Adaptive population divergence and directional gene flow across steep elevational gradients in a climate‐sensitive mammal

The ecological effects of climate change have been shown in most major taxonomic groups; however, the evolutionary consequences are less well‐documented. Adaptation to new climatic conditions offers a potential long‐term mechanism for species to maintain viability in rapidly changing environments, but mammalian examples remain scarce. The American pika (Ochotona princeps) has been impacted by recent climate‐associated extirpations and range‐wide reductions in population sizes, establishing it as a sentinel mammalian species for climate change. To investigate evidence for local adaptation and reconstruct patterns of genomic diversity and gene flow across rapidly changing environments, we used a space‐for‐time design and restriction site‐associated DNA sequencing to genotype American pikas along two steep elevational gradients at 30,966 SNPs and employed independent outlier detection methods that scanned for genotype‐environment associations. We identified 338 outlier SNPs detected by two separate analyses and/or replicated in both transects, several of which were annotated to genes involved in metabolic function and oxygen transport. Additionally, we found evidence of directional gene flow primarily downslope from high‐elevation populations, along with reduced gene flow at outlier loci. If this trend continues, elevational range contractions in American pikas will likely be from local extirpation rather than upward movement of low‐elevation individuals; this, in turn, could limit the potential for adaptation within this landscape. These findings are of particular relevance for future conservation and management of American pikas and other elevationally restricted, thermally sensitive species.     

Climate‐niche factor analysis: a spatial approach to quantifying species vulnerability to climate change

Climate change vulnerability assessments are an important tool for understanding the threat that climate change poses to species and populations, but do not generally yield insight into the spatial variation in vulnerability throughout a species’ habitat. We demonstrate how to adapt the method of ecological‐niche factor analysis (ENFA) to objectively quantify aspects of species sensitivity to climate change. We then expand ENFA to quantify aspects of exposure and vulnerability to climate change as well, using future projections of global climate models. This approach provides spatially‐explicit insight into geographic patterns of vulnerability, relies only on readily‐available spatial data, is suitable for a wide range of species and habitats, and invites comparison between different species. We apply our methods to a case study of two species of montane mammals, the American pika Ochotona princeps and the yellow‐bellied marmot Marmota flaviventris.     

Adaptive divergence along environmental gradients in a climate‐change‐sensitive mammal

In the face of predicted climate change, a broader understanding of biotic responses to varying environments has become increasingly important within the context of biodiversity conservation. Local adaptation is one potential option, yet remarkably few studies have harnessed genomic tools to evaluate the efficacy of this response within natural populations. Here, we show evidence of selection driving divergence of a climate‐change‐sensitive mammal, the American pika (Ochotona princeps), distributed along elevation gradients at its northern range margin in the Coast Mountains of British Columbia (BC), Canada. We employed amplified‐fragment‐length‐polymorphism‐based genomic scans to conduct genomewide searches for candidate loci among populations inhabiting varying environments from sea level to 1500 m. Using several independent approaches to outlier locus detection, we identified 68 candidate loci putatively under selection (out of a total 1509 screened), 15 of which displayed significant associations with environmental variables including annual precipitation and maximum summer temperature. These candidate loci may represent important targets for predicting pika responses to climate change and informing novel approaches to wildlife conservation in a changing world.     

An empirical test of the relative and combined effects of land‐cover and climate change on local colonization and extinction

Land‐cover and climate change are two main drivers of changes in species ranges. Yet, the majority of studies investigating the impacts of global change on biodiversity focus on one global change driver and usually use simulations to project biodiversity responses to future conditions. We conduct an empirical test of the relative and combined effects of land‐cover and climate change on species occurrence changes. Specifically, we examine whether observed local colonization and extinctions of North American birds between 1981–1985 and 2001–2005 are correlated with land‐cover and climate change and whether bird life history and ecological traits explain interspecific variation in observed occurrence changes. We fit logistic regression models to test the impact of physical land‐cover change, changes in net primary productivity, winter precipitation, mean summer temperature, and mean winter temperature on the probability of Ontario breeding bird local colonization and extinction. Models with climate change, land‐cover change, and the combination of these two drivers were the top ranked models of local colonization for 30%, 27%, and 29% of species, respectively. Conversely, models with climate change, land‐cover change, and the combination of these two drivers were the top ranked models of local extinction for 61%, 7%, and 9% of species, respectively. The quantitative impacts of land‐cover and climate change variables also vary among bird species. We then fit linear regression models to test whether the variation in regional colonization and extinction rate could be explained by mean body mass, migratory strategy, and habitat preference of birds. Overall, species traits were weakly correlated with heterogeneity in species occurrence changes. We provide empirical evidence showing that land‐cover change, climate change, and the combination of multiple global change drivers can differentially explain observed species local colonization and extinction.     

Predicting potential responses to future climate in an alpine ungulate: interspecific interactions exceed climate effects

The altitudinal shifts of many montane populations are lagging behind climate change. Understanding habitual, daily behavioural rhythms, and their climatic and environmental influences, could shed light on the constraints on long‐term upslope range‐shifts. In addition, behavioural rhythms can be affected by interspecific interactions, which can ameliorate or exacerbate climate‐driven effects on ecology. Here, we investigate the relative influences of ambient temperature and an interaction with domestic sheep (Ovis aries) on the altitude use and activity budgets of a mountain ungulate, the Alpine chamois (Rupicapra rupicapra). Chamois moved upslope when it was hotter but this effect was modest compared to that of the presence of sheep, to which they reacted by moving 89–103 m upslope, into an entirely novel altitudinal range. Across the European Alps, a range‐shift of this magnitude corresponds to a 46% decrease in the availability of suitable foraging habitat. This highlights the importance of understanding how factors such as competition and disturbance shape a given species’ realised niche when predicting potential future responses to change. Furthermore, it exposes the potential for manipulations of species interactions to ameliorate the impacts of climate change, in this case by the careful management of livestock. Such manipulations could be particularly appropriate for species where competition or disturbance already strongly restricts their available niche. Our results also reveal the potential role of behavioural flexibility in responses to climate change. Chamois reduced their activity when it was warmer, which could explain their modest altitudinal migrations. Considering this behavioural flexibility, our model predicts a small 15–30 m upslope shift by 2100 in response to climate change, less than 4% of the altitudinal shift that would be predicted using a traditional species distribution model‐type approach (SDM), which assumes that species’ behaviour remains unchanged as climate changes. Behavioural modifications could strongly affect how species respond to a changing climate.     

Re-assessing current extinction rates

There is a widespread belief that we are experiencing a mass extinction event similar in severity to previous mass extinction events in the last 600 million years where up to 95% of species disappeared. This paper reviews evidence for current extinctions and different methods of assessing extinction rates including species–area relationships and loss of tropical forests, changing threat status of species, co-extinction rates and modelling the impact of climate change. For 30 years some have suggested that extinctions through tropical forest loss are occurring at a rate of up to 100 species a day and yet less than 1,200 extinctions have been recorded in the last 400 years. Reasons for low number of identified global extinctions are suggested here and include success in protecting many endangered species, poor monitoring of most of the rest of species and their level of threat, extinction debt where forests have been lost but species still survive, that regrowth forests may be important in retaining ‘old growth’ species, fewer co-extinctions of species than expected, and large differences in the vulnerability of different taxa to extinction threats. More recently, others have suggested similar rates of extinction to earlier estimates but with the key cause of extinction being climate change, and in particular rising temperatures, rather than deforestation alone. Here I suggest that climate change, rather than deforestation is likely to bring about such high levels of extinction since the impacts of climate change are local to global and that climate change is acting synergistically with a range of other threats to biodiversity including deforestation.     

Mechanistic variables can enhance predictive models of endotherm distributions: the American pika under current,past, and future climates

How climate constrains species’ distributions through time and space is an important question in the context of conservation planning for climate change. Despite increasing awareness of the need to incorporate mechanism into species distribution models (SDMs), mechanistic modeling of endotherm distributions remains limited in this literature. Using the American pika (Ochotona princeps) as an example, we present a framework whereby mechanism can be incorporated into endotherm SDMs. Pika distribution has repeatedly been found to be constrained by warm temperatures, so we used Niche Mapper, a mechanistic heat‐balance model, to convert macroclimate data to pika‐specific surface activity time in summer across the western United States. We then explored the difference between using a macroclimate predictor (summer temperature) and using a mechanistic predictor (predicted surface activity time) in SDMs. Both approaches accurately predicted pika presences in current and past climate regimes. However, the activity models predicted 8–19% less habitat loss in response to annual temperature increases of ~3–5 °C predicted in the region by 2070, suggesting that pikas may be able to buffer some climate change effects through behavioral thermoregulation that can be captured by mechanistic modeling. Incorporating mechanism added value to the modeling by providing increased confidence in areas where different modeling approaches agreed and providing a range of outcomes in areas of disagreement. It also provided a more proximate variable relating animal distribution to climate, allowing investigations into how unique habitat characteristics and intraspecific phenotypic variation may allow pikas to exist in areas outside those predicted by generic SDMs. Only a small number of easily obtainable data are required to parameterize this mechanistic model for any endotherm, and its use can improve SDM predictions by explicitly modeling a widely applicable direct physiological effect: climate‐imposed restrictions on activity. This more complete understanding is necessary to inform climate adaptation actions, management strategies, and conservation plans.     

Impacts of climate warming and habitat loss on extinctions at species' low-latitude range boundaries

Polewards expansions of species' distributions have been attributed to climate warming, but evidence for climate‐driven local extinctions at warm (low latitude/elevation) boundaries is equivocal. We surveyed the four species of butterflies that reach their southern limits in Britain. We visited 421 sites where the species had been recorded previously to determine whether recent extinctions were primarily due to climate or habitat changes. Coenonympha tullia had become extinct at 52% of study sites and all losses were associated with habitat degradation. Aricia artaxerxes was extinct from 50% of sites, with approximately one‐third to half of extinctions associated with climate‐related factors and the remainder with habitat loss. For Erebia aethiops (extinct from 24% of sites), approximately a quarter of the extinctions were associated with habitat and three‐quarters with climate. For Erebia epiphron, extinctions (37% of sites) were attributed mainly to climate with almost no habitat effects. For the three species affected by climate, range boundaries retracted 70–100 km northwards (A. artaxerxes, E. aethiops) and 130–150 m uphill (E. epiphron) in the sample of sites analysed. These shifts are consistent with estimated latitudinal and elevational temperature shifts of 88 km northwards and 98 m uphill over the 19‐year study period. These results suggest that the southern/warm range margins of some species are as sensitive to climate change as are northern/cool margins. Our data indicate that climate warming has been of comparable importance to habitat loss in driving local extinctions of northern species over the past few decades; future climate warming is likely to jeopardize the long‐term survival of many northern and mountain species.     

Integrating ecophysiological models into species distribution projections of European reptile range shifts in response to climate change

Uncertainty in projections of global change impacts on biodiversity over the 21st century is high. Improved predictive accuracy is needed, highlighting the importance of using different types of models when predicting species range shifts. However, this is still rarely done. Our approach integrates the outputs of a spatially‐explicit physiologically inspired model of extinction and correlative species distribution models to assess climate‐change induced range shifts of three European reptile species (Lacerta lepida, Iberolacerta monticola, and Hemidactylus turcicus) in the coming decades. We integrated the two types of models by mapping and quantifying agreement and disagreement between their projections. We analyzed the relationships between climate change and projected range shifts. Agreement between model projections varied greatly between species and depended on whether or not they consider dispersal ability. Under our approach, the reliability of predictions is greatest where the predictions of these different types of models converge, and in this way uncertainty is reduced; sites where this convergence occurs are characterized by both current high temperatures and significant future temperature increase, suggesting they may become hotspots of local extinctions. Moreover, this approach can be readily implemented with other types of models.     

Climate Tolerances and Habitat Requirements Jointly Shape the Elevational Distribution of the American Pika (Ochotona princeps), with Implications for Climate Change Effects

Some of the most compelling examples of ecological responses to climate change are elevational range shifts of individual species, which have been observed throughout the world. A growing body of evidence, however, suggests substantial mediation of simple range shifts due to climate change by other limiting factors. Understanding limiting factors for a species within different contexts, therefore, is critical for predicting responses to climate change. The American pika (Ochotona princeps) is an ideal species for investigating distributions in relation to climate because of their unusual and well-understood natural history as well as observed shifts to higher elevation in parts of their range. We tested three hypotheses for the climatic or habitat characteristics that may limit pika presence and abundance: summer heat, winter snowpack, and forage availability. We performed these tests using an index of pika abundance gathered in a region where environmental influences on pika distribution have not been well-characterized. We estimated relative pika abundance via scat surveys and quantified climatic and habitat characteristics across two North-Central Rocky Mountain Ranges, the Wind River and Bighorn ranges in Wyoming, USA. Pika scat density was highest at mid-elevations and increased linearly with forage availability in both ranges. Scat density also increased with temperatures conducive to forage plant growth, and showed a unimodal relationship with the number of days below -5°C, which is modulated by insulating snowpack. Our results provide support for both the forage availability and winter snowpack hypotheses. Especially in montane systems, considering the context-dependent nature of climate effects across regions and elevations as well as interactions between climatic and other critical habitat characteristics, will be essential for predicting future species distributions.     

Differential effects of temperature change and human impact on European Late Quaternary mammalian extinctions

Species that inhabited Europe during the Late Quaternary were impacted by temperature changes and early humans, resulting in the disappearance of half of the European large mammals. However, quantifying the relative importance that each factor had in the extinction risk of species has been challenging, mostly due to the spatio‐temporal biases of fossil records, which complicate the calibration of realistic and accurate ecological niche modeling. Here, we overcome this problem by using ecotypes, and not real species, to run our models. We created 40 ecotypes with different temperature requirements (mean temperature from ?20 °C to 25 °C and temperature range from 10 °C to 40 °C) and used them to quantify the effect of climate change and human impact. Our results show that cold‐adapted ecotypes would have been highly affected by past temperature changes in Europe, whereas temperate and warm‐adapted ecotypes would have been positively affected by temperature change. Human impact affected all ecotypes negatively, and temperate ecotypes suffered the greatest impacts. Based on these results, the extinction of cold‐adapted species like Mammuthus primigenius may be related to temperature change, while the extinction of temperate species, like Crocuta crocuta, may be related to human impact. Our results suggest that temperature change and human impact affected different ecotypes in distinct ways, and that the interaction of both impacts may have shaped species extinctions in Europe.     

Upslope Range Shifts of Andean Dung Beetles in Response to Deforestation: Compounding and Confounding Effects of Microclimatic Change

Warmer, and sometimes drier, conditions associated with global climate change are driving many species to shift poleward and/or upslope. I hypothesized that microclimatic changes related to deforestation cause similar shifts for forest species persisting within degraded landscapes. This appears to be the first study to examine this novel hypothesis. I examined elevational distributions of dung beetle communities along parallel intact and disturbed elevational gradients from 290 to 3450 m asl in the Andes of southeastern Peru. Deforested sites were consistently warmer and drier than forested sites. To maintain the same ambient temperature as in forest, species in a deforested landscape would need to shift on average 489±59 m upslope. Dung beetle species showed a mean upslope range shift of 132±64 m (maximum=743 m) in the deforested landscape. Eight species occurred farther upslope in the degraded landscape, while none shifted downslope. In addition to upper range limit expansions, six species shifting upslope also showed range contractions or population declines at their lower range boundary. High elevation and disturbance‐tolerant species did not show range shifts. These findings suggest that land‐use change may both confound and compound the influence of global climate change on biodiversity. Synergies between habitat degradation and climate change could more than double previous range shift projections for this century, leading to unexpectedly rapid changes in biodiversity, especially for sensitive organisms such as tropical insects. On the other hand, range shifts caused by habitat degradation may be mistakenly attributed to global climate change. Abstract in Spanish is available in the online version of this article.     

A brief history of Great Basin pikas

Aim Within the past few decades, seven of the 25 historically described populations of American pikas (Ochotona princeps) in the Great Basin of arid western North America appear to have become extinct. In this paper, the prehistoric record for pikas in the Great Basin is used to place these losses in deeper historical context. Location The Great Basin, or area of internal drainage, of the western United States. Methods The location, elevation, and age of all reported prehistoric Great Basin specimens of American pikas were extracted from the literature. Elevations of extinct pika populations were arrayed through time, and latitudes and longitudes of those populations used to determine changing distances of those populations from the nearest extant populations. Results The average elevation of now‐extinct Great Basin pika populations during the late Wisconsinan (c. 40,000–10,000 radiocarbon years ago) and early Holocene (c. 10,000–7500 years ago) was 1750 m. During the hot and dry middle Holocene (c. 7500–4500 years ago), the average elevation of these populations rose 435 m, to 2168 m. All prehistorically known late Holocene (c. 4500–200 years ago) populations in the Great Basin are from mountain ranges that currently support populations of this animal, but historic period losses have caused the average elevation of pika populations to rise an additional 152 m. The total elevational increase, from the late Wisconsinan and early Holocene to today, has been 783 m. As lower elevation pika populations were lost, their distribution increasingly came to resemble its modern form. During the late Wisconsinan, now‐extinct pika populations were located an average of 170 km from the nearest extant population. By the late Holocene, this distance had declined to 30 km. Main conclusions Prehistoric alterations in the distribution of pika population in the Great Basin were driven by climate change and attendant impacts on vegetation. Today, Great Basin pikas contend with both climate change and anthropogenic impacts and thus may be on the brink of extinction.     

Niche width predicts extinction from climate change and vulnerability of tropical species

Climate change may be a major threat to global biodiversity, especially to tropical species. Yet, why tropical species are more vulnerable to climate change remains unclear. Tropical species are thought to have narrower physiological tolerances to temperature, and they have already experienced a higher estimated frequency of climate-related local extinctions. These two patterns suggest that tropical species are more vulnerable to climate change because they have narrower thermal niche widths. However, no studies have tested whether species with narrower climatic niche widths for temperature have experienced more local extinctions, and if these narrower niche widths can explain the higher frequency of tropical local extinctions. Here, we test these ideas using resurvey data from 538 plant and animal species from 10 studies. We found that mean niche widths among species and the extent of climate change (increase in maximum annual temperatures) together explained most variation (>75%) in the frequency of local extinction among studies. Surprisingly, neither latitude nor occurrence in the tropics alone significantly predicted local extinction among studies, but latitude and niche widths were strongly inversely related. Niche width also significantly predicted local extinction among species, as well as among and (sometimes) within studies. Overall, niche width may offer a relatively simple and accessible predictor of the vulnerability of populations to climate change. Intriguingly, niche width has the best predictive power to explain extinction from global warming when it incorporates coldest yearly temperatures.     

Not‐so‐splendid isolation: modeling climate‐mediated range collapse of a montane mammal Ochotona princeps across numerous ecoregions

We modeled current and future distribution of suitable habitat for the talus‐obligate montane mammal Ochotona princeps (American pika) across the western USA under increases in temperature associated with contemporary climate change, to: a) compare forecasts using only climate variables vs using those plus habitat considerations; b) identify possible patterns of range collapse (center vs margins, and large‐ vs small‐sized patches); and c) compare conservation and management implications of changes at two taxonomic resolutions, and using binned‐ vs binary‐probability maps. We used MaxEnt to analyze relationships between occurrence records and climatic variables to develop a bioclimatic‐envelope model, which we refined by masking with a deductive appropriate‐habitat filter based on suitable land‐cover types. We used this final species‐distribution model to predict distribution of suitable habitat under range‐wide temperature increases from 1 to 7°C, in 1°C increments; we also compared these results to distribution under IPCC‐forecasted climates for 2050 and 2080. Though all currently recognized lineages and traditionally defined subspecies were predicted to lose increasing amounts of habitat as temperatures rose, the most‐dramatic range losses were predicted to occur among traditional subspecies. Nineteen of the 31 traditional US pika subspecies were predicted to lose > 98% of their suitable habitat under a 7?C increase in the mean temperature of the warmest quarter of the year, and lineages were predicted to lose 88 95% of suitable habitat. Under a 4?C increase, traditional subspecies averaged a predicted 73% (range = 44–99%) reduction. The appropriate‐habitat filter removed 40–6% of the predicted climatically suitable pixels, in a stepped and monotonically decreasing fashion as predicted temperatures rose. Predicted range collapse proceeded until only populations in island‐biogeographic ‘mainlands’ remained, which were not in the geographic range center. We used this model system to illustrate possible distributional shifts under stepped changes in biologically relevant aspects of climate, importance of land cover and taxonomic level in species‐distribution forecasts, and impact of using a single threshold vs multiple categories of persistence probability in predicted range maps; we encourage additional research to further investigate the generality of these patterns.     

Combination of humans,climate, and vegetation change triggered Late Quaternary megafauna extinction in the Última Esperanza region,southern Patagonia,Chile

South America lost around 52 genera of mammals during a worldwide event known as the Late Quaternary Extinction episode. More than 80% of South American mammals weighing > 44 kg succumbed. Analysis of the megafaunal extinction chronology in relation to human arrival and major climate changes have revealed slightly different extinction patterns in different eco‐regions of the continent, highlighting the importance of detailed regional analysis in order to understand how the possible drivers of extinction operated. Here we present an analysis of the megafaunal extinction in the Última Esperanza (UE) area of southwestern Patagonia, Chile. We have compiled a comprehensive chronology of megafaunal extinctions and earliest human occupation between 18–7 cal ka BP, based on radiocarbon dates from published literature. We calculated confidence intervals using the GRIWM method to estimate the times of human arrival and megafaunal local extinctions, and then compared these events to the timing of major climate and vegetation changes, fire frequency increase, and the Reclús volcanic eruption. Our results suggest that a combination of human impacts and climate–vegetation change drove megafaunal extinctions in the UE area, with the balance of factors being taxon specific; the volcanic eruption does not seem to have exacerbated extinctions. Competition between humans and mega‐carnivores seems to be the most plausible cause for the extinction of the mega‐carnivores. Coexistence of humans with extinct horses, extinct camels, and mylodonts for several thousand years rules out a scenario of blitzkrieg overkill of megafauna by humans. The transition of vegetation from cold grasslands to Nothofagus forests corresponds with the disappearance of Hippidion saldiasi and Lama cf. owenii. The later full establishment of Nothofagus forests and an increasing fire frequency coincided with the disappearance of mylodonts. A climate‐driven reduction of open environments plausibly reduced herbivore's populations making them susceptible to local extinction.     

Extinction‐driven changes in frugivore communities on oceanic islands

Global change and human expansion have resulted in many species extinctions worldwide, but the geographic variation and determinants of extinction risk in particular guilds still remain little explored. Here, we quantified insular extinctions of frugivorous vertebrates (including birds, mammals and reptiles) across 74 tropical and subtropical oceanic islands within 20 archipelagos worldwide and investigated extinction in relation to island characteristics (island area, isolation, elevation and climate) and species’ functional traits (body mass, diet and ability to fly). Out of the 74 islands, 33 islands (45%) have records of frugivore extinctions, with one third (mean: 34%, range: 2–100%) of the pre‐extinction frugivore community being lost. Geographic areas with more than 50% loss of pre‐extinction species richness include islands in the Pacific (within Hawaii, Cook Islands and Tonga Islands) and the Indian Ocean (Mascarenes, Seychelles). The proportion of species richness lost from original pre‐extinction communities is highest on small and isolated islands, increases with island elevation, but is unrelated to temperature or precipitation. Large and flightless species had higher extinction probability than small or volant species. Across islands with extinction events, a pronounced downsizing of the frugivore community is observed, with a strong extinction‐driven reduction of mean body mass (mean: 37%, range: –18–100%) and maximum body mass (mean: 51%, range: 0–100%). The results document a substantial trophic downgrading of frugivore communities on oceanic islands worldwide, with a non‐random pattern in relation to geography, island characteristics and species’ functional traits. This implies severe consequences for ecosystem processes that depend on mutualistic plant–animal interactions, including ecosystem dynamics that result from the dispersal of large‐seeded plants by large‐bodied frugivores. We suggest that targeted conservation and rewilding efforts on islands are needed to halt the defaunation of large and non‐volant seed dispersers and to restore frugivore communities and key ecological interactions.     

Landscape effects on gene flow for a climate‐sensitive montane species,the American pika

Climate change is arguably the greatest challenge to conservation of our time. Most vulnerability assessments rely on past and current species distributions to predict future persistence but ignore species' abilities to disperse through landscapes, which may be particularly important in fragmented habitats and crucial for long‐term persistence in changing environments. Landscape genetic approaches explore the interactions between landscape features and gene flow and can clarify how organisms move among suitable habitats, but have suffered from methodological uncertainties. We used a landscape genetic approach to determine how landscape and climate‐related features influence gene flow for American pikas (Ochotona princeps) in Crater Lake National Park. Pikas are heat intolerant and restricted to cool microclimates; thus, range contractions have been predicted as climate changes. We evaluated the correlation between landscape variables and genetic distance using partial Mantel tests in a causal modelling framework, and used spatially explicit simulations to evaluate methods of model optimization including a novel approach based on relative support and reciprocal causal modelling. We found that gene flow was primarily restricted by topographic relief, water and west‐facing aspects, suggesting that physical restrictions related to small body size and mode of locomotion, as well as exposure to relatively high temperatures, limit pika dispersal in this alpine habitat. Our model optimization successfully identified landscape features influencing resistance in the simulated data for this landscape, but underestimated the magnitude of resistance. This is the first landscape genetic study to address the fundamental question of what limits dispersal and gene flow in the American pika.     

Managed relocation as an adaptation strategy for mitigating climate change threats to the persistence of an endangered lizard

The distributional ranges of many species are contracting with habitat conversion and climate change. For vertebrates, informed strategies for translocations are an essential option for decisions about their conservation management. The pygmy bluetongue lizard, Tiliqua adelaidensis, is an endangered reptile with a highly restricted distribution, known from only a small number of natural grassland fragments in South Australia. Land‐use changes over the last century have converted perennial native grasslands into croplands, pastures and urban areas, causing substantial contraction of the species' range due to loss of essential habitat. Indeed, the species was thought to be extinct until its rediscovery in 1992. We develop coupled‐models that link habitat suitability with stochastic demographic processes to estimate extinction risk and to explore the efficacy of potential climate adaptation options. These coupled‐models offer improvements over simple bioclimatic envelope models for estimating the impacts of climate change on persistence probability. Applying this coupled‐model approach to T. adelaidensis, we show that: (i) climate‐driven changes will adversely impact the expected minimum abundance of populations and could cause extinction without management intervention, (ii) adding artificial burrows might enhance local population density, however, without targeted translocations this measure has a limited effect on extinction risk, (iii) managed relocations are critical for safeguarding lizard population persistence, as a sole or joint action and (iv) where to source and where to relocate animals in a program of translocations depends on the velocity, extent and nonlinearities in rates of climate‐induced habitat change. These results underscore the need to consider managed relocations as part of any multifaceted plan to compensate the effects of habitat loss or shifting environmental conditions on species with low dispersal capacity. More broadly, we provide the first step towards a more comprehensive framework for integrating extinction risk, managed relocations and climate change information into range‐wide conservation management.