted to experience a greater increase in activity time and oxygen consumption. By integrating these ecophysiological responses into hybrid species distribution models (HSDMs), we were able to make the following predictions under two warming scenarios (SSP1-2.6, SSP5-8.5). By 2081–2100, we predict that lizards at both high- and extra-high-elevation will shift upslope; lizards at extra-high-elevation will gain more and lose less habitat than will their high-elevation congeners. We therefore advocate the conservation of high-elevation species in the context of climate change, especially for those populations living close to their lower elevational range limits. In addition, by comparing the results from HSDMs and traditional species distribution models, we highlight the importance of considering intraspecific variation and local adaptation in physiological traits along elevational gradients when forecasting species' future distributions under climate change.     

Climate change impacts on endemic,high-elevation lichens in a biodiversity hotspot

Previous studies of the impacts of climate change on lichens and fungi have focused largely on alpine and subalpine habitats, and have not investigated the potential impact on narrowly endemic species. Here, we estimate the impacts of climate change on high-elevation, endemic lichens in the southern Appalachians, a global diversity hotspot for many groups of organisms, including lichens. We conducted extensive field surveys in the high elevations of the region to accurately document the current distributions of eight narrowly endemic lichen species. Species distribution modeling was used to predict how much climatically suitable area will remain within, and north of, the current range of the target species under multiple climate change scenarios at two time points in the future. Our field work showed that target species ranged from extreme rarity to locally abundant. Models predicted over 93 % distributional loss for all species investigated and very little potentially suitable area north of their current distribution in the coming century. Our results indicate that climate change poses a significant threat to high-elevation lichens, and provide a case study in the application of current modeling techniques for rare, montane species.     

Expertly Validated Models and Phylogenetically-Controlled Analysis Suggests Responses to Climate Change Are Related to Species Traits in the Order Lagomorpha

Climate change during the past five decades has impacted significantly on natural ecosystems, and the rate of current climate change is of great concern among conservation biologists. Species Distribution Models (SDMs) have been used widely to project changes in species’ bioclimatic envelopes under future climate scenarios. Here, we aimed to advance this technique by assessing future changes in the bioclimatic envelopes of an entire mammalian order, the Lagomorpha, using a novel framework for model validation based jointly on subjective expert evaluation and objective model evaluation statistics. SDMs were built using climatic, topographical, and habitat variables for all 87 lagomorph species under past and current climate scenarios. Expert evaluation and Kappa values were used to validate past and current models and only those deemed ‘modellable’ within our framework were projected under future climate scenarios (58 species). Phylogenetically-controlled regressions were used to test whether species traits correlated with predicted responses to climate change. Climate change is likely to impact more than two-thirds of lagomorph species, with leporids (rabbits, hares, and jackrabbits) likely to undertake poleward shifts with little overall change in range extent, whilst pikas are likely to show extreme shifts to higher altitudes associated with marked range declines, including the likely extinction of Kozlov’s Pika (Ochotona koslowi). Smaller-bodied species were more likely to exhibit range contractions and elevational increases, but showing little poleward movement, and fecund species were more likely to shift latitudinally and elevationally. Our results suggest that species traits may be important indicators of future climate change and we believe multi-species approaches, as demonstrated here, are likely to lead to more effective mitigation measures and conservation management. We strongly advocate studies minimising data gaps in our knowledge of the Order, specifically collecting more specimens for biodiversity archives and targeting data deficient geographic regions.     

Pleistocene climatic changes drive diversification across a tropical savanna

Spatial responses of species to past climate change depend on both intrinsic traits (climatic niche breadth, dispersal rates) and the scale of climatic fluctuations across the landscape. New capabilities in generating and analysing population genomic data, along with spatial modelling, have unleashed our capacity to infer how past climate changes have shaped populations, and by extension, complex communities. Combining these approaches, we uncover lineage diversity across four codistributed lizards from the Australian Monsoonal Tropics and explore how varying climatic tolerances interact with regional climate history to generate common vs. disparate responses to late Pleistocene change. We find more divergent spatial structuring and temporal demographic responses in the drier Kimberley region compared to the more mesic and consistently suitable Top End. We hypothesize that, in general, the effects of species’ traits on sensitivity to climate fluctuation will be more evident in climatically marginal regions. If true, this points to the need in climatically marginal areas to craft more species‐(or trait)‐specific strategies for persistence under future climate change.     

WHEN COLD IS BETTER: CLIMATE-DRIVEN ELEVATION SHIFTS YIELD COMPLEX PATTERNS OF DIVERSIFICATION AND DEMOGRAPHY IN AN ALPINE SPECIALIST (AMERICAN PIKA, OCHOTONA PRINCEPS)

The genetic consequences of climate-driven range fluctuation during the Pleistocene have been well studied for temperate species, but cold-adapted (e.g., alpine, arctic) species that may have responded uniquely to past climatic events have received less attention. In particular, we have no a priori expectation for long-term evolutionary consequences of elevation shifts into and out of sky islands by species adapted to alpine habitats. Here, we examined the influence of elevation shifts on genetic differentiation and historical demography in an alpine specialist, the American pika ( Ochotona princeps ). Pika populations are divided into five genetic lineages that evolved in association with separate mountain systems, rather than lineages that reflect individual sky islands. This suggests a role for glacial-period elevation shifts in promoting gene flow among high-elevation populations and maintaining regional cohesion of genetic lineages. We detected a signature of recent demographic decline in all lineages, consistent with the expectation that Holocene climate warming has driven range retraction in southern lineages, but unexpected for northern populations that presumably represent postglacial expansion. An ecological niche model of past and future pika distributions highlights the influence of climate on species range and indicates that the distribution of genetic diversity may change dramatically with continued climate warming.     

Identifying potential evolutionary consequences of climate-driven phenological shifts

Climate change is shifting the phenology of many species throughout the world. While the interspecific consequences of these phenological shifts have been well documented, the intraspecific shifts and their resultant evolutionary consequences remain relatively unexplored. Here, we present a conceptual framework and overview of how phenological shifts within species can drive evolutionary change. We suggest that because the impacts of climate change are likely to vary across the range of a species and differentially impact individuals, phenological shifts may often be highly variable both within and among populations. Together these changes have the potential to alter existing patterns of gene flow and influence evolutionary trajectories by increasing phenological isolation and connectivity. Recent research examining the response of species to contemporary climate change suggests that both phenological isolation and connectivity may be likely responses to future climate change. However, recent studies also show mixed results on whether adaptive responses to climate change are likely to occur, as some populations have already shown adaptive responses to changing climate, while others have not despite fitness costs. While predicting the exact consequences of intraspecific phenological shifts may be difficult, identifying the evolutionary implications of these shifts will allow a better understanding of the effects of future climate change on species persistence and adaptation.     

Running to stand still: adaptation and the response of plants to rapid climate change

Climate is a potent selective force in natural populations, yet the importance of adaptation in the response of plant species to past climate change has been questioned. As many species are unlikely to migrate fast enough to track the rapidly changing climate of the future, adaptation must play an increasingly important role in their response. In this paper we review recent work that has documented climate‐related genetic diversity within populations or on the microgeographical scale. We then describe studies that have looked at the potential evolutionary responses of plant populations to future climate change. We argue that in fragmented landscapes, rapid climate change has the potential to overwhelm the capacity for adaptation in many plant populations and dramatically alter their genetic composition. The consequences are likely to include unpredictable changes in the presence and abundance of species within communities and a reduction in their ability to resist and recover from further environmental perturbations, such as pest and disease outbreaks and extreme climatic events. Overall, a range‐wide increase in extinction risk is likely to result. We call for further research into understanding the causes and consequences of the maintenance and loss of climate‐related genetic diversity within populations.     

Cross-continent comparisons reveal differing environmental drivers of growth of the coral reef fish, <Emphasis Type="Italic">Lutjanus bohar</Emphasis>

Biochronologies provide important insights into the growth responses of fishes to past variability in physical and biological environments and, in so doing, allow modelling of likely responses to climate change in the future. We examined spatial variability in the key drivers of inter-annual growth patterns of a widespread, tropical snapper, Lutjanus bohar, at similar tropical latitudes on the north-western and north-eastern coasts of the continent of Australia. For this study, we developed biochronologies from otoliths that provided proxies of somatic growth and these were analysed using mixed-effects models to examine the historical drivers of growth. Our analyses demonstrated that growth patterns of fish were driven by different climatic and biological factors in each region, including Pacific Ocean climate indices, regional sea level and the size structure of the fish community. Our results showed that the local oceanographic and biological context of reef systems strongly influenced the growth of L. bohar and that a single age-related growth trend cannot be assumed for separate populations of this species that are likely to experience different environmental conditions. Generalised predictions about the growth response of fishes to climate change will thus require adequate characterisation of the spatial variability in growth determinants likely to be found throughout the range of species that have cosmopolitan distributions.     

The shaping of genetic variation in edge‐of‐range populations under past and future climate change

With rates of climate change exceeding the rate at which many species are able to shift their range or adapt, it is important to understand how future changes are likely to affect biodiversity at all levels of organisation. Understanding past responses and extent of niche conservatism in climatic tolerance can help predict future consequences. We use an integrated approach to determine the genetic consequences of past and future climate changes on a bat species, Plecotus austriacus. Glacial refugia predicted by palaeo‐modelling match those identified from analyses of extant genetic diversity and model‐based inference of demographic history. Former refugial populations currently contain disproportionately high genetic diversity, but niche conservatism, shifts in suitable areas and barriers to migration mean that these hotspots of genetic diversity are under threat from future climate change. Evidence of population decline despite recent northward migration highlights the need to conserve leading‐edge populations for spearheading future range shifts.     

High-elevation plants have reduced plasticity in flowering time in response to warming compared to low-elevation congeners

Global warming has caused shifts in the flowering time of many plant species. In alpine regions the temperature rise has been especially pronounced and together with decreasing winter precipitation has led to earlier snowmelt. The close association between time of snowmelt and plant growth at high elevations makes climate change for alpine plants particularly threatening. Here we transplanted eleven congeneric pairs of high- and low-elevation herbaceous species to common gardens differing c. 800 m in elevation, and c. 4 °C in mean growing season temperature to test whether reproductive phenologies of high- and low-elevation plants differ in their respective responses to temperature. Results indicate that high-elevation plants were less plastic in response to transplantation than their low-elevation congeners as the onsets of phenophases on average shifted 7 days less than in low-elevation plants. Plasticity of phenophase durations was overall weaker than that of phenophase onsets, and slightly stronger in high-elevation species compared to low-elevation congeners. We suggest that weaker plasticity in the onsets of early stages of reproductive phenology of high-elevation plants is related to spring frost, which constitutes a strong selective agent against early loss of winter hardiness. Some of the plastic responses of both low- and high-elevation species might potentially be adaptive under predicted climate change. However, the observed plasticity can be largely explained as a passive response to temperature and not as the result of natural selection in heterogeneous environments. The strong temperature-sensitivity of low-elevation species might promote their upward range expansion, but only to a certain threshold after which it becomes limited by the short growing season.     

Adaptive thermoregulation in endotherms may alter responses to climate change

Climate change is one of the major issues facing natural populations and thus a focus of recent research has been to predict the responses of organisms to these changes. Models are becoming more complex and now commonly include physiological traits of the organisms of interest. However, endothermic species have received less attention than have ectotherms in these mechanistic models. Further, it is not clear whether responses of endotherms to climate change are modified by variation in thermoregulatory characteristics associated with phenotypic plasticity and/or adaptation to past selective pressures. Here, we review the empirical data on thermal adaptation and acclimatization in endotherms and discuss how those factors may be important in models of responses to climate change. We begin with a discussion of why thermoregulation and thermal sensitivity at high body temperatures should be co-adapted. Importantly, we show that there is, in fact, considerable variation in the ability of endotherms to tolerate high body temperatures and/or high environmental temperatures, but a better understanding of this variation will likely be critical for predicting responses to future climatic scenarios. Next, we discuss why variation in thermoregulatory characteristics should be considered when modeling the effects of climate change on heterothermic endotherms. Finally, we review some biophysical and biochemical factors that will limit adaptation and acclimation in endotherms. We consider both long-term, directional climate change and short-term (but increasingly common) anomalies in climate such as extreme heat waves and we suggest areas of important future research relating to both our basic understanding of endothermic thermoregulation and the responses of endotherms to climate change.     

Spatial and temporal heterogeneity in climate change limits species' dispersal capabilities and adaptive potential

Global climate change has already caused local declines and extinctions. These losses are generally thought to occur because climate change is progressing too rapidly for populations to keep pace. Based on this hypothesis, numerous predictive frameworks have been developed to project future range shifts and changes in population dynamics resulting from global climate change. However, recent empirical work has demonstrated that seasonally asynchronous climate change regimes – when a region is warming during some parts of the year, but cooling in others – are constraining species' responses to climate change more strongly than rapid warming, leading to intra‐specific variation in responses to climate change and local population declines. Here, we couple a review of the literature related to asynchronous climate change regimes with meta‐population simulations and an analysis of long‐term North American climate trends to show that seasonally asynchronous regimes are occurring throughout most of North America and that their current spatial distribution may be a strong barrier to dispersal and gene flow across many species' ranges. Thus, even though adaptation to climate change may potentially be more common and rapid than previously thought, species whose ranges overlap with asynchronous regimes will likely succumb to local declines that may be difficult to mitigate via dispersal. Future climate‐related predictive frameworks should therefore incorporate asynchronous regimes as well as more traditional measures of climate velocity in order to fully capture the array of potential future climate change scenarios.     

Losing ground: past history and future fate of Arctic small mammals in a changing climate

According to the IPCC, the global average temperature is likely to increase by 1.4–5.8 °C over the period from 1990 to 2100. In Polar regions, the magnitude of such climatic changes is even larger than in temperate and tropical biomes. This amplified response is particularly worrisome given that the so‐far moderate warming is already impacting Arctic ecosystems. Predicting species responses to rapid warming in the near future can be informed by investigating past responses, as, like the rest of the planet, the Arctic experienced recurrent cycles of temperature increase and decrease (glacial–interglacial changes) in the past. In this study, we compare the response of two important prey species of the Arctic ecosystem, the collared lemming and the narrow‐skulled vole, to Late Quaternary climate change. Using ancient DNA and Ecological Niche Modeling (ENM), we show that the two species, which occupy similar, but not identical ecological niches, show markedly different responses to climatic and environmental changes within broadly similar habitats. We empirically demonstrate, utilizing coalescent model‐testing approaches, that collared lemming populations decreased substantially after the Last Glacial Maximum; a result consistent with distributional loss over the same period based on ENM results. Given this strong association, we projected the current niche onto future climate conditions based on IPCC 4.0 scenarios, and forecast accelerating loss of habitat along southern range boundaries with likely associated demographic consequences. Narrow‐skulled vole distribution and demography, by contrast, was only moderately impacted by past climatic changes, but predicted future changes may begin to affect their current western range boundaries. Our work, founded on multiple lines of evidence suggests a future of rapidly geographically shifting Arctic small mammal prey communities, some of whom are on the edge of existence, and whose fate may have ramifications for the whole Arctic food web and ecosystem.     

Lower plasticity exhibited by high- versus mid-elevation species in their phenological responses to manipulated temperature and drought

Background and Aims Recent global changes, particularly warming and drought, have had worldwide repercussions on the timing of flowering events for many plant species. Phenological shifts have also been reported in alpine environments, where short growing seasons and low temperatures make reproduction particularly challenging, requiring fine-tuning to environmental cues. However, it remains unclear if species from such habitats, with their specific adaptations, harbour the same potential for phenological plasticity as species from less demanding habitats.Methods Fourteen congeneric species pairs originating from mid and high elevation were reciprocally transplanted to common gardens at 1050 and 2000 m a.s.l. that mimic prospective climates and natural field conditions. A drought treatment was implemented to assess the combined effects of temperature and precipitation changes on the onset and duration of reproductive phenophases. A phenotypic plasticity index was calculated to evaluate if mid- and high-elevation species harbour the same potential for plasticity in reproductive phenology.Key Results Transplantations resulted in considerable shifts in reproductive phenology, with highly advanced initiation and shortened phenophases at the lower (and warmer) site for both mid- and high-elevation species. Drought stress amplified these responses and induced even further advances and shortening of phenophases, a response consistent with an ‘escape strategy’. The observed phenological shifts were generally smaller in number of days for high-elevation species and resulted in a smaller phenotypic plasticity index, relative to their mid-elevation congeners.Conclusions While mid- and high-elevation species seem to adequately shift their reproductive phenology to track ongoing climate changes, high-elevation species were less capable of doing so and appeared more genetically constrained to their specific adaptations to an extreme environment (i.e. a short, cold growing season).     

Upward elevation and northwest range shifts for alpine Meconopsis species in the Himalaya–Hengduan Mountains region

Climate change may impact the distribution of species by shifting their ranges to higher elevations or higher latitudes. The impacts on alpine plant species may be particularly profound due to a potential lack of availability of future suitable habitat. To identify how alpine species have responded to climate change during the past century as well as to predict how they may react to possible global climate change scenarios in the future, we investigate the climatic responses of seven species of Meconopsis, a representative genus endemic in the alpine meadow and subnival region of the Himalaya–Hengduan Mountains. We analyzed past elevational shifts, as well as projected shifts in longitude, latitude, elevation, and range size using historical specimen records and species distribution modeling under optimistic (RCP 4.5) and pessimistic (RCP 8.5) scenarios across three general circulation models for 2070. Our results indicate that across all seven species, there has been an upward shift in mean elevation of 302.3 m between the pre‐1970s (1922–1969) and the post‐1970s (1970–2016). The model predictions suggest that the future suitable climate space will continue to shift upwards in elevation (as well as northwards and westwards) by 2070. While for most of the analyzed species, the area of suitable climate space is predicted to expand under the optimistic emission scenario, the area contracts, or, at best, shows little change under the pessimistic scenario. Species such as M. punicea, which already occupy high latitudes, are consistently predicted to experience a contraction of suitable climate space across all the models by 2070 and may consequently deserve particular attention by conservation strategies. Collectively, our results suggest that the alpine high‐latitude species analyzed here have already been significantly impacted by climate change and that these trends may continue over the coming decades.     

Climate and habitat availability determine 20th century changes in a butterfly's range margin

Evidence of anthropogenic global climate change is accumulating, but its potential consequences for insect distributions have received little attention. We use a ''climate response surface'' model to investigate distribution changes at the northern margin of the speckled wood butterfly, Pararge aegeria. We relate its current European distribution to a combination of three bioclimatic variables. We document that P. aegeria has expanded its northern margin substantially since 1940, that changes in this species'' distribution over the past 100 years are likely to have been due to climate change, and that P. aegeria will have the potential to shift its range margin substantially northwards under predicted future climate change. At current rates of expansion, this species could potentially colonize all newly available climatically suitable habitat in the UK over the next 50 years or more. However, fragmentation of habitats can affect colonization, and we show that availability of habitat may be constraining range expansion of this species at its northern margin in the UK. These lag effects may be even more pronounced in less-mobile species inhabiting more fragmented landscapes, and highlight how habitat distribution will be crucial in predicting species'' responses to future climate change.     

Elevational differences in developmental plasticity determine phenological responses of grasshoppers to recent climate warming

Annual species may increase reproduction by increasing adult body size through extended development, but risk being unable to complete development in seasonally limited environments. Synthetic reviews indicate that most, but not all, species have responded to recent climate warming by advancing the seasonal timing of adult emergence or reproduction. Here, we show that 50 years of climate change have delayed development in high-elevation, season-limited grasshopper populations, but advanced development in populations at lower elevations. Developmental delays are most pronounced for early-season species, which might benefit most from delaying development when released from seasonal time constraints. Rearing experiments confirm that population, elevation and temperature interact to determine development time. Population differences in developmental plasticity may account for variability in phenological shifts among adults. An integrated consideration of the full life cycle that considers local adaptation and plasticity may be essential for understanding and predicting responses to climate change.     

Unusual suspects in the usual places: a phylo-climatic framework to identify potential future invasive species

A framework for identifying species that may become invasive under future climate conditions is presented, based on invader attributes and biogeography in combination with projections of future climate. We illustrate the framework using the CLIMEX niche model to identify future climate suitability for three species of Hawkweed that are currently present in the Australian Alps region and related species that are present in the neighbouring region. Potential source regions under future climate conditions are identified, and species from those emerging risk areas are identified. We use dynamically downscaled climate projections to complement global analyses and provide fine-scale projections of suitable climate for current and future (2070–2099) conditions at the regional scale. Changing climatic conditions may reduce the suitability for some invasive species and improve it for others. Invasive species with distributions strongly determined by climate, where the projected future climate is highly suitable, are those with the greatest potential to be future invasive species in the region. As the Alps region becomes warmer and drier, many more regions of the world become potential sources of invasive species, although only one additional species of Hawkweed is identified as an emerging risk. However, in the longer term, as the species in these areas respond to global climate change, the potential source areas contract again to match higher altitude regions. Knowledge of future climate suitability, based on species-specific climatic tolerances, is a useful step towards prioritising management responses such as targeted eradication and early intervention to prevent the spread of future invasive species.     

气候变暖对陆地植被-土壤生态系统的影响研究

由于自然因素及人类活动的长期影响,全球气候变化已经成为不容置疑的事实,并对陆地生态系统的植被及土壤产生了深远影响。陆地植被一土壤生态系统在全球气候变化中的反应与适应等过程已成为众多科学家所关注的问题。为更好地了解陆地植被一土壤生态系统对全球气候变化的响应机制,综述了气候变暖对植物的物候与生长、光合特征、生物量生产与分配,以及土壤呼吸等方面的影响,并对分析得到的结论进行了总结。分析指出,随着全球气候变暖,植物个体和群落特征以及土壤特性都会发生相应改变,高海拔地区的植被高度有增加趋势,而低海拔地区的植被可能出现矮化。然而,在以下方面还存有不确定性：（1）气候变暖导致的植被特征变化是否会减弱全球气候变化;（2）在较长时间尺度上气候变暖如何影响植物的物候和生长,特别是植物的体型;（3）高寒生态系统冬季土壤呼吸对气候变暖如何响应。