Undergoing Range Expansion Research Articles

Inside dynamics for stage-structured integrodifference equations.

A stage-structured model of integrodifference equations is used to study the asymptotic neutral genetic structure of populations undergoing range expansion. That is, we study the inside dynamics of solutions to stage-structured integrodifference equations. To analyze the genetic consequences for long term population spread, we decompose the solution into neutral genetic components called neutral fractions. The inside dynamics are then given by the spatiotemporal evolution of these neutral fractions. We show that, under some mild assumptions on the dispersal kernels and population projection matrix, the spread is dominated by individuals at the leading edge of the expansion. This result is consistent with the founder effect. In the case where there are multiple neutral fractions at the leading edge we are able to explicitly calculate the asymptotic proportion of these fractions found in the long-term population spread. This formula is simple and depends only on the right and left eigenvectors of the population projection matrix evaluated at zero and the initial proportion of each neutral fraction at the leading edge of the range expansion. In the absence of a strong Allee effect, multiple neutral fractions can drive the long-term population spread, a situation not possible with the scalar model.

Genetic swamping and possible species collapse: tracking introgression between the native Candy Darter and introduced Variegate Darter

Candy Darters (Etheostoma osburni) and Variegate Darters (E. variatum) are both native to West Virginia and Virginia. The geographic ranges of these two species were historically separated by Kanawha Falls, a natural barrier to fish dispersal located at Glen Ferris, WV. In the early 1980s, Variegate Darters or putative hybrids (E. osburni × E. variatum) were first collected at locations upstream of Kanawha Falls, and have since undergone range expansion. Hybridization with the Variegate Darter was one of the threats that led to the Candy Darter being listed as Endangered under the U.S. Endangered Species Act in 2018. Genetic and morphologic data were examined for individuals from the New, Gauley, and Greenbrier river drainages. Individuals were genotyped using a suite of 5 diagnostic microsatellite loci to investigate potential hybridization. Widespread hybridization was found throughout populations of Candy Darters, with the geographic range of hybridization expanding from 2004 to 2014. A hybrid zone was observed, with the highest levels of Variegate Darter introgression representing the kernel within this zone and the locations of first-generation (F1) hybrids at the periphery. F1 hybrids were morphologically intermediate within and across characters for parental species. Introgressive hybridization threatens the genetic integrity of the Candy Darter, and may lead to population extirpation or extinction.

Is the future already here? The impact of climate change on the distribution of the eastern coral snake (Micrurus fulvius).

Anthropogenic climate change is a significant global driver of species distribution change. Although many species have undergone range expansion at their poleward limits, data on several taxonomic groups are still lacking. A common method for studying range shifts is using species distribution models to evaluate current, and predict future, distributions. Notably, many sources of ‘current’ climate data used in species distribution modeling use the years 1950–2000 to calculate climatic averages. However, this does not account for recent (post 2000) climate change. This study examines the influence of climate change on the eastern coral snake (Micrurus fulvius). Specifically, we: (1) identified the current range and suitable environment of M. fulvius in the Southeastern United States, (2) investigated the potential impacts of climate change on the distribution of M. fulvius, and (3) evaluated the utility of future models in predicting recent (2001–2015) records. We used the species distribution modeling program Maxent and compared both current (1950–2000) and future (2050) climate conditions. Future climate models showed a shift in the distribution of suitable habitat across a significant portion of the range; however, results also suggest that much of the Southeastern United States will be outside the range of current conditions, suggesting that there may be no-analog environments in the future. Most strikingly, future models were more effective than the current models at predicting recent records, suggesting that range shifts may already be occurring. These results have implications for both M. fulvius and its Batesian mimics. More broadly, we recommend future Maxent studies consider using future climate data along with current data to better estimate the current distribution.

Combining public participatory surveillance and occupancy modelling to predict the distributional response of Ixodes scapularis to climate change

Ixodes scapularis, a known vector of Borrelia burgdorferi sensu stricto (Bbss), is undergoing range expansion in many parts of Canada. The province of New Brunswick, which borders jurisdictions with established populations of I. scapularis, constitutes a range expansion zone for this species. To better understand the current and potential future distribution of this tick under climate change projections, this study applied occupancy modelling to distributional records of adult ticks that successfully overwintered, obtained through passive surveillance. This study indicates that I. scapularis occurs throughout the southern-most portion of the province, in close proximity to coastlines and major waterways. Milder winter conditions, as indicated by the number of degree days <0 °C, was determined to be a strong predictor of tick occurrence, as was, to a lesser degree, rising levels of annual precipitation, leading to a final model with a predictive accuracy of 0.845 (range: 0.828–0.893). Both RCP 4.5 and RCP 8.5 climate projections predict that a significant proportion of the province (roughly a quarter to a third) will be highly suitable for I. scapularis by the 2080s. Comparison with cases of canine infection show good spatial agreement with baseline model predictions, but the presence of canine Borrelia infections beyond the climate envelope, defined by the highest probabilities of tick occurrence, suggest the presence of Bbss-carrying ticks distributed by long-range dispersal events. This research demonstrates that predictive statistical modelling of multi-year surveillance information is an efficient way to identify areas where I. scapularis is most likely to occur, and can be used to guide subsequent active sampling efforts in order to better understand fine scale species distributional patterns.

Effects of parasite and historic driven selection on the diversity and structure of a MHC-II gene in a small mammal species (Peromyscus leucopus) undergoing range expansion

Genetic diversity may decrease from the centre to the margin of a species distribution range due to neutral stochastic processes. Selection may also alter genetic diversity in non-neutral markers, such as genes associated with the immune system. Both neutral processes and selection on the immune system are thus expected to affect the spatial distribution of such markers, but the relative strength of each has been scarcely studied. Here, we compared the diversity of a neutral marker (mitochondrial cytochrome b) and a selected marker (DRB gene from the MHC-II), in eastern-North American populations of white-footed mice (Peromyscus leucopus), a species known for its role of main reservoir of the Lyme disease. We observed distinct phylogeographic patterns with these two markers, which may be the result of selection pressure acting upon the DRB gene. As predicted by the central marginal hypothesis, we observed a loss of neutral genetic diversity toward the margin of the species distribution. A decrease in diversity was also observed for the DRB gene, likely due to genetic drift and positive selection operated by helminth parasites. Such a loss in genetic diversity at the range margin may slow down the ongoing expansion of P. leucopus, by counterbalancing the effect of global warming on the mouse survival at higher latitude.

Molecular exploration of hidden diversity in the Indo-West Pacific sciaenid clade.

The family Sciaenidae, known as croakers or drums, is one of the largest perciform fish families. A recent multi-gene based study investigating the phylogeny and biogeography of global sciaenids revealed that the origin and early diversification of this family occurred in tropical America during the Late Oligocene—Early Miocene before undergoing range expansions to other seas including the Indo-West Pacific, where high species richness is observed. Despite this clarification of the overall evolutionary history of the family, knowledge of the taxonomy and phylogeny of sciaenid genera endemic to the Indo-West Pacific is still limited due to lack of a thorough survey of all taxa. In this study, we used DNA-based approaches to investigate the evolutionary relationships, to explore the species diversity, and to elucidate the taxonomic status of sciaenid species/genera within the Indo-West Pacific clade. Three datasets were herein built for the above objectives: the combined dataset (248 samples from 45 currently recognized species) from one nuclear gene (RAG1) and one mitochondrial gene (COI); the dataset with only RAG1 gene sequences (245 samples from 44 currently recognized species); and the dataset with only COI gene sequences (308 samples from 51 currently recognized species). The latter was primarily used for our biodiversity exploration with two different species delimitation methods (Automatic Barcode Gap Discovery, ABGD and Generalized Mixed Yule Coalescent, GMYC). The results were further evaluated with help of four supplementary criteria for species delimitation (genetic similarity, monophyly inferred from individual gene and combined data trees, geographic distribution, and morphology). Our final results confirmed the validity of 32 currently recognized species and identified several potential new species waiting for formal descriptions. We also reexamined the taxonomic status of the genera, Larimichthys, Nibea, Protonibea and Megalonibea, and suggested a revision of Nibea and proposed a new genus Pseudolarimichthys.

Macro-scale assessment of demographic and environmental variation within genetically derived evolutionary lineages of eastern hemlock (Tsuga canadensis), an imperiled conifer of the eastern United States

Eastern hemlock (Tsuga canadensis) occupies a large swath of eastern North America and has historically undergone range expansion and contraction resulting in several genetically separate lineages. This conifer is currently experiencing mortality across most of its range following infestation of a non-native insect. With the goal of better understanding the current and future conservation potential of the species, we evaluate ecological differences among populations within these genetically defined clusters, which were previously inferred using nuclear microsatellite molecular markers from 58 eastern hemlock populations. We sub-divide these clusters into four genetic zones to differentiate putative north-central, north-east and southeast (SE) and southwest evolutionary lineages in eastern hemlock. We use demographic data (relative abundance, mortality, and seedling regeneration) from the Forest Inventory Analysis program in conjunction with environmental data to model how these lineages respond to current and future climatic gradients. Ecologically meaningful relationships are explored in the intraspecific context of hemlock abundance distribution and then related to genetic variation. We also assess hemlock's colonization likelihood via a long distance dispersal model and explore its future genetic and ecological conservation potential by combining the future suitable habitats with colonization likelihoods. Results show that future habitats under climate change will markedly

Mangrove seedling freeze tolerance depends on salt marsh presence, species, salinity, and age

With increasing global average temperatures reducing the frequency and severity of freeze events, species are undergoing range expansions. As a result, mangroves are expanding into higher latitudes previously dominated by salt marsh. The success of mangroves in these new habitats may vary based on seedling temperature tolerances, seedling age, interactions with existing salt marsh habitat, and other environmental stressors. To test this, we conducted three experiments on interactions between mangrove seedlings (Rhizophora mangle, Avicennia germinans, and Laguncularia racemosa) (1 and 6 months old) and salt marsh species (Distichlis spicata and Salicornia virginica) under varying freeze occurrence and duration (0, 1, and 4 h at −5°C) across varying salinity gradients (5, 20, and 40 PSU). Laguncularia racemosa was the most susceptible to freezing conditions, followed by R. mangle and A. germinans at 100, 40, and 33% mortality, respectively. Salt marsh excluded A. germinans under freeze conditions, whereas L. racemosa only survived when salt marsh was present (reduced mortality by 60%). Increasing salinity showed a trend where the effects of salt marsh on A. germinans and L. racemosa were reduced and replaced, respectively, under freeze events. Age of seedlings also influenced susceptibility, where newly established seedlings were less susceptible to freeze conditions.

Neutral Genetic Patterns for Expanding Populations with Nonoverlapping Generations.

We investigate the inside dynamics of solutions to integrodifference equations to understand the genetic consequences of a population with nonoverlapping generations undergoing range expansion. To obtain the inside dynamics, we decompose the solution into neutral genetic components. The inside dynamics are given by the spatiotemporal evolution of the neutral genetic components. We consider thin-tailed dispersal kernels and a variety of per capita growth rate functions to classify the traveling wave solutions as either pushed or pulled fronts. We find that pulled fronts are synonymous with the founder effect in population genetics. Adding overcompensation to the dynamics of these fronts has no impact on genetic diversity in the expanding population. However, growth functions with a strong Allee effect cause the traveling wave solution to be a pushed front preserving the genetic variation in the population. In this case, the contribution of each neutral fraction can be computed by a simple formula dependent on the initial distribution of the neutral fractions, the traveling wave solution, and the asymptotic spreading speed.

The temporal structure of the environment may influence range expansions during climate warming.

Understanding the processes that influence range expansions during climate warming is paramount for predicting population extirpations and preparing for the arrival of non-native species. While climate warming occurs over a background of variation due to cyclical processes and irregular events, the temporal structure of the thermal environment is largely ignored when forecasting the dynamics of non-native species. Ecological theory predicts that high levels of temporal autocorrelation in the environment - relatedness between conditions occurring in close temporal proximity - will favor populations that would otherwise have an average negative growth rate by increasing the duration of favorable environmental periods. Here, we invoke such theory to explain the success of biological invasions and evaluate the hypothesis that sustained periods of high environmental temperature can act synergistically with increases in mean temperature to favor the establishment of non-native species. We conduct a 60-day field mesocosm experiment to measure the population dynamics of the non-native cladoceran zooplankter Daphnia lumholtzi and a native congener Daphnia pulex in ambient temperature environments (control), warmed with recurrent periods of high environmental temperatures (uncorrelated-warmed), or warmed with sustained periods of high environmental temperatures (autocorrelated-warmed), such that both warmed treatments exhibited the same mean temperature but exhibited different temporal structures of their thermal environments. Maximum D.lumholtzi densities in the warmed-autocorrelated treatment were threefold and eightfold higher relative to warmed-uncorrelated and control treatments, respectively. Yet, D.lumholtzi performed poorly across all experimental treatment(s) relative to D.pulex and were undetectable (by) the end of the experiment. Using mathematical models, we show that this increase in performance can occur alongside increasing temporal autocorrelation and should occur over a broad range of warming scenarios. These results provide both empirical and theoretical evidence that the temporal structure of the environment can influence the performance of species undergoing range expansions due to climate warming.

Adaptive and neutral markers both show continent-wide population structure of mountain pine beetle (Dendroctonus ponderosae).

Assessments of population genetic structure and demographic history have traditionally been based on neutral markers while explicitly excluding adaptive markers. In this study, we compared the utility of putatively adaptive and neutral single‐nucleotide polymorphisms (SNPs) for inferring mountain pine beetle population structure across its geographic range. Both adaptive and neutral SNPs, and their combination, allowed range‐wide structure to be distinguished and delimited a population that has recently undergone range expansion across northern British Columbia and Alberta. Using an equal number of both adaptive and neutral SNPs revealed that adaptive SNPs resulted in a stronger correlation between sampled populations and inferred clustering. Our results suggest that adaptive SNPs should not be excluded prior to analysis from neutral SNPs as a combination of both marker sets resulted in better resolution of genetic differentiation between populations than either marker set alone. These results demonstrate the utility of adaptive loci for resolving population genetic structure in a nonmodel organism.

Populations evolving towards failure: costs of adaptation under competition at the range edge of an invasive perennial plant

Background : Species undergoing range expansion adapt to novel and stressful environments at range fronts. These adaptations of the edge populations may incur fitness costs. These costs may play a crucial role in stopping range expansion before absolute physiological and evolutionary limits were reached. Costs however have proven to be elusive. These may be specifically expressed under competition. Aims : Here, we assessed the costs of adaptation in range-edge populations of an invasive plant by evaluating plant responses under competition. Methods : We grew plants from range-centre and edge populations under competition treatments in a glasshouse. We predicted that plants from the range-edge would express lower reproductive efficiency under competition compared with centre population plants, and this would indicate a potentially maladaptive response. Results : Under high competition, plants from the range-edge expressed lower reproductive efficiency relative to range-centre plants which supported our prediction. In addition, they were more heavily affected by competition. Conclusions : Adaptation to novel environments at the range-edge has incurred a cost as a potentially maladaptive response under competition, which may contribute to the formation of the range-edge. This finding suggests that these costs likely form part of the classic trade-offs involved with stress-tolerance and may have effects on range evolution.

Inheritance patterns of photoperiodic diapause induction inLeptinotarsa decemlineata

AbstractPhotoperiod is a reliable indicator of season and an important cue that many insects use for phenological synchronization. Undergoing range expansion insects can face a change in the local photoperiod to which they need to resynchronize. Rapid range expansion can be associated with rapid photoperiodic adaptation, which can be associated with intense selection on strongly heritable polygenic traits. Alternatively, it is proposed that, in insects with an XO sex‐determination system, genes with large effect residing on the sex chromosome could drive photoperiodic adaptation because the gene or genes are exposed to selection in the sex carrying only a single X‐chromosome. The present study seeks to understand which of these alternatives more likely explains the rapid photoperiodic adaptation in European Colorado potato beetlesLeptinotarsa decemlineataSay. Diapause induction is assessed in beetles from a northern and a southern population, as well as from reciprocal hybrid crosses between the northern and southern population, when reared at an intermediate length photoperiod. The crosses within population display the expected responses, with the northern and southern populations showing high and low diapause propensity, respectively. The hybrids show intermediate responses in all studied traits. No clear difference in the responses in hybrids depending on the latitudinal origin of their father or mother is detected, even though partial paternal line dominance is seen in the responses of male beetles in one hybrid cross. These results therefore indicate that, inL. decemlineata, photoperiodic diapause induction is strongly heritable, and has an additive polygenic autosomal background.

Species-specific differences in dynamics of agonistic interactions may contribute to the competitive advantage of the invasive signal crayfish (Pacifastacus leniusculus) over the native narrow-clawed crayfish (Astacus leptodactylus)

Species-specific differences in dynamics of agonistic interactions may influence the outcome of interspecific competition and potentially contribute to competitive advantage of one species over another. In this study, we compared the dynamics of agonistic interactions of one of the most successful crayfish invaders of European freshwater ecosystems, the signal crayfish (Pacifastacus leniusculus) and the widespread native European species currently undergoing range expansion in Croatia and Europe, the narrow-clawed crayfish (Astacus leptodactylus). Comparisons between P. leniusculus pairs and the A. leptodactylus pairs demonstrated significant differences in frequency and duration of agonistic encounters: P. leniusculus dyads engaged in fewer fights, but their duration was significantly longer. In staged interactions between size-matched interspecific pairs, agonistic behaviour of P. leniusculus individuals translated into dominance over their A. leptodactylus counterparts. This indicates that the success of P. leniusculus in agonistic encounters with the native competitor might stem from its readiness to continue fighting for a longer time period, and could lead to ecological advantages during niche competition even when facing a successful native crayfish species.

Widespread range expansions shape latitudinal variation in insect thermal limits

Research now shows that broad thermal niches observed in high-latitude ectotherms apply only to species undergoing range expansion or invasion. Non-range-expanding species are therefore unlikely to tolerate climatic warming at high latitudes. Current anthropogenic impacts, including habitat modification and climate change, may contribute to a sixth mass extinction1. To mitigate these impacts and slow further losses of biodiversity, we need to understand which species are most at risk and identify the factors contributing to current and future declines. Such information is often obtained through large-scale, comparative and biogeographic analysis of lineages or traits that are potentially sensitive to ongoing anthropogenic change—for instance to predict which regions are most susceptible to climate change-induced biodiversity loss2,3,4. However, for this approach to be generally successful, the underlying causes of identified geographical trends need to be carefully considered5. Here, I augment and reanalyse a global data set of insect thermal tolerances, evaluating the contribution of recent and contemporary range expansions to latitudinal variation in thermal niche breadth. Previous indications that high-latitude ectotherms exhibit broad thermal niches and high warming tolerances held only for species undergoing range expansions or invasions. In contrast, species with stable or declining geographic ranges exhibit latitudinally decreasing absolute thermal tolerances and no latitudinal variation in tolerance breadths. Thus, non-range-expanding species, particularly insular or endemic species, which are often of highest conservation priority, are unlikely to tolerate future climatic warming at high latitudes.

Characterizing common and range expanding species

AbstractClimate change and biological invasions have increased the likelihood of the establishment, growth, spread and survival of some species. With the recent and strongly motivated call for balanced consideration of the ecology and conservation of common and rare species, species undergoing range expansion are of particular interest. The notion of essential biodiversity variables has also re‐focussed attention on the value of abundance and occupancy observations for assessing conservation values, threats and targets – species rare or common, contracting or expanding. Changes in the distribution and abundance of common and range expanding species deserve further attention, not only to better understand their dynamics, but also as the basis for monitoring range expansions and their consequences. With the aim of characterizing range expansion, here we combine perspectives from typological approaches to studying species conservation status with perspectives from spread ecology and macroecology. Closer examination of the properties and dynamics of common species is important not only because declines in their conservation status are underappreciated, but also because those species becoming more common have significant implications for biodiversity, ecosystems and society.

Functional response comparisons among freshwater amphipods: ratio-dependence and higher predation for Gammarus pulex compared to the non-natives Dikerogammarus villosus and Echinogammarus berilloni

The invasive Ponto–Caspian amphipod Dikerogammarus villosus strongly impairs the structure of recipient freshwater communities, mostly through predation of a wide range of invertebrates. Useful insights on the ecological impact of an invader can be provided by comparing its functional response (FR)—namely the relationship between resource use and resource availability—to that of trophic analogs from the recipient communities. We applied this method and derived the FR of D. villosus, the native Gammarus pulex, and Echinogammarus berilloni, another gammarid that is also undergoing range expansion, feeding on live dipteran larvae. We tested a range of predator densities to account for mutual interference among predators, assuming that predators do not forage alone in their natural environment. We also analysed the predators’ spatial distribution to investigate whether spatial behaviour might be at the origin of interference. For the three gammarid species, the per capita predation rate was a function of the prey-to-predator ratio and showed a decelerating rise to an asymptote. There was no difference in searching efficiency between the three species while prey handling time was significantly lower in G. pulex than in D. villosus and E. berilloni, leading to a higher food intake for the native at high prey densities. Differences in morphology and behaviour between the three gammarids might explain our results. Indeed, D. villosus tended to aggregate more than the other two gammarid species, which promotes conspecific interactions. Our findings suggest that mutual interference between conspecifics is a fundamental shaper of gammarid predation. Time spent interacting with conspecifics is likely to decrease the biotic pressure of the Killer shrimp D. villosus. From a broader perspective, in addition to higher predation risk, parasitism, habitat complexity or climatic variables, the presence of conspecifics of the predator (i.e. predator density) is another factor that has the potential to alter FR comparisons.

The vulnerability of species to range expansions by predators can be predicted using historical species associations and body size.

Climate change threatens species directly through environmental changes and indirectly through its effects on species interactions. We need tools to predict which species are most vulnerable to these threats. Pairwise species associations and body size are simple but promising predictors of the relative impact of species introduced outside of their historical ranges. We examined the vulnerability of 30 fish species to the impacts of three centrarchid predators that are being introduced to lakes north of their historical range boundaries. Species that were negatively associated with each centrarchid in their historical range were more likely to be lost from lakes with centrarchid introductions. Total body length was most important in predicting impact for the most gape-limited predator. At the regional scale, our method identifies those species most vulnerable to introductions facilitated by climate change and can easily be applied to a range of taxa undergoing range expansions.

On the mismatch between salinity tolerance and preference for an invasive fish: A case for incorporating behavioral data into niche modeling

Many estuarine species are euryhaline, tolerating a broad range of salinity conditions, such that data on their salinity tolerances can provide little information about a species' distribution and abundance. This is particularly true for nonnative species, known to be tolerant of a broad range of conditions. Instead, data on a species' abiotic or habitat preferences may improve prediction of a nonnative species' potential range, if introduced or if undergoing range expansion. At minimum, information about abiotic preferences may be telling of areas where the probability of nonnative occurrence or density may be higher, and if present, of areas that confer higher fitness. In this study, the salinity preference of the nonnative African jewelfish (Hemichromis letourneuxi), a recent and rapidly-expanding invader in the Florida Everglades, was quantified in laboratory trials. Despite the broad salinity tolerance of African jewelfish (up to 50), trials show a strong preference for freshwater conditions. When presented with a salinity gradient, over 50% of observations in timed videotaped trials were collected in the lowest salinity chamber (0.3), suggesting an affinity for low salinity, which was unaffected by the sex or body condition of study fish. Fish clearly avoided mid and full salinity conditions. Findings suggest that their distribution may be considerably more limited, and that the species may have higher invasion success in oligohaline habitats, than predicted based on their salinity tolerance. Results have important implications for nonnative species niche modeling, and argue for better integration of behavior along with physiological responses when examining species distributions in dynamic environments.

Climate‐associated tundra thaw pond formation and range expansion of boreal zooplankton predators

Most of the freshwater component of the Earth's surface is composed of shallow tundra ponds. These high latitude ecosystems have been exposed to a variety of abiotic disturbances associated with recent environmental change. However, the biological significance of these changes remains poorly understood. Here, we characterize the abiotic disturbance to the shallow tundra ponds of northwest Alaska. We used historical aerial imagery to determine that up to 53% of the sampled ponds have formed during the recent warmer decades (since the 1970s). We discovered that two top predator species (phantom midges of the genus Chaoborus) of the freshwater zooplankton have recently undergone range expansion, forming widespread (a scale of hundreds of km) stable tundra populations. We assessed the population persistence of these boreal predators by longitudinal sampling over 14 yr. Recent thaw ponds had significantly dissimilar zooplankton communities to communities of ponds that formed before 1950. Both predator and herbivore species differed by age of pond. Younger pond ages and warmer surface temperatures were the significant predictors of the presence of temperate Chaoborus americanus in tundra ponds. Ponds containing tundra populations of C. americanus and C. cf. flavicans were associated with recent formation (83–90%). Recent ponds in river valleys appeared more important than recent ponds near roads as colonization corridors for C. americanus. Only 24% of the tundra keystone predator, Heterocope septentrionalis, populations were from recent ponds. Our results suggest that climate‐associated disturbance can lead to a widespread stable range expansion of boreal species despite the propinquity of older ponds with top‐down control exerted by an endemic keystone predator.