The study examined Armadillidium nasatum , A. vulgare , Haplophthalmus danicus , Porcellio dilatatus , P. laevis , P. scaber and Porcellionides pruinosus , seven terrestrial isopods treated as exotic in Japan and associated originally with Europe or the Mediterranean region. The underlying Japanese database contained 17,412 specimens compiled from 159 publications, museum records and the first author’s personal collection. After duplicate locations were excluded, the seven species were represented by 1,516 Japanese sites, while the European and North American occurrence datasets supplied 4,135 and 1,953 locations, respectively.

Five species were first reported in Japan in 1927; A. nasatum and P. dilatatus were first reported in 1943. Researchers used Maxent version 3.4.1 to construct environmental niche models from 19 bioclimatic variables in WorldClim version 2.0, mapped at five-arc-minute resolution. The variables included measures of temperature and precipitation.

To reduce multicollinearity, highly correlated predictors were removed when the absolute value of their Pearson correlation coefficient was at least 0.75. Models used linear and quadratic features to describe relationships between occurrence probability and environmental conditions while limiting overfitting. Because the records came from non-random sources, the researchers generated a kernel-density estimate of sampling bias and selected 10,000 background points weighted by that surface, creating a target-group background intended to account for uneven collection effort.

Two modelling approaches were compared for each species. Regional models used occurrence records from Japan alone, whereas global models combined Japanese records with those from Europe and North America. Training area under the curve, or AUC, ranged from 0.681 to 0.910 for the global models and from 0.712 to 0.857 for the regional models.

AUC values above 0.9 indicate high discriminatory performance, values from 0.7 to 0.9 represent reasonable or moderate performance, and values from 0.5 to 0.7 indicate poor performance. Global models performed better for A. nasatum , A. vulgare and P. dilatatus . The researchers used the global approach to map potential Japanese distributions because records confined to an invaded country may understate the full environmental range occupied by a species in its native and other invaded regions.

Temperature-related variables supplied most of the strongest climatic signals in the global models. Annual mean temperature contributed more than 25 percent for three species: A. nasatum , H. danicus and P. scaber . Mean diurnal temperature range exceeded a 25 percent contribution for five species: A. vulgare , H. danicus , P. laevis , P. scaber and P. pruinosus .

Temperature seasonality was also a major predictor for P. dilatatus , contributing 37.6 percent. Among precipitation variables, seasonality contributed more than 25 percent for A. nasatum , P. dilatatus and P. laevis , while precipitation in the wettest month was especially important for A. nasatum , exceeding 65 percent contribution and permutation importance. The response curves revealed shared and species-specific temperature patterns.

Annual mean temperature responses differed among the remaining species: A. nasatum , H. danicus and P. scaber were associated with temperatures above 15°C, while P. pruinosus showed a hump-shaped response across a more moderate range of approximately 15–25°C. The study’s authors noted that the annual mean temperatures assigned probabilities above 0.5 covered roughly 10–25°C across most of Japan except mountainous areas, suggesting that annual mean temperature alone was not the principal national-scale constraint for these species. Global potential distributions generally included western Honshu, Shikoku and Kyushu, although their boundaries varied among species.

Suitable areas for A. vulgare , P. scaber and P. pruinosus extended farther inland than those for A. nasatum and H. danicus . The projected range for P. scaber also included coastal Hokkaido, while that of P. laevis was concentrated more heavily in southwestern Japan. For P. dilatatus , the global and regional models both identified most of Kyushu and Shikoku, but the regional model additionally projected suitable coastal areas of Honshu and southern Hokkaido.

The broader global projections for the other six species suggest that their Japanese occurrence records had not yet reached all areas classified as climatically suitable, not that those areas will inevitably be occupied. Invasion stages were inferred by plotting regional against global model probabilities and dividing the results at a probability of 0.5. Areas classified as highly suitable by both models represented stabilising populations.

High global probability combined with low regional probability indicated colonising populations, whereas low probability in both models identified sink populations. A high regional probability paired with low global probability was interpreted as a locally adapted population. A. vulgare , H. danicus , P. laevis , P. scaber and P. pruinosus contained mixtures of stabilising and colonising areas, with several sink areas also identified.

A. nasatum was composed mainly of stabilising areas and one sink, while P. dilatatus produced the pattern assigned to local adaptation. These labels describe relationships between model predictions rather than observed demographic outcomes. For example, a colonising classification means that an area is climatically suitable in the global model but poorly represented by the species’ Japanese regional occurrence pattern; it does not establish a population trajectory or guarantee establishment.

Likewise, a sink classification is consistent with the presence of a species in an area predicted to be unsuitable, including cooler inland and northern locations, but it does not demonstrate that a population is declining. The four categories did not form sharply separated geographic regions. The authors also warned that occurrence records could not cover every part of the species’ ranges and that the projected maps might change as a larger, more complete database became available.

A. vulgare had the widest recorded Japanese range, extending from 43°10′ north to 24°45′ north, and occurred at 770 sites. P. scaber was recorded at 393 sites and was the only species commonly reported in Hokkaido. The Japanese records for A. nasatum , P. dilatatus and P. laevis numbered 20, seven and 32 sites, respectively, while P. pruinosus occurred at 174 sites and reached Iriomotejima Island at 24°16′ north, the southernmost location in the dataset.

The authors considered the short time since the first Japanese reports of A. nasatum , together with its large projected suitable area and introduction to suitable areas, one possible reason for its limited number of records. They also suggested that the ecological niche and areas of introduction were more relevant than elapsed time to the narrow Japanese range of P. dilatatus . The results show why occurrence records from an invaded region alone may underestimate the potential range of these seven exotic isopods.

Combining Japanese, European and North American data produced wider projections for six species and exposed areas where further establishment may be possible. The analysis did not establish ecological harm, human exposure or the consequences of future expansion, and its macro-scale climate models did not include every local influence on isopods. Within those limits, the study identifies temperature and diurnal temperature variation as major climatic correlates and suggests that six of the seven modelled species retained geographic scope for potential expansion beyond their documented Japanese ranges.

Subject of Research: Ecological niche modelling of seven exotic terrestrial isopod distributions and invasion stages in Japan

Article Title: Invasion stages and potential distributions of seven exotic terrestrial isopods in Japan

Article References: Karasawa, S., & Nakata, K. (2018). Invasion stages and potential distributions of seven exotic terrestrial isopods in Japan. BioRisk, 13, 53-76. https://doi.org/10.3897/biorisk.13.23514

Image Credits: AI Generated

DOI: 10.3897/biorisk.13.23514

Keywords: terrestrial isopods, Japan, ecological niche modelling, species distribution models, invasive species, climatic niche, temperature variables, Maxent, invasion stages, soil biodiversity, Invasion, stages

The Trans-Mexican Volcanic Belt, the geographic stage for this assessment, is a geological newcomer by evolutionary standards yet an ancient cradle of biodiversity. Formed by the subduction of the Cocos and Rivera plates beneath the North American Plate, this Neogene volcanic arc stretches roughly 160,000 square kilometres across central Mexico, from west to east, in a chain of stratovolcanoes, volcanic fields and highlands that in places rise above 4,000 metres. Repeated volcanic episodes, tectonic uplift and the climatic oscillations of the Pleistocene carved the region into a mosaic of temperate forests, alpine grasslands and xerophytic scrublands. That mosaic, in turn, generated the environmental gradients and geographic isolation that drive speciation. The result is a region that ranks second in herpetological richness nationwide and holds the highest number of endemic reptiles and amphibians in the country, with approximately a quarter of Mexico’s herpetofauna found there and more than 80 percent of those species endemic. For spiny lizards of the genus Sceloporus, many of which are montane specialists tied to particular elevational bands and rock outcrops, these gradients have acted both as engines of diversification and, increasingly, as traps: species adapted to narrow climatic conditions on isolated mountain blocks have limited capacity to shift their ranges when those blocks become surrounded by cities, fields and pastures.

The methodology behind the new study reflects a broader shift in conservation science away from single-metric assessments and toward integrative, spatially explicit frameworks. The researchers compiled occurrence records for the 17 species from a suite of biodiversity databases, including REMIB, UNIBIO, GBIF, HERPNET, VertNet and IREKANI, supplemented by community-sourced observations from iNaturalist, restricting records to recent decades to ensure the data reflected current distributions rather than historical ones. Occurrence data of this kind are the raw material of ecological niche modelling, a technique that relates known locations to environmental variables such as temperature, precipitation and vegetation cover to estimate the full envelope of suitable habitat. The team employed two complementary modelling strategies: Maxent, a widely used maximum-entropy approach tuned through the ENMeval package to avoid overfitting, and an ensemble method implemented in biomod2 that combines eight different algorithms. Ensemble approaches are increasingly favoured because individual algorithms can disagree, and averaging their predictions, optimised against known occurrences, tends to yield more robust estimates of where a species can persist. From the resulting binary distribution maps, the researchers calculated landscape metrics for each species: total habitat area, the number of discrete habitat patches and the mean size of those patches.

These fragmentation metrics matter because the fate of a population depends not only on how much habitat exists but on how it is arranged. Conservation biology has long recognised that a given area of habitat divided into many small, isolated patches supports fewer individuals and fewer species than the same area in a single contiguous block. Small patches suffer from edge effects, where conditions at the boundary of a fragment differ from the interior, and from demographic and genetic consequences of isolation. Lizards are particularly sensitive to these dynamics because their dispersal ability is limited; a Sceloporus population stranded on a volcanic slope surrounded by agricultural land is unlikely to recolonise neighbouring patches after a local extinction event. The study synthesised habitat area, patch count and patch size into a composite vulnerability index, allowing species to be ranked not merely by how much habitat they retain but by how broken up that habitat has become.

To capture the human dimension of the threat, the researchers overlaid species distributions with land-use layers representing urban development, agriculture and cultivated pasture. They then applied principal component analysis and k-means clustering to these pressure variables, producing a multivariate anthropogenic pressure zonation across the region. This statistical approach condenses multiple correlated pressure layers into a coherent spatial classification, distinguishing zones where pressures are predominantly urban from those dominated by agricultural conversion or mixed land use. The bivariate risk assessment that followed, crossing vulnerability with pressure, produced the study’s most consequential finding: Sceloporus megalepidurus emerged as the only species facing both high pressure and high vulnerability simultaneously, a combination that places it in the most precarious category of the analysis.

The protected-area component of the study addresses a persistent gap in conservation planning: representation. A protected area only benefits a species if it overlaps that species’ actual habitat. Mexico has invested substantially in its system of federal and state protected natural areas, but these were often established for scenic, hydrological or flagship-species values rather than for the fine-grained distribution of reptiles. The comparison of species distributions against protected-area coverage revealed how poorly the existing network captures the habitats of these lizards, leaving large portions of biologically rich landscape exposed to ongoing transformation. This mismatch is compounded by management shortcomings; even formally protected areas in the region are frequently under-resourced and subject to encroachment.

Perhaps the most sobering implication of the work concerns the IUCN Red List categories of the species involved. Most of the 17 lizards are currently classified as Least Concern or have never been evaluated at all. Only Sceloporus megalepidurus carries a Vulnerable listing internationally, and under Mexican national normative standards only S. grammicus and S. megalepidurus receive any formal protection status. Yet the spatial analysis flagged alarming risk signals in species such as S. anahuacus, S. albiventris and S. minor, all of which sit in the least-concern or unevaluated categories. This discrepancy illustrates a structural limitation of global assessments: they typically rely on geographic range size as a primary criterion, and a species with a moderately large mapped range can appear secure even when that range is riddled with cities, fragmented into small patches and largely unprotected. Red List criteria do include provisions for declining habitat quality and fragmented distributions, but these are difficult to apply without the kind of fine-scale spatial data that regional studies like this one generate. The authors argue, in effect, that conservation assessments should incorporate habitat quality, fragmentation and exposure to land-use pressures rather than relying on range extent alone.

The findings also resonate with a broader and troubling literature on lizard responses to environmental change. Research published under the leadership of Barry Sinervo and colleagues demonstrated that climate change has already driven measurable local extinctions in lizard populations worldwide, with roughly 12 percent of Mexican populations disappearing since 1975. Their physiologically grounded models, validated against field surveys across multiple continents, projected that by 2080 local extinctions could approach 39 percent globally, with up to 20 percent of lizard species lost. The mechanism is deceptively simple: lizards are ectotherms whose activity windows are constrained by temperature, and as warming shrinks the hours available for foraging and reproduction, populations decline even without any direct habitat destruction. When this thermal stress is layered on top of habitat loss, fragmentation and reduced connectivity, the risks compound rather than merely add. A population squeezed by urbanisation into a small remnant patch has neither the geographic room to track shifting climates nor the demographic resilience to absorb climate-driven reproductive failures.

The genus Sceloporus itself amplifies the significance of these results. With approximately 110 recognised species, 106 of them endemic to Mexico, spiny lizards represent one of the most successful radiations in the Mexican herpetofauna, occupying habitats from montane forests to arid scrublands and grasslands. Their ecological roles as insect predators and prey for birds, snakes and mammals weave them into food webs across the country. Yet despite decades of research on their thermal physiology, systematics and biogeographic history, fundamental questions about the environmental drivers of their distributions and their vulnerability to human pressures have remained unanswered. Few prior studies had combined ecological niche modelling with multivariate pressure mapping, fragmentation analysis and protected-area overlap in a single framework, which is precisely the integration this study delivers.

For conservation practitioners, the practical value of the approach lies in its ability to prioritise. By ranking species on a composite vulnerability index and mapping where high vulnerability coincides with high anthropogenic pressure, the framework identifies both the species most in need of attention and the specific landscapes where intervention would be most effective. It also provides an evidence base for revisiting national listings under Mexican environmental law, where the current coverage of Sceloporus species is sparse relative to the risks documented here. More broadly, the study offers a template that could be applied to other poorly assessed, range-restricted taxa in biodiversity hotspots worldwide, wherever the gap between formal conservation status and actual spatial risk remains wide. In a region where human population density and endemism both peak, that gap is not an academic concern but a measure of how much biodiversity may be lost before it is ever formally recognised as threatened.

Subject of Research: Spatial vulnerability assessment of 17 Sceloporus lizard species in the Trans-Mexican Volcanic Belt under anthropogenic pressure

Article Title: Assessment of the vulnerability of Spiny Lizards in Central Mexico under anthropogenic pressure: integrating habitat suitability, landscape connectivity, fragmentation and protected area coverage

Article References: Vargas-Jaimes, J., Manjarrez, J., Ramírez-Corona, F., Woolrich-Piña, G. A., González-Pedroza, M. G., Estrada-Zúñiga, M. E., Rangel-Patiño, C. A., Venegas-Barrera, C. S., Nieto-Trujillo, A., Vazquez-Marquez, A. M., Guido-Patiño, J. C., & Sunny, A. (2025). Assessment of the vulnerability of Spiny Lizards in Central Mexico under anthropogenic pressure: integrating habitat suitability, landscape connectivity, fragmentation and protected area coverage. Nature Conservation, 59, 351-386. https://doi.org/10.3897/natureconservation.59.159660

Image Credits: AI Generated

DOI: 10.3897/natureconservation.59.159660

Keywords: Sceloporus, Trans-Mexican Volcanic Belt, ecological niche modelling, habitat fragmentation, landscape connectivity, protected areas, anthropogenic pressure, conservation, reptiles, Mexico biodiversity, IUCN Red List, deforestation

The African sharptooth catfish is one of the world’s most widely introduced freshwater fish, exported globally for aquaculture because of its rapid growth, disease resistance, tolerance of crowded ponds, and ability to breathe atmospheric oxygen and even disperse overland. Adults commonly exceed one metre in length. Those same traits, however, make it a formidable invader, and the species has been linked elsewhere to the displacement of native fish, food web disruption, and parasite transmission. In Türkiye, it has gained a foothold in a section of the Sakarya River warmed by springs, where it now coexists with the Wels catfish, a species that is native and declining in the region even though it behaves as a damaging invader in other parts of Europe.

To measure predation pressure directly, the team ran comparative functional response experiments, a standard tool in invasion science that quantifies how efficiently a predator consumes prey as prey density rises. Wild-caught catfish of both species were offered two prey fish at densities from one to 64 individuals in 90-litre tanks held at 21.5 degrees Celsius, matching the average temperature of the collection sites. One prey was the native bleak Alburnus escherichii, the dominant small fish at the study site; the other was gibel carp, Carassius gibelio, an invasive cyprinid now widespread across the country. The number of prey eaten after 24 hours was used to estimate each predator’s attack rate and handling time.

Every predator-prey combination produced a Type II functional response, the classic pattern in which consumption is disproportionately high when prey are scarce, a dynamic that can drive prey populations toward local collapse. The critical difference emerged between prey species. Both catfish took significantly longer to handle gibel carp than bleak, and the functional response ratio, which integrates attack rate and handling time into a single measure of predatory impact, was roughly three times higher on the native prey. Clarias gariepinus posted a ratio of 203.5 on the bleak compared with 61.3 on gibel carp; for Silurus glanis the corresponding figures were 123.5 and 49.0. Clarias gariepinus also attacked the native bleak at a significantly higher rate than the Wels catfish did.

The researchers attribute the gibel carp’s partial refuge from predation to its deeper body shape and to the predators’ lack of evolutionary experience with it, whereas slender-bodied bleak closely resemble South African minnows and barbs whose populations have crashed following sharptooth catfish invasions. Because both predators converge on the same native prey, their combined presence could destabilize bleak populations faster than either predator acting alone, a concern sharpened by the fact that the invaders consumed more of the native prey per unit time under the study’s warm conditions.

Laboratory results, however, can oversimplify natural food webs, so the team also analysed stable isotopes of carbon and nitrogen in muscle tissue from fifteen wild specimens of each species. Nitrogen isotope ratios placed both predators at similar trophic positions, with the Wels catfish slightly higher at 3.57 versus 3.30 for the African catfish. Yet their isotopic niches barely overlapped: the African catfish’s niche ellipse overlapped only 5.4 percent of the Wels catfish’s at the 95 percent level, and a negligible 0.3 percent at the core 40 percent level. The narrower isotope signature of the African catfish suggests it feeds on a more specialized subset of resources in the wild, consistent with the idea that generalist invaders can shrink their trophic niche when sharing waters with a native competitor, easing direct conflict while maintaining pressure on shared prey.

The third strand of the study looked outward in space and forward in time. Using nine modelling algorithms and quality-controlled occurrence records filtered for spatial errors and autocorrelation, the researchers built ensemble ecological niche models for both predators and both prey, then projected habitat suitability under two CMIP6 climate scenarios, an intermediate SSP1-2.6 pathway and a high-emission SSP5-8.5 pathway, for mid-century and end-of-century horizons. Model performance was strong, with True Skill Statistics above 0.6 for all species and reaching 0.93 or higher for the Wels catfish and gibel carp in the best algorithms.

The projections tell a coherent story about climate niches. The African catfish is associated with thermally stable environments with moderate seasonal variability, while the Wels catfish prefers regions with pronounced seasonal temperature swings and is sensitive to cold-quarter temperatures. The native bleak is likewise governed by temperature-related variables and favours areas with distinct seasons but low daily fluctuation. Under future scenarios, both predators are projected to expand their ranges, and their overlapping habitat increases, raising the probability of interspecific encounters and competition. The Wels catfish’s climatic tolerance aligns more closely with bleak habitat across temperate Europe, meaning the native predator may threaten the native prey over a broader area than the invader, at least climatically.

The authors are careful to frame the models as risk maps rather than prophecies. Species distribution models identify where interactions could plausibly occur, but they cannot predict the outcome of competition or predation because they omit behavioural flexibility, diet switching, and density-dependent processes. Fully forecasting predator dynamics under climate change, they note, would require individual-based or mechanistic multispecies models parameterized with interaction data that do not yet exist. The study also acknowledges limits in its field evidence: isotope samples came only from the sympatric site, so niche separation could not be confirmed where the species occur apart, and factors such as dissolved oxygen, flow, habitat structure, and pollution were outside the modelling scope.

The conservation implications extend well beyond one Turkish river. Hot-spring refugia like Eminekin act as invasion beachheads, and connectivity during warm months is expected to strengthen as the climate warms, allowing thermally tolerant invaders to disperse outward. Meanwhile the Wels catfish, historically a keystone structure in these fish communities, is being squeezed by overfishing, pollution, drought, and now competition from a functionally similar invader prized by some anglers, whose translocations and stocking practices may further shape future distributions. The researchers argue for habitat restoration, vigilant monitoring of predator-prey dynamics, stricter regulation of aquaculture and stocking, and climate-adaptive biosecurity planning, coupled with transboundary cooperation across Eurasia. As their integrated evidence shows, warming waters do not merely shift species ranges on a map; they can raise the per-capita predatory power of an invasive fish, redraw the boundaries of its conflict with native predators, and leave vulnerable native prey caught between both.

Subject of Research: Trophic interactions and climate-driven range dynamics of invasive and native catfish in Turkish freshwater ecosystems

Article Title: Trophic interactions and climate-driven range dynamics of native and invasive catfish in freshwater ecosystems

Article References: Başkurt, S., Emiroğlu, Ö., Aksu, S., Köse, E., Mol, O., Çınar, E., South, J., & Tarkan, A. S. (2026). Trophic interactions and climate-driven range dynamics of native and invasive catfish in freshwater ecosystems. NeoBiota, 105, 67-88. https://doi.org/10.3897/neobiota.105.174895

Image Credits: AI Generated

DOI: 10.3897/neobiota.105.174895

Keywords: invasive species, Clarias gariepinus, Silurus glanis, functional response, stable isotope analysis, ecological niche modelling, climate change, freshwater ecosystems, predation, Sakarya River, biodiversity conservation, species distribution models

Amphibians are among the most threatened vertebrate groups worldwide, with population declines driven by climate change, habitat degradation and the spread of emerging infectious diseases. Bd, the causative agent of chytridiomycosis, was first described in 1999 as the agent behind massive amphibian die-offs, but its presence in Mexico dates back to the 1970s. The pathogen is now widespread, particularly in the central and southern regions of the country, and has been reported to infect at least 50 amphibian species in Mexico. Hylidae and Plethodontidae are among the most affected families, with the genera Hyla, Ambystoma and Pseudoeurycea ranking as the most impacted, their species concentrated across central and southern Mexico.

Mexico is a global hotspot of amphibian diversity and endemism, hosting approximately 3.69 percent of the world’s anuran species. The country’s most diverse amphibian family, Plethodontidae, comprises 140 species that primarily inhabit high-elevation forests in the Trans-Mexican Volcanic Belt, the Sierra Madre Oriental and the montane regions of the Sierra Madre del Sur, the Balsas Depression and Oaxaca. Hylidae is the second most diverse family with approximately 101 species, while Ambystomatidae, though lower in species richness with 12 to 18 species depending on the taxonomic framework, includes 16 endemic species, making Mexico the centre of diversity for the group.

The research team selected 13 amphibian species based on endemism, conservation status and ecological relevance within the montane regions of central Mexico. The selection included three Hyla species (H. euphorbiacea, H. eximia and H. plicata), three Ambystoma species (A. altamirani, A. lermaense and A. velasci) and seven Pseudoeurycea species (P. altamontana, P. gadovii, P. juarezi, P. lineola, P. longicauda, P. smithi and P. werleri). All are endemic to Mexico, and most inhabit high-elevation cloud forests or temperate montane ecosystems that are particularly susceptible to climate change, habitat loss and emerging diseases. The species span a broad spectrum of IUCN Red List categories: four are listed as Least Concern, one as Vulnerable, seven as Endangered and one, P. smithi, as Critically Endangered.

Notably, most Pseudoeurycea species included in the study are extremely data deficient. For several of them, only presence records are available, with almost no information on their population sizes, ecology, reproductive behaviour or physiological tolerances. This scarcity of data results in their exclusion from many broad-scale conservation initiatives, despite the likelihood that they are among the most vulnerable to environmental disturbance and chronic infections. By including this taxonomically and ecologically diverse group, ranging from broadly distributed species to microendemics with only a handful of records, the study aimed to provide a more integrative evaluation of the potential impacts of Bd across a gradient of conservation statuses and research gaps.

Methodologically, the researchers compiled occurrence records from online databases including GBIF, iNaturalist and CONABIO, while Bd records were obtained from a previous study and its associated Dryad data repository, covering the period from 2000 to 2022. Records were filtered to remove coordinate errors, duplicates and points outside known geographic ranges, then spatially rarefied to retain only one occurrence per square kilometre, an approach shown to reduce model overfitting. Nineteen bioclimatic variables at roughly one kilometre resolution were obtained from WorldClim, along with elevation and land-cover variables derived from satellite imagery. A Pearson correlation analysis eliminated highly correlated variables, retaining seven final land-cover layers: percentage cover of agriculture, arid vegetation, grassland, fir forest, pine forest, oak forest and cloud forest.

Two distinct modelling methodologies were employed to facilitate comparative analysis. The first used the maximum entropy algorithm implemented through the ENMeval package in R, testing regularisation multipliers and feature class combinations, with 100,000 background points randomly generated to characterise the environmental background. A block method partitioned occurrence data geographically based on latitude and longitude, ensuring that training and evaluation datasets were separated across space. The second approach constructed an ensemble model with the biomod2 package, combining ten algorithms including generalised linear models, random forest, Maxent and XGBOOST, each run ten times with different selections of training and testing datasets. Model performance was assessed using the area under the curve of receiver operating characteristic plots, partial ROC analyses and the true skill statistic.

The results showed that the maximum temperature in the warmest month, the minimum temperature in the coldest month and precipitation in the wettest and driest months were the most important environmental variables for the amphibian species. For most Ambystoma species, the optimal habitat suitability fell between roughly minus two and ten degrees Celsius for the coldest month, while A. lermaense presented an optimum temperature range of 15 to 25 degrees. For Bd, the maximum temperature in the warmest month was positive within a range of approximately 15 to 35 degrees, and the minimum temperature of the coldest month was a negative variable. The optimal temperature range for Bd was found to lie between 10 and 25 degrees, aligning with observations from European studies. Elevation was a positive variable for all species, and pine, oak and cloud forest percentages were positive for nearly all species.

According to the tenth percentile training presence threshold, Bd had the greatest potential distribution among all species studied, covering 267,557 square kilometres, while the most restricted species, P. altamontana, covered just 9,982 square kilometres. Niche overlap analysis revealed that Bd and A. altamirani showed relatively higher overlap values (Schoener’s D = 0.423; Hellinger’s I = 0.572), suggesting a greater degree of environmental similarity compared to other species pairs. In contrast, A. lermaense exhibited the lowest overlap with Bd (D = 0.038; I = 0.178). Barplot analysis indicated that P. juarezi, P. longicauda and P. altamontana exhibited the highest percentage of spatial overlap with Bd, all exceeding 70 percent of their distribution ranges, while A. velasci and H. eximia had the lowest overlap, below 40 percent.

By integrating spatial exposure information with IUCN Red List categories, the researchers developed a composite vulnerability index that ranked P. altamontana, P. longicauda and P. juarezi as the most vulnerable species. A principal component analysis of vulnerability patterns revealed distinct species clusters, with the first two components accounting for 92.3 and 7.7 percent of the variance respectively. Species richness maps showed that amphibian diversity peaks in the central highlands of Mexico, particularly in regions overlapping with the Trans-Mexican Volcanic Belt, where richness values reach up to nine species per pixel, and the overlay analysis demonstrated that Bd suitability was notably high in these same regions. The authors emphasise the urgency of implementing targeted conservation actions, including long-term monitoring, early detection of infections, identification of resistant or tolerant populations and regulation of ecotourism in vulnerable regions. They also highlight the potential importance of range break zones, such as Oaxaca and the Altiplano Sur, as natural barriers that could limit Bd spread, and note that community-based conservation initiatives and voluntary reserves managed by indigenous people offer an opportunity to expand protected areas and implement habitat restoration programmes.

Subject of Research: Ecological niche overlap between the chytrid fungus Batrachochytrium dendrobatidis and endemic amphibians in Mexico's Central-Southern Highlands

Article Title: Mapping Risk Zones: niche overlap between Batrachochytrium dendrobatidis and endemic amphibians in Mexico’s Central-Southern Highlands

Article References: Heredia-Bobadilla, R. L., Manjarrez, J., Gómez-Benítez, A., Reyes-Velázquez, E. A., Carmen-Cristobal, J. M., Sánchez-Lara, A. J., Martínez-Alva, G., Bolom-Huet, R., & Sunny, A. (2026). Mapping Risk Zones: niche overlap between Batrachochytrium dendrobatidis and endemic amphibians in Mexico’s Central-Southern Highlands. Nature Conservation, 63, 299-335. https://doi.org/10.3897/natureconservation.63.163964

Image Credits: AI Generated

DOI: 10.3897/natureconservation.63.163964

Keywords: Batrachochytrium dendrobatidis, chytridiomycosis, amphibian conservation, ecological niche modelling, Mexico, Trans-Mexican Volcanic Belt, Sierra Madre del Sur, Pseudoeurycea, Ambystoma, Hyla, niche overlap, biodiversity hotspots

The research, led by Finnbar Lee of the Cawthron Institute in Nelson, New Zealand, together with Ian Kusabs, George Perry, and Calum MacNeil, introduces what the team calls the refugia habitat metric, or RHM. The idea is elegantly simple. Standard ecological niche models predict where conditions are suitable for a species based on environmental variables such as temperature, rainfall, and habitat structure. The RHM takes those native-species suitability scores and then down-weights them wherever an invasive species is also predicted to thrive. The result is a map that highlights habitat which is simultaneously good for the native species and bad for the invader — precisely the kind of ground where a vulnerable population has the best chance of holding on through the coming decades.

Mathematically, the metric works by calculating a weighting parameter from the habitat suitability scores of all invasive species considered, each scaled by a coefficient reflecting the strength of its interaction with the native species. The native suitability score is then reduced by a negative exponential function of that combined invasion pressure. The exponential form reflects a deliberate ecological assumption: as invasion pressure mounts, each additional increment of invader suitability has a diminishing further effect, because the harm to the native species eventually saturates. The metric is deliberately flexible. It can incorporate any number of invasive species, works with any niche-modelling algorithm that produces suitability scores between zero and one, and includes tunable parameters that let experts adjust how strongly a particular invader penalizes the native score. When the invader is absent or harmless, the metric simply collapses back to the ordinary habitat suitability value.

To demonstrate the tool, the researchers turned to a case study with deep cultural resonance. The northern kōura (Paranephrops planifrons) is a freshwater crayfish endemic to Aotearoa New Zealand, treasured as a taonga species by Māori and central to customary food-gathering practices known as mahinga kai. Kōura prefer cool, slow-moving water with woody debris and coarse substrates, and their biology is tightly governed by temperature: their optimum mean daily temperature is around 19 degrees Celsius, with a critical upper limit near 32 degrees. The species is already classified as At Risk: Declining, and it faces a formidable adversary in the brown bullhead catfish (Ameiurus nebulosus), a North American invader deliberately introduced to New Zealand in 1877 for sport fishing.

The bullhead catfish is a textbook climate-change winner. It tolerates water temperatures up to 37.5 degrees, spawns across a wide thermal range of 14 to 29 degrees, survives low oxygen and poor water quality, and eats almost anything. Until 1985 it was confined to the lower Waikato River, but it has since spread through the river system, reached Lake Taupō, and by 2016 and 2018 had arrived in the Rotorua lakes. Its impact on kōura can be severe: a study of catfish stomach contents from the rocky shorelines of Lake Taupō found that 64 percent of large catfish contained kōura, marking the catfish as a major predator. Where catfish establish, kōura decline.

Lee and colleagues built maximum entropy (MaxEnt) niche models for both species using thousands of cleaned occurrence records from the New Zealand Freshwater Fish Database, combined with river-reach variables from the Freshwater Environments of New Zealand database and climate variables from national projection datasets. The models were carefully tuned, cross-validated, and assessed with multiple performance statistics; the catfish model achieved an area under the curve of 0.92, while the kōura model reached 0.81. The team also quantified how far their projections extrapolated beyond the training data using a novel shape metric, flagging where predictions were least certain. Future projections used the mean of six global climate models downscaled to New Zealand under the SSP3-7.0 emissions scenario for the period 2080 to 2100.

The projections tell a story of converging pressures. By the end of the century, suitable habitat for bullhead catfish is predicted to remain stable or expand, with significant increases across the northern and western North Island. Kōura habitat, by contrast, is expected to decline across much of its current North Island range and shift southwards and towards more mountainous terrain, while parts of the South Island outside the current range become more suitable. In total, the amount of the country favorable to kōura may remain relatively stable, but its location will move — and the catfish will be following the warmth into exactly the kind of slow, lowland waters the crayfish favors.

Applying the RHM to these suitability surfaces produced maps of potential refugia with immediate management value. Under current conditions, high-priority refugia exist within the kōura’s present range, particularly in the western and southern North Island and across the north and west of the South Island, with additional significant refugia beyond the current range in the eastern South Island. Under the future scenario, refugia contract in the northern North Island but persist in the western North Island and the South Island. Because kōura have limited dispersal ability — one distributional gap in the eastern North Island is thought to date from local extirpation by volcanic eruptions — the authors argue that natural range shifts are unlikely without help. Translocation, a practice with a long history in kōura fisheries management, could bridge that gap, and the RHM offers a principled way to choose destination sites.

The authors are candid about the metric’s limits. It assumes that high invader suitability implies high ecological risk, a relationship that varies with context: catfish predation on kōura, for example, is moderated where native eels are abundant and dominate the catfish, and the same Lake Taupō study found kōura in only 15 percent of large catfish from weedy shorelines compared with 64 percent from rocky ones, showing how habitat structure shapes interaction strength. The metric also inherits the limitations of its underlying niche models, ignores dispersal barriers and fine-scale microrefugia such as spring-fed headwater streams, and treats invasion pressure as static rather than dynamic. The researchers recommend using the RHM alongside mechanistic models, physiological data, and connectivity analyses rather than in isolation, and they call for empirical validation against long-term monitoring data and invasion chronosequences.

Even with those caveats, the tool arrives at a pressing moment. The 2023 invasion of New Zealand’s freshwaters by the gold or Asian clam (Corbicula fluminea), an ecosystem engineer capable of displacing culturally valued native bivalves, has pushed conservation translocations — moving native species out of the path of spreading invaders — into active policy debate. The RHM’s flexibility means it can be applied to terrestrial, freshwater, and marine systems, to plants as readily as to animals, and at scales from single reserves to continental assessments. For conservation managers forced to allocate scarce resources, the promise is concrete: instead of choosing between climate protection and invasion defense, they can now identify the places where a single investment serves both, giving vulnerable natives their best remaining ground on which to make a stand.

Subject of Research: A refugia habitat metric integrating ecological niche models of native and invasive species to identify climate refugia, demonstrated on New Zealand's kōura crayfish and invasive brown bullhead catfish

Article Title: Identifying refugia from the synergistic threats of climate change and invasive species

Article References: Lee, F., Kusabs, I. A. K., Perry, G. L. W., & MacNeil, C. (2025). Identifying refugia from the synergistic threats of climate change and invasive species. Web Ecology, 25(2), 221-239. https://doi.org/10.5194/we-25-221-2025

Image Credits: AI Generated

DOI: 10.5194/we-25-221-2025

Keywords: climate change, invasive species, refugia, ecological niche modelling, MaxEnt, kōura, freshwater crayfish, brown bullhead catfish, New Zealand, conservation, biodiversity, translocation

The study, published in the journal Ecology and Evolution, focused on a roughly 30 square kilometre area on the western flank of the Nimba range, home to two chimpanzee communities totalling around 89 individuals. Although local customs and national law strictly prohibit chimpanzee hunting — a taboo documented in the region since the 1970s — hunters from outside the area do not necessarily share those prohibitions. Even when chimpanzees are not the target, poaching for smaller mammals generates by-catch, injuries and pervasive human disturbance that can reshape how these intelligent apes use their forest home. Previous research has shown that where hunting occurs, chimpanzees tend to spatially avoid human presence, making fine-scale disturbance a genuine conservation concern even without direct killing.

Between August 2022 and August 2023, teams of Guinean researchers combed the mountainous terrain twenty days per month, logging 901 GPS occurrence points: 633 records of chimpanzee feeding and travelling, 185 nesting records, and 83 points of hunting evidence ranging from empty bullet casings and snare traps to hunting camps and campfires. The researchers deliberately separated nesting from feeding and travelling, reasoning that the two activities — one vulnerable and stationary, the other mobile — might respond differently to human pressure. After thinning the data to one record per 30-metre pixel, they generated pseudo-absence points only along surveyed tracks, a careful design choice that prevented the models from mistaking unsurveyed areas for genuinely unused habitat.

The methodological heart of the study lies in its multi-scale approach. Recognising that species respond to their environment at different spatial grains, the team transformed sixteen environmental variables — including elevation, slope, topographic position, vegetation indices, wetness and distances to villages, roads, rivers and research camps — into seven spatial scales ranging from 30 metres to 2 kilometres using Gaussian kernel smoothing in Google Earth Engine. For each activity type, univariate models identified the optimal scale for every predictor, a step that fewer than 5 percent of habitat modelling studies typically perform. The team then compared two complementary modelling frameworks: generalised linear models, prized for their statistical interpretability, and boosted regression trees, a machine learning method capable of capturing non-linear relationships and threshold effects that simpler models miss.

The results paint a nuanced picture of two species — human and chimpanzee — navigating the same landscape with partly overlapping, partly divergent logic. For hunters, distance to research camps emerged as the single most consistent predictor, with hunting probability rising sharply away from the camps. In the boosted regression tree models, tree cover was the most influential variable at the optimised 500-metre scale, with hunting activity dropping markedly where canopy cover exceeded 90 percent — dense forest apparently presenting obstacles and limited visibility that deter hunters pursuing smaller prey. Wetness at 1,500 metres and proximity to rivers also shaped hunting patterns, suggesting that difficult, waterlogged terrain offers chimpanzees a measure of natural protection.

Chimpanzees, for their part, revealed their own sophisticated habitat calculus. Feeding and travelling activity peaked above 750 metres in elevation, with the animals favouring steeper slopes, warmer south-facing aspects and areas with high values of the Enhanced Vegetation Index — a satellite-derived signal of dense, healthy primary forest. Intriguingly, the multi-scale models showed that chimpanzees responded to warm slopes at a broad 2-kilometre scale while selecting steeper terrain at a medium 250-metre scale, evidence that these apes integrate landscape features across nested spatial hierarchies. Nesting behaviour followed a subtly different recipe: slope was key, with a pronounced threshold at 15 degrees above which nesting suitability climbed, and landscape-scale topographic position and wetness at 2,000 metres featured prominently, indicating that elevated ground relative to surroundings provides the security these apes seek during their most vulnerable resting hours.

When the researchers intersected the predicted surfaces, the maps exposed a striking geography of risk. The western lowlands of the study area showed high hunting probability but low chimpanzee suitability, while the highest-elevation zones — precisely the steep, remote areas chimpanzees favour for nesting — emerged as the zones of greatest potential overlap between apes and hunters. Correlation analyses confirmed strong spatial associations between the predictive surfaces, meaning chimpanzees and hunters largely select and avoid similar terrain. The authors suggest this overlap may indicate that chimpanzees either tolerate human presence or employ temporal displacement, avoiding areas only when hunting activity is underway. Over the long term, however, sustained human activity in these shared zones could gradually suppress habitat use and force chimpanzees into increasingly marginal environments.

The most unexpected finding concerns the research camps themselves. Both chimpanzees and hunters avoided areas near the camps, but the hunters’ avoidance was markedly stronger. Because the reduction in predicted hunting activity exceeded the reduction in chimpanzee suitability, the camps effectively cast a protective buffer across the surrounding forest — a case of conservation science inadvertently shielding the very animals it studies. The authors caution, however, that this benefit comes with a caveat: because chimpanzees generally avoid humans, siting new camps in the heart of prime chimpanzee habitat could paradoxically drive the apes away from resources they need, so strategic placement must balance deterrence of hunters against disturbance of the studied communities.

Methodologically, the study offers lessons that extend well beyond Nimba. Scale-optimised boosted regression tree models consistently outperformed their single-scale counterparts, and the multi-scale approach improved the hunting models across both frameworks, confirming that habitat features invisible to single-scale analyses can prove critical for conservation planning. The two modelling approaches also diverged instructively: the linear models delivered clearer inference through model-averaged coefficients, while the machine learning models captured thresholds and extrapolated more reliably beyond surveyed ground. The authors are candid about limitations — survey effort targeted chimpanzee-frequented areas, potentially biasing the pseudo-absence sample, and variables such as fruit availability could not be included — and they call for extended surveys, ground-truthing and additional data on disturbances like slash-and-burn agriculture.

For the Mount Nimba Strict Nature Reserve, a UNESCO World Heritage Site listed as In Danger, the practical implications are immediate. High-elevation zones should be prioritised for intensive monitoring and patrolling, dense forests deserve protection as natural refuges, and the strategic positioning of research and monitoring infrastructure could be harnessed deliberately as a conservation tool. More broadly, the study demonstrates how pairing fine-scale remote sensing with multi-scale ecological niche modelling can turn scattered field observations into actionable maps of human-wildlife conflict — a template that, if replicated across other montane refuges, could help secure a future for the western chimpanzee in the fragmented forests of West Africa.

Subject of Research: The impact of illegal hunting on the spatial distribution of western chimpanzees in the Mount Nimba Strict Nature Reserve, Guinea

Article Title: Illegal Hunting and Chimpanzee Distribution in the Seringbara Region of the Mount Nimba Strict Nature Reserve: A Multi‐Scale Modelling Approach

Article References: Degrève, L., Erazo, D., Fitzgerald, M., Camara, H. D., Mamy, G., Dellicour, S., Kaszta, Ż., & Koops, K. (2026). Illegal Hunting and Chimpanzee Distribution in the Seringbara Region of the Mount Nimba Strict Nature Reserve: A Multi‐Scale Modelling Approach. Ecology and Evolution, 16(10), Article e74384. https://doi.org/10.1002/ece3.74384

Image Credits: AI Generated

DOI: 10.1002/ece3.74384

Keywords: western chimpanzee, Mount Nimba, illegal hunting, poaching, ecological niche modelling, boosted regression trees, habitat suitability, conservation, Guinea, UNESCO World Heritage, spatial overlap, multi-scale modelling

The scale of the gap the new inventory fills is striking. Global repositories of Aedes species occurrences, the datasets that scientists and health agencies around the world rely upon to model disease risk, had documented fewer than 200 unique locations for Kenya. That sparse coverage meant the country’s true Aedes diversity and distribution were largely invisible to the international surveillance community. Without accurate maps of where the vectors live, health authorities cannot effectively target the interventions that remain their primary line of defence. With no licensed vaccines against dengue or chikungunya available for use in Africa, vector control is currently the mainstay of prevention, making precise knowledge of species distributions not an academic luxury but an operational necessity.

To build the inventory, the research team, led by Samuel K. Muchiri of the KEMRI-Wellcome Trust Research Programme and including collaborators from the Kenya Ministry of Health, the Université Libre de Bruxelles, KU Leuven and the University of Oxford, deployed three complementary data-gathering strategies. The first was a systematic review of peer-reviewed literature, university theses and conference abstracts, following established systematic review reporting standards. The second, and ultimately the most productive, involved the digitisation of unpublished archival reports held by the Ministry of Health’s Division of Insect-Borne and Vector-Borne Diseases, as well as regional and municipal councils across the country. The third approach cross-referenced two major international repositories: the Global Biodiversity Information Facility, known as GBIF, and the Walter Reed Biosystematics Unit’s VectorMap database.

The contribution of the archival material proved to be the study’s most remarkable finding. Unpublished reports from government files accounted for 51 percent of all records in the final inventory, while peer-reviewed scientific articles contributed 43 percent. In other words, more than half of what is now known about Kenya’s Aedes fauna existed only in paper files and institutional memory, inaccessible to global databases and invisible to anyone modelling arboviral risk from published sources alone. The result is a powerful demonstration of how much critical surveillance data lies dormant in national archives across Africa, and a template for how it might be recovered elsewhere on the continent.

Once gathered, the data were handled with considerable technical care. Each record was extracted using a standardised template, then de-duplicated to remove repeated observations of the same occurrence. Geocoding, the process of assigning precise geographic coordinates to each record, was performed using Global Positioning System coordinates where available, Google Earth imagery for locations identifiable from place names and landscape features, or census enumeration area shapefiles for records tied to administrative units. This rigorous spatial processing transformed heterogeneous historical data, collected with wildly different methods and levels of precision over more than a century, into a single consistent database suitable for modern spatial analysis and ecological modelling.

The taxonomic results carry direct public health significance. Aedes aegypti, the principal vector of both dengue and chikungunya viruses, emerged as the most widely documented species in the country, recorded at 522 unique locations. The inventory distinguishes between the domestic form Aedes aegypti aegypti, which thrives in human-made containers and feeds readily on people, and the ancestral form Aedes aegypti formosus, which breeds in natural forest habitats. Beyond the principal vector, the researchers documented eight possible secondary vectors with confirmed field detection of dengue virus, chikungunya virus, or both. Among these, Aedes mcintoshi, Aedes ochraceus and Aedes tricholabis were the most frequently recorded, species associated with floodwater habitats that have featured in past Kenyan outbreaks.

Geographically, the inventory reveals both concentration and absence. Records cluster heavily along Kenya’s coast and in the western regions of the country, areas with longer histories of entomological investigation and denser human populations. By contrast, the northern and northeastern regions of Kenya show striking surveillance gaps, vast arid and semi-arid territories where Aedes mosquitoes may well circulate but where sampling has been minimal or nonexistent. These blind spots matter. Kenya’s northern counties border countries where arboviral transmission occurs, and the region’s episodic flooding creates ideal conditions for floodwater Aedes species. The inventory does not merely map what is known; it explicitly exposes where ignorance remains greatest, giving surveillance planners a prioritised agenda.

The database’s value extends well into the technical future of disease control. A geocoded inventory of this depth provides the essential empirical foundation for ecological niche modelling, the statistical framework that uses known occurrence points together with environmental variables such as rainfall, temperature and vegetation to predict where a species could survive. Models built on fewer than 200 occurrence records, as previous global datasets offered for Kenya, produce predictions too uncertain to guide policy. With 855 unique locations spanning 124 years, modellers can now capture seasonal and long-term variation, validate predictions against historical outbreaks, and generate sub-national risk maps precise enough to direct larval source management, insecticide-treated strategies and community-based container reduction programmes to the specific counties where they will have the greatest impact.

The timing of this work aligns with a broader global reckoning over arboviruses. The World Health Organization has elevated dengue and chikungunya among its priority concerns through initiatives such as the Global Arbovirus Initiative, as urbanisation, climate change and expanding mosquito ranges push transmission into new territories. Kenya has experienced documented dengue and chikungunya outbreaks in recent decades, particularly in coastal cities, and the viruses’ expanding footprint across East Africa makes national-level vector intelligence increasingly urgent. An inventory that integrates a century of evidence positions Kenya among a small number of African nations with the data infrastructure to anticipate, rather than merely react to, arboviral emergence.

Perhaps the study’s most transferable lesson is methodological. The researchers showed that a national inventory built from published literature alone would have captured less than half the available knowledge, and that digitising government archives, theses and conference abstracts can more than double the evidentiary base. The work was supported by the Wellcome Trust, including a Principal Research Fellowship and the Kenya Major Overseas Programme, alongside Belgian and European research funding, and the resulting database is offered as an open resource under a Creative Commons licence. For other countries confronting Aedes-borne disease with fragmentary surveillance records, the Kenyan model, systematic review plus archival rescue plus digital cross-referencing, offers a proven and comparatively low-cost pathway to the spatial evidence that modern vector control demands. The mosquitoes have been quietly mapping themselves across Kenya for more than a century; now, at last, science has caught up.

Subject of Research: A national geocoded inventory of Aedes mosquito species distributions in Kenya spanning 124 years of published, archival and digital surveillance data

Article Title: A national geocoded inventory of Aedes mosquitoes in Kenya: integrating published, archival, and digital sources across 124 years

Article References: Muchiri, S. K., Mwangi, L. W., Oloo, J., Omondi, W., Okiro, E. A., Rono, M. K., Dellicour, S., & Snow, R. W. (2026). A national geocoded inventory of Aedes mosquitoes in Kenya: integrating published, archival, and digital sources across 124 years. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07638-0

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07638-0

Keywords: Aedes aegypti, dengue, chikungunya, Kenya, mosquito surveillance, vector control, geocoding, ecological niche modelling, archival data, public health, arboviruses, Parasites & Vectors

The research team, led by Abhishek Gupta and Baleshwar Meena of CSIR-National Botanical Research Institute in Lucknow, together with colleagues from Banaras Hindu University and the Academy of Scientific and Innovative Research, sampled seven natural populations comprising 71 individual plants across the Western Himalayan Region. Rather than relying on a single line of evidence, the researchers integrated molecular marker data with species distribution modelling, an approach that conservation biologists increasingly favour because it captures both the biological richness of populations and the environmental context in which that richness evolved. The work was supported by a grant from the Department of Science and Technology’s Science and Engineering Research Board.

At the molecular level, the team deployed two complementary marker systems: 22 inter-simple sequence repeat markers, known as ISSR, and 11 directed amplification of minisatellite DNA markers, abbreviated DAMD. Both techniques amplify variable regions scattered across the genome, providing a rapid and cost-effective snapshot of genetic variation without requiring prior knowledge of the species’ DNA sequence. Together, the 33 markers revealed a cumulative polymorphism of 75.90 percent across the sampled individuals, meaning that roughly three-quarters of the detected genetic loci showed more than one variant. That figure suggests the species retains a meaningful reservoir of genetic diversity in the region, even though its populations are scattered across steep, fragmented terrain.

That overall diversity, however, was not evenly distributed. Populations designated KOK, BDR, and TND exhibited relatively higher genetic diversity, while populations SNM, GMK, and UDP showed comparatively lower levels. This unevenness matters for conservation because populations with reduced genetic diversity are more vulnerable to disease, environmental stress, and inbreeding depression, and they carry less raw material for adaptation to changing conditions. The researchers also quantified how genetic variation is partitioned across the landscape. A coefficient of genetic differentiation, GST, of 0.35 indicated substantial differentiation among populations, while an estimated gene flow value, Nm, of 0.88 pointed to only moderate exchange of genes between them. An analysis of molecular variance, or AMOVA, sharpened the picture further: about 70 percent of the total genetic variation resides within populations, with the remaining 30 percent occurring among them.

To visualize how the populations relate to one another, the team applied three independent clustering approaches: UPGMA, a distance-based tree-building method; principal coordinate analysis, which compresses genetic distances into a two-dimensional map; and Bayesian clustering, a statistical framework that assigns individuals to genetic groups based on allele frequencies. All three methods converged on the same answer: the sampled junipers belong to two major genetic clusters. The agreement among methods strengthens confidence in the result, since each technique carries different assumptions and potential biases. For conservation planners, the existence of two distinct clusters means that protecting representatives of both lineages is essential to preserve the full breadth of evolutionary heritage in the region.

The study went a step further by embedding the genetic data in a landscape context. Landscape genetics analysis supported isolation by distance as the primary driver of genetic differentiation, meaning that populations separated by greater geographic distances are also more genetically distinct, most likely because pollen and seed dispersal are limited over long distances in this rugged environment. Crucially, the analysis also identified potential dispersal corridors linking populations, pathways through the mountain landscape where gene flow could plausibly occur. These corridors offer a practical blueprint for conservation: maintaining or restoring connectivity along them could help counteract the genetic isolation that threatens small, fragmented populations.

On the environmental side, the researchers used ecological niche modelling to map where the species finds suitable habitat today and where it might persist in the future. The models identified four principal environmental determinants of the species’ distribution: precipitation of the driest month, elevation, isothermality, which measures how stable day-to-night temperatures are relative to seasonal variation, and the mean temperature of the wettest quarter. In plain terms, the alpine juniper depends on a delicate combination of winter-dry conditions, high altitude, and moderate thermal variability, precisely the conditions that climate change is expected to disrupt most rapidly in mountain systems, where species often have nowhere higher to go.

The projections are sobering. Under current climate conditions, the model estimates roughly 64,568 square kilometres of climatically suitable habitat across the region. When the models were projected onto future climate scenarios for the years 2060 and 2080, that suitable area declined, indicating an increased risk of habitat contraction. For a species already exhibiting high genetic differentiation and limited gene flow, shrinking habitat could trap populations on ever-smaller mountaintop islands, accelerating the loss of genetic diversity and raising local extinction risk. The findings echo a broader pattern documented for montane juniper species elsewhere in Asia, where endemic mountain conifers face elevated extinction risk under warming scenarios.

What makes this study valuable is not any single number but the convergence of evidence. The genetics reveal which populations are genetically rich and which are vulnerable; the niche models reveal where habitat is secure and where it is slipping away; and the landscape analysis reveals where corridors could reconnect fragmented populations. Together, these threads give conservation managers a prioritized action list: protect the genetically diverse populations at KOK, BDR, and TND as reservoirs of adaptive potential, closely monitor the low-diversity populations at SNM, GMK, and UDP, and safeguard the climatically suitable habitats identified by the models, particularly those that overlap with dispersal corridors.

The stakes extend beyond a single shrub. Juniperus communis has a long history of medicinal use, and its essential oils have been studied for antioxidant, antimicrobial, and neuroprotective properties, with prior work by members of the same research group documenting chemical variability among the western Himalayan populations. As a dominant element of alpine vegetation, the species also stabilizes soils and shelters other high-altitude organisms. Losing its genetic diversity would mean losing options, for ecosystem resilience, for future phytochemical discovery, and for the species’ own capacity to adapt. The study’s authors frame their results as a scientific basis for conservation prioritization in the western Himalaya, and in an era of rapid mountain warming, that basis could not have arrived at a more urgent moment.

Subject of Research: Population genetics and ecological niche modelling of common juniper in the western Himalaya

Article Title: Integrative analysis of population genetics and ecological niche modelling of common juniper (Juniperus communis L. var. saxatilis Pall.) in the western Himalaya, India

Article References: Gupta, A., Singh, H. C., Wairokpam, B., Singh, L. A., Dwivedy, A. K., Rana, T. S., & Meena, B. (2026). Integrative analysis of population genetics and ecological niche modelling of common juniper (Juniperus communis L. var. saxatilis Pall.) in the western Himalaya, India. 3 Biotech, 16(9), Article 403. https://doi.org/10.1007/s13205-026-05023-3

Image Credits: AI Generated

DOI: 10.1007/s13205-026-05023-3

Keywords: Juniperus communis, population genetics, ecological niche modelling, western Himalaya, ISSR markers, DAMD markers, genetic diversity, climate change, habitat suitability, conservation genetics, gene flow, alpine plants

The study, published in Nature Climate Change, tackles one of the most stubborn problems in conservation science: attribution. Pollinating insects face a gauntlet of modern pressures, from agricultural chemicals to habitat fragmentation to parasites such as the bee-processing pathogen Crithidia bombi and spillover from managed honeybees. When a bumblebee population vanishes from a landscape, which of these culprits deserves the blame? Traditional correlative studies cannot easily answer that question, because climate trends move in lockstep with many other environmental changes. The Belgian-led research team, headed by Bastien De Tandt of the Université Libre de Bruxelles and the University of Mons, sidestepped the problem with a counterfactual design borrowed from the climate attribution community.

Technically, the approach rests on running the same ecological models twice. First, the team trained ecological niche models for forty-seven European bumblebee species using occurrence records drawn from a newly synthesized database of wild bee and hoverfly observations across Europe, combined with climatic variables from the ISIMIP3a reanalysis framework, which reconstructs historical weather conditions from 1901 to 2019. These models, built with boosted regression trees, learn the environmental envelope each species occupies, capturing the temperature and precipitation conditions under which bumblebees persist. Performance was validated with spatially blocked cross-validation and metrics including the area under the receiver operating characteristic curve and a prevalence-calibrated Sørensen index, guarding against the optimism that plagues purely random data splits.

Then comes the counterfactual. Using the ATTRICI method, the researchers constructed a parallel climate dataset in which long-term anthropogenic trends have been removed while natural year-to-year variability is preserved. In this counterfactual Europe, weather still fluctuates and seasons still turn, but the warming fingerprint of industrial society is erased. Feeding both datasets through identical niche models produced two parallel histories of habitat suitability, and their difference isolates the specific contribution of human-caused climate change. It is the ecological equivalent of a clinical trial with a control group, and it gives the results a causal weight that earlier correlational studies of bumblebee decline could not claim.

The verdict is sobering but geographically nuanced. At the continental scale, community-level ecological suitability, a measure averaging suitability across all forty-seven species, fell by roughly five percent under the factual climate relative to the counterfactual one. But that continental average conceals sharp regional contrasts. Southern Europe, already identified as a Mediterranean climate-change hotspot in CMIP5 and CMIP6 projections, suffered the steepest declines, with suitability losses reaching nineteen percent locally. Lowland central regions, including the Carpathian Basin and the surrounding plains, also registered pronounced erosion of suitable conditions. These are areas where summer heat extremes have intensified faster than many climate models simulate, and where bumblebees, evolutionarily adapted to cool temperate conditions, bump against their physiological limits.

Bumblebees are, in a sense, mammals of the insect world: thick-furred, cold-adapted descendants of alpine lineages that struggle when temperatures climb. Laboratory protocols developed to test insect heat tolerance have shown that many Bombus species have critically low thermal maxima compared with other insects, and heat waves have been linked to a ‘scarcity syndrome’ of local disappearances documented in France as far back as the early 2000s. The new results suggest those anecdotal local extinctions are the visible edge of a continent-wide redistribution of livable space. As conditions warm, the suitable zone shifts poleward and upward, and species unable to disperse fast enough accumulate a mounting climatic debt.

The mountain and boreal edges of Europe tell a different story. In the Alpine and Boreal biogeographic regions, gains in suitability at higher altitudes and latitudes partially compensated for losses at lower elevations, yielding minimal net change. Cold-adapted species such as Bombus alpinus have shown hints of uphill shifts in the Alps, and bumblebee elevation ranges have climbed measurably in the Pyrenees over the past century. Yet researchers caution that these apparent refuges are finite. Mountains are truncated worlds: a species can only climb so far before it runs out of summit. The modest boreal gains also reflect expansions of a few generalist species, including the tree bumblebee Bombus hypnorum, rather than a broad story of resilience.

What makes the findings particularly consequential is what they imply for the rest of the century. An earlier analysis by overlapping authors projected steep declines in European bumblebee populations through 2100 under future warming scenarios. The new attribution study confirms that the projected future has, in a quantifiable sense, already begun. Climate change is not a looming threat to these pollinators; it is a pervasive, measurable pressure that has been reshaping their distributions for more than a hundred years, compounding the stresses of intensive agriculture, pesticide exposure and dwindling floral resources. Because bumblebees pollinate a large share of wild flowering plants and numerous crops, including tomatoes, berries and legumes that depend on their distinctive buzz pollination, the erosion of their habitat carries direct consequences for both biodiversity and food production.

The methodological template established here is likely to spread. Counterfactual climate datasets and impact-attribution frameworks of the kind used in the Inter-Sectoral Impact Model Intercomparison Project are increasingly available, and the researchers have released their curated occurrence database, models and R scripts openly through Zenodo and GitHub. Similar attribution exercises could now disentangle climate’s role in the fortunes of other threatened insect groups, from hoverflies to butterflies, where blame has been similarly contested. For conservation planners, the regional maps of climate-driven suitability loss offer a practical tool: southern and central lowland populations emerge as priority targets for habitat restoration, connectivity corridors and thermal refugia, while mountain reserves gain added strategic value as potential stepping stones in a warming race. The study’s authors note that all datasets underpinning the work are freely available, and their results demonstrate unambiguously that climate change is already rewriting the map of Europe’s most beloved wild pollinators.

Subject of Research: Attribution of declines in European bumblebee habitat suitability to human-driven climate change since 1901

Article Title: Declines in European bumblebee habitat suitability attributable to climate change

Article References: De Tandt, B., Serres, K., Pietroiusti, R., Erazo, D., Massonnet, F., Michez, D., Thiery, W., Ghisbain, G., & Dellicour, S. (2026). Declines in European bumblebee habitat suitability attributable to climate change. Nature Climate Change. https://doi.org/10.1038/s41558-026-02734-6

Image Credits: AI Generated

DOI: 10.1038/s41558-026-02734-6

Keywords: bumblebees, climate change, habitat suitability, pollinators, ecological niche modelling, counterfactual climate, attribution, biodiversity loss, Europe, Nature Climate Change, conservation biology, ISIMIP3a