Predicted Range Expansion Research Articles

Range expansion is both slower and more variable with rapid evolution across a spatial gradient in temperature.

Rapid evolution in colonising populations can alter our ability to predict future range expansions. Recent theory suggests that the dynamics of replicate range expansions are less variable, and hence more predictable, with increased selection at the expanding range front. Here, we test whether selection from environmental gradients across space produces more consistent range expansion speeds, using the experimental evolution of replicate duckweed populations colonising landscapes with and without a temperature gradient. We found that the range expansion across a temperature gradient was slower on average, with range-front populations displaying higher population densities, and genetic signatures and trait changes consistent with directional selection. Despite this, we found that with a spatial gradient range expansion speed became more variable and less consistent among replicates over time. Our results therefore challenge current theory, highlighting that chance can still shape the genetic response to selection to influence our ability to predict range expansion speeds.

Climate match is key to predict range expansion of the world's worst invasive terrestrial vertebrates.

Understanding the determinants of the range expansion of invasive alien species is crucial for developing effective prevention and control strategies. Nevertheless, we still lack a global picture of the potential factors influencing the invaded range expansion across taxonomic groups, especially for the world's worst invaders with high ecological and economic impacts. Here, by extensively collecting data on 363 distributional ranges of 19 of world's worst invasive terrestrial vertebrates across 135 invaded administrative jurisdictions, we observed remarkable variations in the range expansion across species and taxonomic groups. After controlling for taxonomic and geographic pseudoreplicates, model averaging analyses based on generalized additive mixed-effect models showed that species in invaded regions having climates more similar to those of their native ranges tended to undergo a larger range expansion. In addition, as proxies of propagule pressure and human-assisted transportation, the number of introduction events and the road network density were also important predictors facilitating the range expansion. Further variance partitioning analyses validated the predominant role of climate match in explaining the range expansion. Our study demonstrated that regions with similar climates to their native ranges could still be prioritized to prevent the spread of invasive species under the sustained global change.

The African mosquito-borne diseasosome: geographical patterns, range expansion and future disease emergence.

Mosquito-borne diseases (MBDs) threaten public health and food security globally. We provide the first biogeographic description of the African mosquito fauna (677 species) and the 151 mosquito-borne pathogens (MBPs) they transmit. While mosquito species richness agrees with expectations based on Africa's land surface, African arboviruses and mammalian plasmodia are more speciose than expected. Species assemblages of mosquitoes and MBPs similarly separate sub-Saharan Africa from North Africa, and those in West and Central Africa from eastern and southern Africa. Similarities between mosquitoes and MBPs in diversity and range size suggest that mosquitoes are key in delimiting the range of MBPs. With approximately 25% endemicity, approximately 50% occupying one to three countries and less than 5% occupying greater than 25 countries, the ranges of mosquitoes and MBPs are surprisingly small, suggesting that most MBPs are transmitted by a single mosquito species. Exceptionally widespread mosquito species feed on people and livestock, and most are high-altitude-windborne migrants. Likewise, widespread MBPs are transmitted among people or livestock by widespread mosquitoes, suggesting that adapting to people or livestock and to widespread mosquito species promote range expansion in MBPs. Range size may predict range expansion and emergence risk. We highlight key knowledge gaps that impede prediction and mitigation of future emergence of local and global MBDs.

Understanding habitat selection of range‐expanding populations of large carnivores: 20 years of grey wolves (Canis lupus) recolonizing Germany

AbstractAimThe non‐stationarity in habitat selection of expanding populations poses a significant challenge for spatial forecasting. Focusing on the grey wolf (Canis lupus) natural recolonization of Germany, we compared the performance of different distribution modelling approaches for predicting habitat suitability in unoccupied areas. Furthermore, we analysed whether grey wolf showed non‐stationarity in habitat selection in newly colonized areas, which will impact the predictions for potential habitat.LocationGermany.MethodsUsing telemetry data as presence points, we compared the predictive performance of five modelling approaches based on combinations of distribution modelling algorithms—GLMM, MaxEnt and ensemble modelling—and two background point selection strategies. We used a homogeneous Poisson point process to draw background points from either the minimum convex polygons derived from telemetry or the whole area known to be occupied by wolves. Models were fit to the data of the first years and validated against independent data representing the expansion of the species. The best‐performing approach was then used to further investigate non‐stationarity in the species' response in spatiotemporal restricted datasets that represented different colonization steps.ResultsWhile all approaches performed similarly when evaluated against a subset of the data used to fit the models, the ensemble model based on integrated data performed best when predicting range expansion. Models for subsequent colonization steps differed substantially from the global model, highlighting the non‐stationarity of wolf habitat selection towards human disturbance during the colonization process.Main ConclusionsWhile telemetry‐only data overfitted the models, using all available datasets increased the reliability of the range expansion forecasts. The non‐stationarity in habitat selection pointed to wolves settling in the best areas first, and filling in nearby lower‐quality habitat as the population increases. Our results caution against spatial extrapolation and space‐for‐time substitutions in habitat models, at least with expanding species.

Invasive wild deer exhibit environmental niche shifts in Australia: Where to from here?

Invasive species have established populations around the world and, in the process, characteristics of their realized environmental niches have changed. Because of their popularity as a source of game, deer have been introduced to, and become invasive in, many different environments around the world. As such, deer should provide a good model system in which to test environmental niche shifts. Using the current distributions of the six deer species present in Australia, we quantified shifts in their environmental niches that occurred since introduction; we determined the differences in suitable habitat between their international (native and invaded) and their Australian ranges. Given knowledge of their Australian habitat use, we then modeled the present distribution of deer in Australia to assess habitat suitability, in an attempt to predict future deer distributions. We show that the Australian niches of hog (Axis porcinus), fallow (Dama dama), red (Cervus elaphus), rusa (C. timorensis), and sambar deer (C. unicolor), but not chital deer (A. axis), were different to their international ranges. When we quantified the potential range of these six species in Australia, chital, hog, and rusa deer had the largest areas of suitable habitat outside their presently occupied habitat. The other three species had already expanded outside the ranges that we predicted as suitable. Here, we demonstrate that deer have undergone significant environmental niche shifts following introduction into Australia, and these shifts are important for predicting the future spread of these invasive species. It is important to note that current Australian and international environmental niches did not necessarily predict range expansions, thus wildlife managers should treat these analyses as conservative estimates.

Predicting evolution in experimental range expansions of an aquatic model system.

Predicting range expansion dynamics is an important goal of both fundamental and applied research in conservation and global change biology. However, this is challenging if ecological and evolutionary processes occur on the same time scale. Using the freshwater ciliate Paramecium caudatum, we combined experimental evolution and mathematical modeling to assess the predictability of evolutionary change during range expansions. In the experiment, we followed ecological dynamics and trait evolution in independently replicated microcosm populations in range core and front treatments, where episodes of natural dispersal alternated with periods of population growth. These eco-evolutionary conditions were recreated in a predictive mathematical model, parametrized with dispersal and growth data of the 20 founder strains in the experiment. We found that short-term evolution was driven by selection for increased dispersal in the front treatment and general selection for higher growth rates in all treatments. There was a good quantitative match between predicted and observed trait changes. Phenotypic divergence was further mirrored by genetic divergence between range core and front treatments. In each treatment, we found the repeated fixation of the same cytochrome c oxidase I (COI) marker genotype, carried by strains that also were the most likely winners in our model. Long-term evolution in the experimental range front lines resulted in the emergence of a dispersal syndrome, namely a competition-colonization trade-off. Altogether, both model and experiment highlight the potential importance of dispersal evolution as a driver of range expansions. Thus, evolution at range fronts may follow predictable trajectories, at least for simple scenarios, and predicting these dynamics may be possible from knowledge of few key parameters.

Predicting the Habitat Suitability and Distribution of Two Species of Mound-Building Termites in Nigeria Using Bioclimatic and Vegetation Variables

Temperature is an important factor determining the abundance, distribution and diversity of termite species. Thus, termites are affected by changing climate and have to adopt different means of surviving in order to avoid extinction. Using termite occurrence data, bioclimatic variables and vegetation cover, we modelled and predicted the current and future habitat suitability for mound-building termites in Nigeria. Of the 19 bioclimatic variables and the vegetation index (NDVI) tested, only six were significant and eligible as predictors of habitat suitability for the mound-building termites Macrotermes subhyalinus and M. bellicosus. Under current climatic conditions (2022), the northwest, northeast and central regions are highly suitable for M. subhyalinus, while the distribution of M. bellicosus decreased in the North West, North East and in the Central region. However, regarding habitat suitability for the future (2050), there was a predicted range expansion into suitable areas for the two termite species. The increase in temperature due to global warming has an effect which can either result in migration or sometimes extinction of termite species within an ecosystem. Here, we have predicted habitat suitability for the two mound-building termite species under current and future climatic scenarios, and how the change in climatic variables would lead to an expansion in their range across Nigeria.

European beewolf (Philanthus triangulum) will expand its geographic range as a result of climate warming

Climate change is an important driver of the spread of apiary pests and honeybee predators. These impact on one of the economically most important pollinators and thus pose serious threats to the functioning of both natural ecosystems and crops. We investigated the impact of the predicted climate change in the periods 2040–2060 and 2060–2080 on the potential distribution of the European beewolf Philanthus triangulum, a specialized honeybee predator. We modelled its potential distribution using the MaxEnt method based on contemporary occurrence data and bioclimatic variables. Our model had an overall good performance (AUC = 0.864) and the threshold of occurrence probability, assessed as the point with the highest sum of sensitivity and specificity, was at 0.533. Annual temperature range (69.5%), mean temperature in the warmest quarter (12.4%), and precipitation in the warmest quarter (7.9%) were the principal bioclimatic variables significantly affecting the potential distribution of the European beewolf. We predicted the potential distribution shifts within two scenarios (optimistic RPC4.5 and pessimistic RCP8.5) and three Global Circulation Models (HadGEM2-ES, IPSL-CM5A-LR, and MPI-SM-LR). Both optimistic and pessimistic scenarios showed that climate change will significantly increase the availability of European beewolf potential niches. Losses of potential niches will only affect small areas in southern Europe. Most of the anticipated changes for the period 2060–2080 will already have occurred in 2040–2060. The predicted range expansion of European beewolf suggests that occurrence and abundance of this species should be monitored.

Spatio-temporal pattern of cross-continental invasion: Evidence of climatic niche shift and predicted range expansion provide management insights for smooth cordgrass

Introduction and spread of the halophyte Spartina alterniflora is one of the largest continental-scale biological invasion events in Asia and the Americas. Rapid globalization and broad environmental tolerance of the species increase the chance of novel invasions. Thus, we aimed to identify susceptible regions to inform prevention and control activities.A comprehensive global occurrence dataset and corresponding bioclimatic variables were used to characterize the species' climatic niche and predict current and future potential distributions. Conservatism of climatic niche between native and non-native ranges was tested, and climatic niche dynamics were analysed at spatial and temporal scales. The ensemble of eight species distribution models and eight climate change models was used to map the potential distribution of S. alterniflora under current and future climate conditions. We investigated the susceptibility of threatened ecosystems like mangroves and protected areas to S. alterniflora invasion to better inform management decisions.Our study revealed wide climatic tolerance and significant niche expansion of the species from humid regions of its native range to dry and arid environments of its non-native range with a very short lag period. With a marginal increase in temperature and precipitation in the future, range expansion was predicted towards higher latitude and more inland areas. The mangroves area, salt marshes, and protected areas that are at risk of ongoing and future invasions were identified. Given the invasion potential of S. alterniflora, the areas identified as climatically susceptible for the species’ establishment, both in current and future climates, should be prioritized for management actions.

Ocean Indicators Predict Range Expansion of an Introduced Species: Invasion History of the European Green Crab Carcinus maenas on the North American Pacific Coast

An introduced population of European green crabs Carcinus maenas (Linneaus, 1758) was established in San Francisco Bay prior to 1991. Their subsequent northern range expansion is linked to larval transport in the Davidson Current to northern California (1993), southern Oregon (approximately 1996), the Oregon and Washington coastal estuaries and the west coast of Vancouver Island, British Columbia (1998). Range expansions through larval transport to the central British Columbia coast occurred before 2010, to Haida Gwaii in 2020, and into the inland Salish Sea in 2015 and 2016. Both the range expansions of C. maenas and local abundance are strongly linked to oceanic factors during their larval development. These include (1) strong northward flow of coastal waters during winter; (2) warm surface water temperatures (>10°C for larval development); and (3) coastal circulation patterns that keep larvae close to shore, where they can be carried by wind and tidal currents into estuaries and embayments to settle. The strongest year classes and largest range expansions occurred during the last two major El Niño events. The 1997 to 1998 El Niño resulted in the colonization of embayments in Oregon, coastal Washington, and on the west coast of Vancouver Island, while the El Niño of 2015 to 2016 and the Pacific Warm Blob are linked to the range expansion into the Salish Sea. More local range expansions along the west coast of Vancouver Island, to the central British Columbia Coast, to Haida Gwaii, and inside the Salish Sea occurred during non-El Niño years.

Shifts from pulled to pushed range expansions caused by reduction of landscape connectivity

Range expansions are key processes shaping the distribution of species; their ecological and evolutionary dynamics have become especially relevant today, as human influence reshapes ecosystems worldwide. Many attempts to explain and predict range expansions assume, explicitly or implicitly, so‐called ‘pulled' expansion dynamics, in which the low‐density edge populations provide most of the ‘fuel' for the species advance. Some expansions, however, exhibit very different dynamics, with high‐density populations behind the front ‘pushing' the expansion forward. These two types of expansions are predicted to have different effects on e.g. genetic diversity and habitat quality sensitivity. However, empirical studies are lacking due to the challenge of generating reliably pushed versus pulled expansions in the laboratory, or discriminating them in the field. We here propose that manipulating the degree of connectivity among populations may prove a more generalizable way to create pushed expansions. We demonstrate this with individual‐based simulations as well as replicated experimental range expansions (using the parasitoid wasp Trichogramma brassicae as model). By analyzing expansion velocities and neutral genetic diversity, we showed that reducing connectivity led to pushed dynamics. Low connectivity alone, i.e. without density‐dependent dispersal, can only lead to ‘weakly pushed' expansions, where invasion speed conforms to pushed expectations, but the decline in genetic diversity does not. In empirical expansions however, low connectivity may in some cases also lead to adjustments to the dispersal‐density function, recreating ‘classical' pushed expansions. In the current context of habitat loss and fragmentation, we need to better account for this relationship between connectivity and expansion regimes to successfully predict the ecological and evolutionary consequences of range expansions.

Stress tolerance of two freshwater invaders exposed to Microcystis aeruginosa and microcystin-LR

Invasion of freshwaters by non-native animal species is a major threat to global aquatic systems. Asian clams (Corbicula fluminea) and quagga mussels (Dreissena rostriformis bugensis) are two highly invasive bivalves in North America that share life histories that facilitate invasion; however, they may experience different stress tolerances which can influence local population distribution. We compare the sensitivity of these two bivalves to the environmental stressors Microcystis aeruginosa and its associated toxin, microcystin. In laboratory assays, we exposed both species to M. aeruginosa and measured oxygen consumption and filtration rate. Sensitivity to microcystin was evaluated through two oxidative stress biomarkers, catalase, and lipid peroxidation. Quagga mussels exhibited elevated physiological responses, consuming more oxygen with cyanobacteria exposure, at an approximately doubled rate compared to Asian clams. Both species had increased filtration rates when fed M. aeruginosa with quagga mussels filtering at an overall higher rate. Oxidative stress was variable in both species. These results indicate that quagga mussels may be more sensitive to M. aeruginosa and microcystin than Asian clams, possibly due to physiological differences associated with invasion histories. The findings from these studies can be used to predict range expansion and lead to more effective control of nuisance populations.

Modelling species distributions and environmental suitability highlights risk of plant invasions in western United States

AbstractAimNon‐native invasive plants impact ecosystems globally, and the distributions of many species are expanding. The current and potential distributions of many invaders have not been characterized at the broad scales needed for effective management. We modelled the distributions of 15 non‐native invasive grass and forb species of concern in western North America to define their environmental niches and predict potential invasion risk.LocationArid and semi‐arid western United States.MethodsWe modelled species distribution using presence/absence data from > 148,000 vegetation survey plots to predict the probability of presence of each species based on associated climate, soil, topography and disturbance records. Boosted regression tree models were trained and tested within a buffer distance from presence observations of each species. Buffers were optimized by adding absence observations from increasingly large areas until prediction of presence was maximized, as defined by the area under the precision‐recall curve (AUPRC). We evaluated model AUPRC and other metrics by cross‐validation within training areas, then projected final models within focal EPA level III ecoregions.ResultsFocal species were present in 2.7% to 21% of plots within model training areas of 40 to 340 km radius. Models conservatively estimated potential species presence, with typically low false positive rates and moderate sensitivity. The most influential predictors of presence included minimum temperature (especially for grasses), climatic water deficit, precipitation seasonality and fire history. Cold desert ecoregions were impacted by the most species, with predicted range expansion into the prairie ecoregions and infilling for Warm Desert species.Main conclusionsInvasive forb and grass species are likely to expand their ranges and continued increases in temperature, aridity and area burned will increase invasion risk. Monitoring species presence and absence and mapping known and potential ranges with a focus on presence detection, as in our methodology, will aid in identifying new invasions and prioritizing prevention and control.

Multi-scale habitat selection and impacts of climate change on the distribution of four sympatric meso-carnivores using random forest algorithm

BackgroundThe habitat resources are structured across different spatial scales in the environment, and thus animals perceive and select habitat resources at different spatial scales. Failure to adopt the scale-dependent framework in species habitat relationships may lead to biased inferences. Multi-scale species distribution models (SDMs) can thus improve the predictive ability as compared to single-scale approaches. This study outlines the importance of multi-scale modeling in assessing the species habitat relationships and may provide a methodological framework using a robust algorithm to model and predict habitat suitability maps (HSMs) for similar multi-species and multi-scale studies.ResultsWe used a supervised machine learning algorithm, random forest (RF), to assess the habitat relationships of Asiatic wildcat (Felis lybica ornata), jungle cat (Felis chaus), Indian fox (Vulpes bengalensis), and golden-jackal (Canis aureus) at ten spatial scales (500–5000 m) in human-dominated landscapes. We calculated out-of-bag (OOB) error rates of each predictor variable across ten scales to select the most influential spatial scale variables. The scale optimization (OOB rates) indicated that model performance was associated with variables at multiple spatial scales. The species occurrence tended to be related strongest to predictor variables at broader scales (5000 m). Multivariate RF models indicated landscape composition to be strong predictors of the Asiatic wildcat, jungle cat, and Indian fox occurrences. At the same time, topographic and climatic variables were the most important predictors determining the golden jackal distribution. Our models predicted range expansion in all four species under future climatic scenarios.ConclusionsOur results highlight the importance of using multiscale distribution models when predicting the distribution and species habitat relationships. The wide adaptability of meso-carnivores allows them to persist in human-dominated regions and may even thrive in disturbed habitats. These meso-carnivores are among the few species that may benefit from climate change.

Predicting range expansion of invasive species: Pitfalls and best practices for obtaining biologically realistic projections

AbstractAimSpecies distribution models (SDMs) are widely used to forecast potential range expansion of invasive species. However, invasive species occurrence datasets often have spatial biases that may violate key SDM assumptions. In this study, we examined alternative methods of spatial bias correction and multiple methods for model evaluation for seven invasive plant species.LocationNorth America.TaxonCommon Tansy (Tanacetum vulgare), Wild Parsnip (Pastinaca sativa), Leafy Spurge (Euphorbia virgata), Common Teasel (Dipsacus fullonum), Brown Knapweed (Centaurea jacea), Black Swallowwort (Vincetoxicum nigrum) and Dalmatian Toadflax (Linaria dalmatica).MethodsWe employed bias‐correction measures for both occurrence sampling and background sampling inputs in a factorial design for Maxent resulting in six potential models for each species. We evaluated our models for complexity, model fit and using commonly employed evaluation metrics: AUC, partial AUC, the continuous Boyce index and sensitivity. We then developed a structured process for model selection.ResultsModels developed without occurrence or background bias correction often were overly complex and did not transfer well to expanding range fronts. Conversely, models that employed occurrence and/or background bias‐correction measures were less complex, had better AICc scores and had greater projection into incipient areas. These simpler models were also more likely to be selected when evaluated using a process that integrated multiple evaluation metrics. We found that invasion history (e.g. established versus incipient) was associated with the effectiveness of spatial bias correction techniques.Main ConclusionsWhile challenges exist in building climate‐based correlative species distribution models for invasive species, we found that methods relying on maximizing AUC performed poorly for invasive species. We advocate for the use of multiple and diverse metrics for model evaluation. Users of species distribution models need to incorporate explicit consideration of model discrimination, model fit and model complexity into their decision‐making processes if they are to build biologically realistic models.

Exploring larval phenology as predictor for range expansion in an invasive species

Predicting range expansion of invasive species is one of the key challenges in ecology. We modelled the phenological window for successful larval release and development (WLR) in order to predict poleward expansion of the invasive crab Hemigrapsus sanguineus along the Atlantic coast of North America and north Europe. WLR quantifies the number of opportunities (in days) when larval release leads to a successful completion of the larval phase; WLR depends on the effects of temperature on the duration of larval development and survival. Successful larval development is a necessary requirement for the establishment of self‐persistent local populations. WLR was computed from a mechanistic model, based on in situ temperature time series and a laboratory–calibrated curve predicting duration of larval development from temperature. As a validation step, we checked that model predictions of the time of larval settlement matched observations from the field for our local population (Helgoland, North Sea). We then applied our model to the North American shores because larvae from our European population showed, in the laboratory, similar responses to temperature to those of a North American population. WLR correctly predicted the northern distribution limit in North American shores, where the poleward expansion of H. sanguineus appear to have stalled (as of 2015). For north Europe, where H. sanguineus is a recent invader, WLR predicted ample room for poleward expansion towards NE England and S Norway. We also explored the importance of year‐to‐year variation in temperature for WLR and potential expansion: variations in WLR highlighted the role of heat waves as likely promoters of recruitment subsidising sink populations located at the distribution limits. Overall, phenological windows may be used as a part of a warning system enabling more targeted programs for monitoring.

Low salinity negatively affects metabolic rate, food consumption, digestion and growth in invasive lionfish Pterois spp.

The establishment of the piscivorous lionfishPteroisspp. in the Western Atlantic and wider Caribbean is a well-documented example of a successful marine invasion. Recently, lionfish have been shown to colonise a wide range of ecosystems and tolerate a wider range of salinities than previously thought. In the present study, lionfish were maintained in aquaria under differing salinity treatments (10, 20 and 37 psu) similar to those they might experience in an estuarine ecosystem. The effects of long-term hyposaline exposure on growth, metabolic rate, maximum food consumption and digestion were examined. Consistent with previous studies, lionfish were able to survive in hyposaline conditions for extended periods of time. However, lionfish in the most hyposaline treatment (10 psu) exhibited reduced growth under low food conditions, lower maximum metabolic rate, lower aerobic scope, lower maximum food consumption, took longer to digest a standardized meal size and occupied a greater percentage of their aerobic scope during digestion. Results suggest that (1) given the ability of lionfish to tolerate low salinity, updated range expansion models should incorporate salinity data to improve accuracy of predicted range expansion and (2) the invasion of lionfish into low salinity ecosystems, although a serious concern, will not likely lead to the same level of population increase observed for coral reef habitats due to the physiological costs associated with living in low salinities.

Contemporary climate change hinders hybrid performance of ecologically dominant marine invertebrates.

Human activities alter patterns of biodiversity, particularly through species extinctions and range shifts. Two of these activities are human mediated transfer of species and contemporary climate change, and both allow previously isolated genotypes to come into contact and hybridize, potentially altering speciation rates. Hybrids have been shown to survive environmental conditions not tolerated by either parent, suggesting that, under some circumstances, hybrids may be able to expand their ranges and perform well under rapidly changing conditions. However, studies assessing how hybridization influences contemporary range shifts are scarce. We performed crosses on Pyura herdmani and Pyura stolonifera (Chordata, Tunicata), two closely related marine invertebrate species that are ecologically dominant and can hybridize. These sister species live in sympatry along the coasts of southern Africa, but one has a disjunct distribution that includes northern hemisphere sites. We experimentally assessed the performance of hybrid and parental crosses using different temperature regimes, including temperatures predicted under future climate change scenarios. We found that hybrids showed lower performance than parental crosses at the experimental temperatures, suggesting that hybrids are unlikely to expand their ranges to new environments. In turn, we found that the more widespread species performed better at a wide array of temperatures, indicating that this parental species may cope better with future conditions. This study illustrates how offspring fitness may provide key insights to predict range expansions and how contemporary climate change may mediate both the ability of hybrids to expand their ranges and the occurrence of speciation as a result of hybridization.

Niche dynamics and potential distribution of Butomus umbellatus under current and future climate scenarios in North America

Predicting the potential distribution of invaders is informative for pre-emptive policy or management decisions and identifying suitable areas for establishment of new populations. Temporal projection of potential distributions is complicated by the magnitude and pace of changing climate, which could alter suitability under future conditions. The wetland invader, Butomus umbellatus is widespread in the northern US and southern Canada, but potential for invasion into new areas is unknown. We used environmental niche modeling to address our hypotheses for B. umbellatus: (1) a climatic niche shift has occurred between native and invasive ranges, (2) suitable areas in the invaded range have been colonized, and (3) climate suitability is likely to change in future climates. Environmental niche is highly conserved and stable (0.761) between ranges of B. umbellatus. Ensemble forecast revealed that nearly 60% of the invaded range is climatically suitable, including large areas in both the southern US and Alaska. Under future climates, there is a net decrease of suitable area, although two of three global circulation models predict range expansion of this species across gas emission scenarios. Given that the area is already invaded or at risk for future invasion, development of geographically adaptable long-term management strategies is prudent.

Predicting range expansion of invasive ctenophore Mnemiopsis leidyi A. agassiz 1865 under current environmental conditions and future climate change scenarios

Since the late 1990s, global warming has increased especially in Eurasia. With the temperature rising, the harmful invasive species such as « ecosystem engineer » Mnemiopsis leidyi spread into the seas of Eurasia and continues expanding around the world. Based on field data we defined the ranges of key environmental parameters (SST, SSS and Chl concentration) required for M. leidyi occurrence, reproduction and population growth in Eurasia. First, we evaluated the parameters separately and plotted global climatology of each of them for M. leidyi reproduction conditions. Next, we combined all parameters and determined the areas sufficient for M. leidyi occurrence, reproduction and sterile dispersal. Our results based on climatological data match well with field data on occurrence and reproduction and confirm the areas of its establishment in Eurasian seas. Since this climatological approach was successful, we extended it to the global scale. Results demonstrate the ability of M. leidyi establishment worldwide both at present and in future in the case of global warming prolongation. Model assessments predict accelerated SST rise in the Northern Hemisphere. As a result, waters previously too cold for M. leidyi reproduction could become favorable, which is especially true off the Arctic coasts of Eurasia. These areas in summer and autumn are expected to be much wider and extend closer to the North Pole. It is important to point out that all M. leidyi habitats including native, recipient and prospective ones are situated in shallow coastal areas and inland water bodies (semi-closed and closed seas, bays, lagoons, fjords). Equally important is that the local currents can provide only the relatively short distance of M. leidyi transport while shipping acts as the major vector.