The research team turned to MaxEnt, short for maximum entropy modelling, one of the most widely used tools in modern biogeography. The technique works by comparing the environmental conditions at locations where a species has been recorded with the conditions available across the whole study area, then estimating the probability of occurrence at every grid cell. Rather than requiring absence data, which is notoriously unreliable, MaxEnt builds a picture of a species’ ecological niche from presence records alone. For a country as topographically and climatically varied as Algeria, which spans Mediterranean coastline, high plateaus and the northern fringe of the Sahara, this approach is particularly powerful because it can capture the full breadth of conditions a species tolerates.

To drive the models, the researchers assembled occurrence records for both oak species, drawing on field knowledge and global biodiversity databases, and combined them with a suite of environmental predictor variables covering temperature, precipitation and terrain. Crucially, they projected the models forward using future climate scenarios for three time horizons, allowing them to track not just whether habitat will be lost or gained, but where the geography of suitability will shift. The performance of the models was assessed using the Area Under the Curve, or AUC, a standard statistical measure of discrimination. Values above roughly 0.8 are generally considered good, and above 0.9 excellent. Both oak models exceeded 0.96, a strikingly high score that indicates the models separated suitable from unsuitable terrain with near-perfect reliability.

The single most influential variable shaping the distribution of both species was the Martonne aridity index, a classic climatic measure that combines annual precipitation with mean temperature to express the degree of water availability across a landscape. Its dominance in the models makes ecological sense. Mediterranean oaks live at the dry edge of what trees can tolerate, and their growth, survival and regeneration are tightly governed by the balance between water arriving as rain and water lost to the atmosphere. In Algeria, where warming is outpacing the global average and droughts are becoming more frequent and severe, this finding underscores that aridity, not temperature alone, is the master variable controlling the fate of these forests.

When the researchers projected the models into the future, the two species told different stories. For cork oak, the annual rate of highly suitable habitat is expected to decline under every future scenario, with projected losses ranging from 0.040 percent to 0.191 percent per year. The numbers may look small, but compounded over decades they translate into a meaningful contraction of the species’ core range in Algeria. Cork oak is already under pressure across the western Mediterranean from land abandonment, overgrazing, fire and unexplained decline phenomena, so any additional climatic squeeze on its best habitat is cause for concern for foresters and conservationists alike.

Holm oak, by contrast, showed far greater stability. Its highly suitable habitat is projected to change only slightly, with shifts ranging from a loss of 0.021 percent to a gain of 0.164 percent per year depending on the scenario. This hardy evergreen is famously drought-tolerant, capable of surviving on thin soils and withstanding long summer dry seasons, and the model results reflect that toughness. In practical terms, the study suggests that holm oak could even hold its ground or modestly expand in some parts of Algeria as conditions change, making it a candidate species for stabilising forests in an increasingly arid landscape.

Perhaps the most vivid finding concerns elevation. The average elevation of suitable habitat is projected to shift under each climate scenario, ranging from 866 to 1,025 metres for cork oak and from 978 to 1,172.5 metres for holm oak. In other words, as the lowlands warm and dry, the climatic comfort zone for both species climbs the mountainsides, and holm oak consistently occupies higher ground than cork oak. This pattern echoes a well-documented global phenomenon in which mountain plant communities shift upslope in response to warming. The catch, as ecologists have repeatedly warned, is that mountains are cones: the higher a species climbs, the less land remains available, and slow-moving trees may lag far behind the pace of climate change.

The models also revealed a striking directional signature. Under most future scenarios, the highly suitable habitat for cork oak shifts towards the northeast of the country, while for holm oak it shifts towards the northwest. These compass bearings matter enormously for conservation planning. Northeastern Algeria, with the humid coastal ranges of Kabylia and El Kala, retains some of the wettest conditions in the country, and the projected northeastward drift of cork oak suitability suggests these areas will become increasingly critical refuges. The northwestward shift for holm oak points to a different set of priority landscapes, and the divergence between the two species means that a single, one-size-fits-all protected area network will not serve both trees equally well.

The practical value of this work lies in its maps. By identifying where habitat is highly suitable now and where it is likely to remain suitable through the end of the century, the study gives Algerian foresters a decision-support tool of real consequence. Rather than reacting to forest decline after it happens, managers can use these projections to prioritise which forest stands to protect, where to focus regeneration efforts, and which zones should be preserved as climate refugia. The authors emphasise that the maps are intended precisely for this purpose: helping foresters select the best conservation strategy for cork oak and holm oak and choose appropriate forest zones to be preserved before the climate window closes.

The study also sits within a growing body of Algerian research on climate-driven range shifts, including recent work on Atlas cedar, Aleppo pine, Phoenician juniper and the endemic oak Quercus afares, all pointing in a consistent direction: the country’s forest flora is being reshuffled by warming and drying. What makes the new findings compelling is the contrast between two closely related, sympatric oaks responding so differently to the same climatic pressures. As the Mediterranean basin warms faster than the global average, the fate of these forests will depend on whether conservation planning can anticipate the movement that the models now make visible. For Algeria’s cork and holm oaks, the future is not yet written, but the map of where it will unfold has finally been drawn.

Subject of Research: Species distribution modelling of cork oak and holm oak habitats in Algeria under climate change

Article Title: Modelling the current and future potential distributions of Quercus suber and Q. ilex (Fagaceae) in Algeria

Article References: Rais, H., Laala, A., Meghzili, I., Mennour, H., & Boucenna, H. (2026). Modelling the current and future potential distributions of Quercus suber and Q. ilex (Fagaceae) in Algeria. Plant Biosystems, 160(5), Article 239. https://doi.org/10.1007/s44473-026-00241-2

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00241-2

Keywords: Quercus suber, Quercus ilex, Algeria, MaxEnt, species distribution modelling, climate change, aridity index, habitat suitability, Mediterranean forests, cork oak, holm oak, forest conservation

The groundwork for this groundbreaking research began decades ago, with the meticulous collection of 13,000 grasshopper specimens atop a Colorado mountain by biologist Gordon Alexander during the late 1950s. This critical dataset lay dormant for many years following Alexander’s tragic death in a plane crash in 1973. It was not until 2005 that postdoctoral fellow César Nufio resurrected this repository of knowledge, recognizing its potential to illuminate the intricate interactions between climate change and insect physiology.

Nufio led a new survey to gather contemporary samples from the same sites where Alexander had once worked. This initiative illuminated the evolutionary legacy of environmental change by comparing findings from over half a century past with those of today. Collaborating with fellow biologists from esteemed institutions, including Caroline Williams at UC Berkeley and Lauren Buckley at the University of Washington, the team investigated the size variations in several grasshopper species and how these alterations relate to climate fluctuation and seasonal timing.

The findings published in the journal PLOS Biology shed light on a remarkable phenomenon: while climate change has instigated size reductions in some grasshopper species, others have adapted by growing larger. This paradox is principally observed among the nymphal diapausers—grasshoppers that spend winter in a juvenile state and can commence feeding earlier in the spring. This early start enables them to thrive on the lush greenery that emerges with the thawing of winter. Conversely, the egg diapausers, hatching in the spring from eggs laid in the fall, have shown a substantial decline in size, likely due to deteriorating vegetation and altered growth patterns.

Williams and her colleagues methodically analyzed factors like elevational gradients, timing of life stages, and historical records of environmental conditions to draw their conclusions. Their projections hinted at varying fates for different species, driven by their ecological niches and life cycles. This research reiterates the importance of nuanced understanding in ecological forecasting, highlighting that outcomes can shift within species depending on environmental contexts.

Surprisingly, as climatic conditions worsen, nymphal diapausers thrived at lower elevations, where warmer summers provided ample resources. Yet, life was harsher for the grasshoppers hatching from eggs at higher altitudes. Data from the study suggests that, in these conditions, larger snowcaps may inhibit early food production, stunting growth. Therefore, the researchers emphasize that the challenge of predicting the consequences of climate change on individual species requires a multidimensional approach that takes into account various factors including temperature variability and elevation.

This innovative research utilizes the invaluable historical specimens from museum collections, allowing scientists to make direct comparisons over time without the interruptions caused by shifts in land use or experimental methodologies. The results of this study may serve as a beacon for future research, demonstrating that well-curated historical data can provide essential context for understanding current biodiversity trends.

In a broader context, the study’s findings resonate with observations across multiple species, including other invertebrates and vertebrates. Buckley points out that similar size adaptations have been noted in butterfly populations, implying that the principles gleaned from grasshopper studies could extend to other species facing climate pressures. This cross-species consistency enhances the predictive capabilities of ecologists striving to assess the broader implications of climate change on ecosystems.

Continued collaboration among the researchers is vital as they delve deeper into the metabolic, biochemical, and genetic adaptations associated with size variation in the face of climate change. Their work exemplifies the vital intersection of evolutionary biology, ecology, and climate science, necessitating interdisciplinary dialogue to address the pressing challenges posed by environmental transformation.

As this research unfolds, the implications of its findings beckon urgent action. Predicting which species may adapt successfully and which may falter remains a formidable task. Yet, through dedicated studies grounded in historical data and ecological principles, the door opens for more informed conservation strategies that could mitigate the impacts of climate change on biodiversity.

Success in these endeavors may not only illuminate the shadows cast by climate change on current ecosystems but also equip future generations of biologists and ecologists with the tools they need to navigate the uncertainties ahead. The challenge remains, but through careful examination of the past and an eye toward future possibilities, researchers can strive to design resilient ecosystems capable of withstanding the pressures of our warming world.

The legacy of Gordon Alexander’s collection serves as both a reminder of the value of meticulous scientific work and as an inspiration for future studies. Each grasshopper tells a story not only of its species but of an entire ecosystem adapting to a dynamic environment. As climatic forces continue to reshape our world, such research may prove crucial for understanding the myriad responses of life on Earth.

Subject of Research: Animals

Article Title: Insect size responses to climate change vary across elevations according to seasonal timing

News Publication Date: 30-Jan-2025

Web References: DOI Link

Image Credits: Credit: Thomas Naef, 2022

Keywords: Climate Change, Grasshoppers, Insect Size, Colorado, Adaptation, Biodiversity, Ecology, Evolution, Metabolic Response, Seasonal Timing, Museum Collections, Conservation.