Species Range Changes Research Articles

Expanding the boundaries in the face of global warming: A lesson from genetic and ecological niche studies of Centaurium erythraea in Europe

Climate change affects plant species, especially those with restricted ecology and distribution. Centaurium erythraea is a flowering plant species in the Gentianaceae family, native to Europe, with its centre of diversity in the Mediterranean and western Asia. Of the 11 infraspecific taxa distinct from C. erythraea, only two are common in Europe: C. erythraea subsp. erythraea (widespread nominal subspecies) and C. erythraea subsp. majus (mainly distributed in the western Mediterranean region). Freshly collected samples of 36 plants from 11 localities across Lower Silesia (Central Europe) were utilised for taxonomic and genetic analysis. The barcode sequences of chloroplast DNA region matK were used for molecular analysis. Data deposited in GenBank was also used. Five haplotypes were identified among the analysed specimens. Species Distribution Modelling (SDM) techniques were applied to predict the current and future (short- and long-term projections) potential distribution of C. erythraea subsp. majus and to identify the most influential climatic factors. Despite the typical Mediterranean distribution, the presence of C. erythraea subsp. majus outside its natural range in SW Poland has been confirmed by morphological and genetic studies. The mean monthly precipitation of the wettest quarter and the mean daily temperatures of the warmest quarter were identified as the key climatic factors. Short-term scenarios suggest that C. erythraea subsp. majus will maintain most of its current suitable habitats and potentially expand into the lowlands of Central Europe. However, long-term projections indicate a potential reduction in its currently suitable areas, especially in the southern parts of its range, with a possible expansion into north-western Europe. The results of these studies provide clear evidence of the impact of ongoing climate change on species range changes. These findings suggest that climate change may create new opportunities for Mediterranean species to spread to new regions, using C. erythraea subsp. majus as an example.

Climate change in open environments: Revisiting the current distribution to understand and safeguard the future of psammophilous squamates of the Diagonal of Open Formations of South America

To identify regions that contribute to the persistence of biodiversity, we (1) predict the potential distribution of the psammophilous squamate species endemic of the Diagonal of Open Formations (DOF) in the current climate, (2) identify survey priority areas, (3) estimate the impacts of climate change in two future CO2 emission scenarios, and (4) discuss strategies to safeguard these target species. We created an occurrence database and used environmental variables for the current and future periods to run the potential distribution models. We obtained models with high performance for all species and scenarios. Our study indicates potential occurrence areas for the psammophilous squamates of the DOF that still need to be sampled and are a survey priority for future inventories. In all future projections, climate change is predicted to shift the suitability and promote species range change, modifying the richness patterns for the psammophilous squamate reptiles of DOF. Finally, we demonstrate that future climatic conditions may decrease the effectiveness of current areas in protecting the diversity of these reptiles. Our results highlight the vulnerability of psammophilous squamates from South American Dry Diagonal to climate change and provide crucial information of the need of dynamic public policies for conservation of these species.

Contrasting range changes of terrestrial orchids under future climate change in China

Climate change has impacted the distribution and abundance of numerous plant and animal species during the last century. Orchidaceae is one of the largest yet most threatened families of flowering plants. However, how the geographical distribution of orchids will respond to climate change is largely unknown. Habenaria and Calanthe are among the largest terrestrial orchid genera in China and around the world. In this paper, we modeled the potential distribution of eight Habenaria species and ten Calanthe species in China under the near-current period (1970–2000) and the future period (2081–2100) to test the following two hypotheses: 1) narrow-ranged species are more vulnerable to climate change than wide-ranged species; 2) niche overlap between species is positively correlated with their phylogenetic relatedness. Our results showed that most Habenaria species will expand their ranges, although the climatic space at the southern edge will be lost for most Habenaria species. In contrast, most Calanthe species will shrink their ranges dramatically. Contrasting range changes between Habenaria and Calanthe species may be explained by their differences in climate-adaptive traits such as underground storage organs and evergreen/deciduous habits. Habenaria species are predicted to generally shift northwards and to higher elevations in the future, while Calanthe species are predicted to shift westwards and to higher elevations. The mean niche overlap among Calanthe species was higher than that of Habenaria species. No significant relationship between niche overlap and phylogenetic distance was detected for both Habenaria and Calanthe species. Species range changes in the future was also not correlated with their near current range sizes for both Habenaria and Calanthe. The results of this study suggest that the current conservation status of both Habenaria and Calanthe species should be adjusted. Our study highlights the importance of considering climate-adaptive traits in understanding the responses of orchid taxa to future climate change.

Leveraging a century of fisheries surveys to prioritize conservation efforts for species in Great Plains streams of Oklahoma (USA)

Abstract Although non‐game fishes typically dominate lists of threatened and imperilled species, funding mechanisms for non‐game species are usually less robust than those for game species. This imbalance emphasizes the need for methodologies to identify imperilled species effectively and ensure efficient allocation of limited conservation resources. A database comprising >3,900 fisheries surveys conducted between 1905 and 2020 in Great Plains streams of Oklahoma (USA) was used to develop methodology for identifying species in need of conservation by assessing differences in species occurrences and trends in species ranges through time. Changes in occurrence for 92 species at both river catchment and ecoregion scales were assessed. Generalized linear models indicated significant differences between historical and contemporary fish communities at both scales. Univariate testing showed 84 instances of species occurrences changing in at least one catchment. Declines in occurrence were observed for eight species currently listed as species of greatest conservation need in Oklahoma and were used to identify five candidate species for listing. Family‐level trends in species occurrences suggested declines of native true minnow species and increases in generalist sunfishes and catfishes through time. Trends in detections within each hydrologic unit code sampled were used as a proxy for tracking changes in species range within each catchment. Various species were used as case studies to highlight this method. The results demonstrate how managers can apply an empirical methodology that extracts information from long‐term datasets to optimize conservation efforts for stream fishes and associated taxa.

Impacts of climate change on the distribution of riverine endemic fish species in Iran, a biodiversity hotspot region

Abstract Iran is one of the world's fish biodiversity hotspots. Most riverine fish species in this country are currently under threat by human activities. In addition to those threats, climate change is expected to alter rainfall and temperature regimes, imposing further limitations, particularly to endemic fishes. Therefore, understanding how these species respond to climate change is an important issue in the conservation of Iranian freshwater biodiversity. This study aimed to predict the potential distribution of 16 endemic fish species under two climate change scenarios (i.e., RCP 4.5 and RCP 8.5) in river habitats of Iran in the 2050s and the 2080s. The analysis is conducted using the MaxEnt model. Seven environmental variables were used for modelling: maximum width, elevation, river slope, the basins occupied by the target species, average annual precipitation, annual mean temperature, and the temperature difference between the coldest and hottest months of the year . The validation of the model for each species showed that AUC (area under the ROC curve) scores range from 0.87 to 0.99. Under optimistic (RCP 4.5) and pessimistic (RCP 8.5) scenarios in the 2050s and the 2080s, species will face four different outcomes to their habitat range: reduction (three species), expansion (five species), reduction and expansion (seven species) and no change (one species). It is concluded that most species that are unique in their geographical area will face serious challenges from climate change. Delineating species range changes under climate change scenarios can help prioritise conservation measures for these valuable species. Considering our results, the translocation of species to new locations also should be investigated.

Effects of climate change and anthropogenic activity on ranges of vertebrate species endemic to the Qinghai-Tibet Plateau over 40years.

Over the past 40years, the climate has been changing and human disturbance has increased in the vast Qinghai-Tibet Plateau (QTP). These 2 factors are expected to affect the distribution of a large number of endemic vertebrate species. However, quantitative relationships between range shifts and climate change and human disturbance of these species in the QTP have rarely been evaluated. We used occurrence records of 19 terrestrial vertebrate species (birds, mammals, amphibians, and reptiles) occurring in the QTP from 1980 to 2020 to quantify the effects of climate change and anthropogenic impacts on the distribution of these 4 taxonomic groups and estimated species range changes in each species. The trend in distribution changes differed among the taxonomic groups, although, generally, ranges shifted to central QTP. Climate change contributed more to range variation than human disturbance (the sum of the 4 climatic variables contributed more than the sum of the 4 human disturbance variables for all 4 taxonomic groups). Suitable geographic range increased for most mammals, amphibians, and reptiles (+27.6%, +18.4%, and +27.8% on average, respectively), whereas for birds range decreased on average by 0.9%. Quantitative evidence for climate change and human disturbance associations with range changes for endemic vertebrate species in the QTP can provide useful insights into biodiversity conservation under changing environments.

Mammals of Hazeldell Nature Preserve, Pulaski County, Kentucky: A Rare Highland Rim Ecosystem

Hazeldell Nature Preserve is a rare ecosystem on the Highland Rim of south-central Kentucky. It is the only state-protected site of its kind. This preserve is comprised of two distinct plant communities, including wet flatwoods and wet meadow. Despite its uniqueness, no ecological studies have been conducted on mammals in the past. Currently, two separate studies are underway on mammals. Here we present the results from the first of these that used camera traps set in the wet flatwoods community from 1 February to 28 March 2020. A total of 34,071 photos were taken with 553 having images of 12 species of mammals. The four most photographed species were eastern gray squirrel, Virginia opossum, white-footed deermouse, and white-tailed deer. These four species appeared in 91% of photos. The remaining 49 photos were of eight species including: eastern cottontail, coyote, bobcat, northern raccoon, striped skunk, southern flying squirrel, common gray fox, and eastern fox squirrel. Woodchuck and eastern chipmunk were not photographed during the study, yet each have ranges that include the preserve. These burrowers may avoid the preserve because of the secondary water table and saturated soil that occur during extended periods. The results of this study serve as baseline data for comparison to future camera trapping. Continued photo documentation will be used to identify changes in the mammal species composition of the preserve caused by species range changes in response to various factors, including habitat fragmentation and climate change.

Warmer Ambient Temperatures Depress Detoxification and Food Intake by Marsupial Folivores

Ambient temperature is an underappreciated determinant of foraging behaviour in wild endotherms, and the requirement to thermoregulate likely influences food intake through multiple interacting mechanisms. We investigated relationships between ambient temperature and hepatic detoxification capacity in two herbivorous marsupials, the common ringtail possum (Pseudocheirus peregrinus) and common brushtail possum (Trichosurus vulpecula) that regularly feed on diets rich in plant toxins. As an indicator of hepatic detoxification capacity, we determined the functional clearance rate of an anaesthetic agent, Alfaxalone, after possums were acclimated to 10°C [below the thermoneutral zone (TNZ)], 18°C [approximately lower critical temperature (LCT)], and 26°C [approximately upper critical temperature (UCT)] for either 7 days or less than 24 h. We then measured intake of foods with high or low plant secondary metabolite (PSM) concentrations under the same temperature regimes. After 7 days of acclimation, we found a positive correlation between the functional clearance rate of Alfaxalone and ambient temperature, and a negative relationship between ambient temperature and intake of foods with high or low PSM concentrations for both species. The effect of ambient temperature on intake of diets rich in PSMs was absent or reduced when possums were kept at temperatures for less than 24 h. Our results underscore the effects of ambient temperature in hepatic metabolism particularly with respect intake of diets containing PSMs. Given that the planet is warming, it is vital that effects of ambient temperature on metabolism, nutrition and foraging by mammalian herbivores is taken into account to predict range changes of species and their impact on ecosystems.

High Phenotypic Plasticity, but Low Signals of Local Adaptation to Climate in a Large-Scale Transplant Experiment of Picea abies (L.) Karst. in Europe

The most common tool to predict future changes in species range are species distribution models. These models do, however, often underestimate potential future habitat, as they do not account for phenotypic plasticity and local adaptation, although being the most important processes in the response of tree populations to rapid climate change. Here, we quantify the difference in the predictions of future range for Norway spruce, by (i) deriving a classic, occurrence-based species distribution model (OccurrenceSDM), and (ii) analysing the variation in juvenile tree height and translating this to species occurrence (TraitSDM). Making use of 32 site locations of the most comprehensive European trial series that includes 1,100 provenances of Norway spruce originating from its natural and further beyond from its largely extended, artificial distribution, we fit a universal response function to quantify growth as a function of site and provenance climate. Both the OccurrenceSDM and TraitSDM show a substantial retreat towards the northern latitudes and higher elevations (−55 and −43%, respectively, by the 2080s). However, thanks to the species’ particularly high phenotypic plasticity in juvenile height growth, the decline is delayed. The TraitSDM identifies increasing summer heat paired with decreasing water availability as the main climatic variable that restricts growth, while a prolonged frost-free period enables a longer period of active growth and therefore increasing growth potential within the restricted, remaining area. Clear signals of local adaptation to climatic clines spanning the entire range are barely detectable, as they are disguised by a latitudinal cline. This cline strongly reflects population differentiation for the Baltic domain, but fails to capture the high phenotypic variation associated to the geographic heterogeneity in the Central European mountain ranges paired with the species history of postglacial migration. Still the model is used to provide recommendations of optimal provenance choice for future climate conditions. In essence, assisted migration may not decrease the predicted range decline of Norway spruce, but may help to capitalize on potential opportunities for increased growth associated with warmer climates.

Here be dragons: important spatial uncertainty driven by climate data in forecasted distribution of an endangered insular reptile

AbstractThe effect of future climate change is poorly studied in the tropics, especially in mountainous areas, yet species living in these environments are predicted to be strongly affected. Newly available high‐resolution environmental data and statistical methods enable the development of forecasting models, but the uncertainty related to climate models can be strong, which can lead to ineffective conservation actions. Predictive studies aimed at providing conservation guidelines often account for a range of future climate predictions (climate scenarios and global circulation models). However, very few studies consider potential differences related to the source of climate data and/or do not account for spatial information (overlap) in uncertainty assessments. We modelled the environmental suitability for Phelsuma borbonica, an endangered reptile native to Reunion Island. Using two metrics of species range change (difference in overall suitability and spatial overlap), we quantified the uncertainty related to the modelling technique (n = 10), sample bias correction, climate change scenario, global circulation models (GCM) and data source (CHELSA vs. Worldclim). Uncertainty was mainly driven by GCMs when considering overall suitability, while for spatial overlap, the uncertainty related to data source became more important than that of GCMs. The uncertainty driven by sample bias correction and variable selection was much higher when assessed based on the spatial overlap. The modelling technique was a strong driver of uncertainty in both cases. We provide a consensus ensemble prediction map of the environmental suitability of P. borbonica to identify the areas predicted to be the most suitable in the future with the highest certainty. Predictive studies aimed at identifying priority areas for conservation in the face of climate change need to account for a wide panel of modelling techniques, GCMs and data sources. We recommend the use of multiple approaches, including spatial overlap when assessing uncertainty in species distribution models.

Empowering her guardians to nurture our Ocean\u2019s future

Coastal Indigenous and Traditional communities are starting to see changes to their lives from climate change, whether this is from species range changes or displacement from land changes. For many of these communities, the ability to adequately adapt to these changes is limited by the governance structures they are required to live within, which differ from their customary practices and culture. In November 2019, a group of Indigenous and Traditional Peoples, attended the Future Seas 2030 workshop and discussed the consequences of climate change, the biggest barriers for their communities, and barriers for using traditional knowledge in order to contribute towards a more sustainable future that in the end will benefit all of earth’s people. The aim of this workshop was to highlight and give a voice to the various backgrounds and real-life situations impacting on some of the world’s Indigenous and Traditional communities whose connection with the oceans and coasts have been disrupted. This paper presents these issues of oppression, colonisation, language and agency, making it difficult for these groups to contribute to the current management of oceans and coasts, and asks scientists and practitioners in this space to be allies and enable the needed shift to earth’s guardians taking a leading role in nurturing her for our future.

Recent changes of entomofaunal diversity in meadow-steppe habitats of northwest Podillia (on example of Lepidoptera)

Based on the results of perennial investigations and reference data analysis, an estimation of entomofaunal diversity changes is carried out for meadow-steppe habitats of NW Podillia (Lviv Oblast, Ukraine) on the example of one of the best-known taxonomical groups (Lepidoptera). An approbation of formerly elaborated methods for the monitoring of key invertebrate groups diversity, which indicate ecosystem conditions, was worked out. Complex eco-geographical analysis of species composition as well as retrospective evaluation of several species range changes shows the progressive decline in diversity at the expense of the most unique grassland and forest-steppe faunal elements. The general factors that threaten entomofaunal diversity of meadow-steppe habitats are spatial structure changes because of artificial or spontaneous afforestation, decrease and fragmentation of its area because of economic activities and the impact of climate changes.

Anthropogenic climate change impacts on copepod trait biogeography.

Copepods are among the most abundant marine metazoans and form a key link between marine primary producers, higher trophic levels, and carbon sequestration pathways. Climate change is projected to change surface ocean temperature by up to 4°C in the North Atlantic with many associated changes including slowing of the overturning circulation, areas of regional freshening, and increased salinity and reductions in nutrients available in the euphotic zone over the next century. These changes will lead to a restructuring of phytoplankton and zooplankton communities with cascading effects throughout the food web. Here we employ observations of copepods, projected changes in ocean climate, and species distribution models to show how climate change may affect the distribution of copepod species in the North Atlantic. On average species move northeast at a rate of 14.1kmdecade-1 . Species turnover in copepod communities will range from 5% to 75% with the highest turnover rates concentrated in regions of pronounced temperature increase and decrease. The changes in species range vary according to copepod traits with the largest effects found to occur in the cooling, freshening area in the subpolar North Atlantic south of Greenland and in an area of significant warming along the Scotian shelf. Large diapausing copepods (>2.5mm) which are higher in lipids and a crucial food source for whales, may have an advantage in the cooling waters due to their life-history strategy that facilitates their survival in the arctic environment. Carnivorous copepods show a basin wide increase in species richness and show significant habitat area increases when their distribution moves poleward while herbivores see significant habitat area losses. The trait-specific effects highlight the complex consequences of climate change for the marine food web.

Influence of climate-induced biogeographic range shifts on mudflat ecological functioning in the subtropics

A growing volume of evidence shows that the broad-scale biogeographic redistribution of species is occurring in response to increasing global temperatures. The present study documents poleward movements of up to eight species of nominally ‘tropical’ macroinvertebrates (molluscs, polychaetes, crustaceans and foraminifera) from intertidal mudflats on the south east coast of Australia. The speed of movement was comparable with that for Australian marine fauna generally, but was particularly fast for worms and molluscs (~70–300 km decade−1) and may be facilitated by the southward flowing East Australia Current. Further, two temperate taxa appear to have extended their ranges northwards. Changes in species biogeographic ranges raises questions surrounding the response of ecological processes within the altered and novel species combinations, including processes that underpin valuable ecosystem services. Using biological traits analysis to investigate how the observed species range changes might have impacted mudflat ecosystem functioning, and to predict the possible impacts of further poleward movements of tropical taxa. Our models suggest the changes to date, and those likely to occur in the near future, are within the envelope whereby ecological functioning is maintained by functional compensation and redundancy within the mudflat assemblage. However, in the most extreme scenario the replacement of temperate by tropical taxa resulted in major changes in ecological functioning with potential impacts on nutrient cycling and C-cycling, undermining the potential of these mudflats to continue to deliver critical ecosystem services. The widespread nature of biogeographic range shifts and the value of coastal systems should add further weight to calls for global action to mitigate global temperature change.

Accelerated increase in plant species richness on mountain summits is linked to warming.

Globally accelerating trends in societal development and human environmental impacts since the mid-twentieth century 1-7 are known as the Great Acceleration and have been discussed as a key indicator of the onset of the Anthropoceneepoch 6 . While reports on ecological responses (for example, changes in species range or local extinctions) to the Great Acceleration are multiplying 8, 9 , it is unknown whether such biotic responses are undergoing a similar acceleration over time. This knowledge gap stems from the limited availability of time series data on biodiversity changes across large temporal and geographical extents. Here we use a dataset of repeated plant surveys from 302 mountain summits across Europe, spanning 145 years of observation, to assess the temporal trajectory of mountain biodiversity changes as a globally coherent imprint of the Anthropocene. We find a continent-wide acceleration in the rate of increase in plant species richness, with five times as much species enrichment between 2007 and 2016 as fifty years ago, between 1957 and 1966. This acceleration is strikingly synchronized with accelerated global warming and is not linked to alternative global change drivers. The accelerating increases in species richness on mountain summits across this broad spatial extent demonstrate that acceleration in climate-induced biotic change is occurring even in remote places on Earth, with potentially far-ranging consequences not only for biodiversity, but also for ecosystem functioning and services.

Moving beyond presence and absence when examining changes in species distributions.

Species distributions are often simplified to binary representations of the ranges where they are present and absent. It is then common to look for changes in these ranges as indicators of the effects of climate change, the expansion or control of invasive species or the impact of human land-use changes. We argue that there are inherent problems with this approach, and more emphasis should be placed on species relative abundance rather than just presence. The sampling effort required to be confident of absence is often impractical to achieve, and estimates of species range changes based on survey data are therefore inherently sensitive to sampling intensity. Species niches estimated using presence-absence or presence-only models are broader than those for abundance and may exaggerate the viability of small marginal sink populations. We demonstrate that it is possible to transform models of predicted probability of presence to expected abundance if the sampling intensity is known. Using case studies of Antarctic mosses and temperate rain forest trees, we demonstrate additional insights into biotic change that can be gained using this method. While species becoming locally extinct or colonising new areas are extreme and obviously important impacts of global environmental change, changes in abundance could still signal important changes in biological systems and be an early warning indicator of larger future changes.

Did British breeding birds move north in the late 20th century?

Contemporary climate change is the biggest experiment ever conducted by humans on a planetary scale, and its impact on the redistribution of life is potentially huge (e.g., Barnosky et al. Nature 471:51–57, 2011, Pereira et al. Science 330:1496–1501, 2010). An accurate diagnosis of the effects of climate change on the distributions of species requires, firstly, that methods used for detection of distributional changes are able to distinguish between directional and non-directional changes and, secondly, that they are able to tease apart distributional changes driven by natural population dynamics from changes driven by external forcing (climatic or non-climatic). We ask how appropriate are methods commonly used to detect directional shifts on species range changes. We compare a widely used range-shift detection method previously used to demonstrate that climate change caused British breeding bird distributions to move northwards with alternative approaches that more comprehensively examine directionality in range changes. We find that once range dynamics are examined across all geographical quadrants in Britain, and in contrast with previous reports, no clear directional patterns of range shift emerge for this period. Some of the methods typically used for examining species range shifts are prone to false positive errors, whereby directional range shifts are detected when in fact they did not occur. Without entering the discussion of what is more important to avoid (false negative errors, whereby directional range shifts pass unnoticed by analysis, or false positive errors), we argue that methods exist to determine whether range changes are directional or non-directional (a prerequisite to discern the causes of range changes).

Emergent Rainy Winter Warm Spells May Promote Boreal Predator Expansion into the Arctic

Climate change has been characterized as the most serious threat to Arctic biodiversity. In addition to gradual changes such as climate warming, extreme weather events, such as melting temperatures in winter and rain on snow, can have profound consequences for ecosystems. Rain-on-snow events lead to the formation of ice layers in the snow pack, which can restrict access to forage plants and cause crashes of herbivore populations. These direct impacts can have cascading effects on other ecosystem components, often mediated by trophic interactions. Here we document how heavy rain in early winter, leading to the formation of a thick layer of ice, was associated with dramatic mortality of domestic reindeer on Yamal Peninsula, Russia. In the subsequent summer, breeding of two boreal generalist predators, red fox and Hooded Crow, was recorded for the first time in a monitoring area in the Low Arctic tundra of this region. We suggest that the resource pulse created by the abnormally high reindeer mortality and abundance of carrion may have facilitated these breeding events north of the known breeding range of the two species. Our observations provide an example of how specific emergent weather events may indirectly pave the way for more abrupt, although possibly temporary, species range changes.

Disturbance and climate microrefugia mediate tree range shifts during climate change

Many tree species will shift their distribution as the climate continues to change. To assess species’ range changes, modeling efforts often rely on climatic predictors, sometimes incorporating biotic interactions (e.g. competition or facilitation), but without integrating topographic complexity or the dynamics of disturbance and forest succession. We investigated the role of ‘safe islands’ of establishment (“microrefugia”) in conjunction with disturbance and succession, on mediating range shifts. We simulated eight tree species and multiple disturbances across an artificial landscape designed to highlight variation in topographic complexity. Specifically, we simulated spatially explicit successional changes for a 100-year period of climate warming under different scenarios of disturbance and climate microrefugia. Disturbance regimes play a major role in mediating species range changes. The effects of disturbance range from expediting range contractions for some species to facilitating colonization of new ranges for others. Microrefugia generally had a significant but smaller effect on range changes. The existence of microrefugia could enhance range persistence but implies increased environmental heterogeneity, thereby hampering migration under some disturbance regimes and for species with low dispersal capabilities. Species that gained suitable habitat due to climate change largely depended on the interaction between species life history traits, environmental heterogeneity and disturbance regimes to expand their ranges. Disturbance and microrefugia play a key role in determining forest range shifts during climate change. The study highlights the urgent need of including non-deterministic successional pathways into climate change projections of species distributions.

Habitat-specific effects of climate change on a low-mobility Arctic spider species

Terrestrial ecosystems are heterogeneous habitat mosaics of varying vegetation types that are differentially affected by climate change. Arctic plant communities, for example, are changing faster in moist habitats than in dry habitats and abiotic changes like snowmelt vary locally among habitats. Such differences between habitats may influence the effects of climate changes on animals and this could be especially true in low-mobility species. Suitable model systems to test this idea, however, are rare. We examined how proxies of reproductive success (body size, juvenile/female ratios) and sex ratios have changed in low-mobility crab spiders collected systematically over a 17-year period (1996–2012) from two distinct habitats (mesic and arid dwarf shrub heath) at Zackenberg in northeast Greenland. We identified all adults in the collection to confirm that they represented just one species (Xysticus deichmanni Sorensen) based on morphology. This provided a unique opportunity to measure recruitment potential because we could assume that all juvenile crab spiders belonged to that species. We determined sex, stage, and size of all specimens (n = 2,115). Body size variation was significantly related to the timing of snowmelt and differed significantly between the sexes and habitats with the spiders in the mesic habitat showing a stronger temporal response to later snowmelt. Juvenile/female ratios also differed significantly between habitats; as did the overall abundance of individuals. We found significant main effects of snowmelt and habitat on sex ratio with the proportion of females decreasing significantly in response to later snowmelt only in the mesic sites. Effects of climate change may be masked by habitat differences and have implications for future range changes of species at both small and large spatial extents. We recommend that local habitat differences are included in analyses of species responses to climate change.