Climate change is increasingly disrupting ecological processes across arid and mountainous biomes, with profound implications for the reproductive phenology of large herbivores. These species are especially climate-sensitive, as their breeding cycles are tightly coupled with vegetation dynamics driven by seasonal temperature and precipitation. Yet, in biodiversity-rich regions such as eastern Iran, where climate variability is acute and data are sparse, long-term phenological responses remain poorly understood. Here, we examine how reproductive timing in urial sheep (Ovis vignei), a mountain herbivore, responds to climatic variation across six protected areas, as climate-driven mismatches between birth timing and peak forage availability may reduce neonate survival and ultimately affect population viability and connectivity. Climate data (temperature, precipitation, snowfall, and humidity) from the nearest weather station to each study area, along with latitude and mean elevation of each habitat, were integrated using generalized linear mixed models (GLMMs) to assess phenological responses to environmental variables. Our results reveal clear regional differences in mating and lambing time. Mating time was significantly influenced by latitude, summer temperature, and autumn precipitation, with higher latitudes and autumn rainfall delaying mating, while warmer summers advanced it. In contrast, lambing timing was largely dictated by study area-level random effects, which accounted for the majority of variance, whereas fixed effects such as January temperature, snowfall, and latitude contributed only minimally, highlighting the dominant role of spatial differences among study areas in shaping lambing phenology. These findings, over the past decade, underscore the role of climate and latitude in shaping reproductive timing and highlight the urgent need to incorporate phenological data into adaptive wildlife management and habitat-specific climate resilience planning in vulnerable arid mountain ecosystems.

Species respond to climate change through phenological and spatial shifts. Herbivorous mammals, in particular, are vulnerable due to their direct dependence on seasonal vegetation and the potential misalignment between their reproductive cycles and shifting food availability. This study examines the influence of temperature, rainfall, and humidity on the timing of mating and calving in wild and semi-captive populations of Caspian red deer Cervus elaphus maral along the southern Caspian Sea. Our results reveal that in wild populations, rising temperatures from 1 September to 31 May led to earlier calving, while warmer conditions from 1 June to 31 August advanced mating. In contrast, no significant phenological shifts were observed in semi-captive populations, likely due to supplemental feeding and environmental buffering. These findings suggest that climate-induced reproductive changes may threaten the long-term viability of the Caspian red deer, particularly as habitat fragmentation limits access to cooler, higher-altitude refuges. Conservation efforts should prioritize habitat protection and connectivity in mountainous regions to support population resilience under ongoing climate change.

Wildfire activity in the Southern Zagros, Iran, has increased in recent decades, posing potential risks to vertebrate biodiversity. This study evaluates the spatial overlap and exposure of biodiversity to recurrent wildfires using satellite data with 13,419 fire events from 2000 to 2023. 6140 fire events were recorded between 2021 and 2023, nearly equaling the number documented from 2000 to 2020. Spatio-temporal clustering with SaTScan identified six fire clusters, largely coinciding with areas of high species richness. Species distribution modeling (MaxEnt) was applied to 108 vertebrate species to map habitat value and assess exposure. Fire-prone zones were concentrated at mid-elevations (1000-2500 m) with dense vegetation, and seasonal peaks occurred in spring and summer. Fire occurrence was positively associated with human infrastructure, including roads and settlements. Approximately 60% of the burned area fell within high-value ecological zones, encompassing the ranges of 29 Red Listed vertebrate species, of which 22 have potential distributions within the fire clusters. Limitations include the lack of pre-and post-fire species data, which suggests that the study focuses on exposure and spatial overlap. These findings highlight the importance of targeted fire management and conservation planning in biodiversity-rich, high-risk regions of the Southern Zagros.

Iranian Barbel taxonomy and evolutionary history (Cyprinidae: Barbinae and Torinae) remain contentious due to overlapping morphological traits and limited molecular data. This study applies an integrative taxonomic framework to elucidate species boundaries, phylogenetic relationships, and the environmental drivers of diversification within Barbels lineages across Iran. We analyzed mitochondrial DNA (Cytb and COI genes), seven meristic morphological characters, and five spatial environmental predictors from specimens collected across localities representing major Iranian basins. Phylogenetic reconstructions using Maximum Likelihood and Bayesian Inference revealed three main monophyletic groups: (1) Arabibarbus, Mesopotamichthys, and Carasobarbus (Torinae); (2) Luciobarbus; and (3) Barbus sensu stricto (Barbinae). Principal Component and Canonical Variate Analyses of meristic data corroborated molecular findings, supporting the delineation of this taxa. Ecological Niche Evolution analysis indicated several species occupy similar climatic niches, suggesting parallel evolutionary responses to environmental pressures. Divergence time estimates and lineage-through-time analyses linked major cladogenic events to regional orogeny and Quaternary climatic fluctuations. Species delimitation analyses suggested potential synonymy among specific taxa (e.g., L. capito with L. conocephalus; L. esosinus with L. xanthopetrus), highlighting the need for taxonomic revision. Our integrative approach demonstrates that geological history and climatic factors have shaped the diversity and distribution of Barbels in Iran. These findings provide a robust framework for future taxonomic, conservation, and biogeographic studies of Iranian freshwater fishes.

Agriculture remains the dominant consumer of freshwater globally, with projected increases in demand driven by irrigation expansion. In arid regions such as Iran, this intensifies competition among agriculture, industry, and ecosystems, exacerbating water stress-as evidenced by the desiccation of Tashk-Bakhtegan wetlands in Fars Province, a key source of dust storms affecting local communities. This study employs system dynamics modeling and the Water Resource Carrying Capacity (WRCC) framework to assess four degrowth scenarios focused on rice and wheat cultivation, evaluating their effects on water consumption and economic value-added. Results show that eliminating rice production and reducing wheat cultivation by 10 %, or converting 20 % of irrigated wheat to rainfed farming, yielded only marginal improvements in the Water Resource Carrying Capacity (WRCC) index. Reaching a sustainable WRCC demands at least a 25 % reduction in agricultural water withdrawals, with an associated 13 % decline in economic output. These findings highlight a nonlinear trade-off between environmental recovery and economic loss. By benchmarking extraction levels against ecological thresholds, this modeling framework promotes adaptive and equity-centered water governance in arid regions. It also provides strategic insight for long-term agricultural and industrial planning.

Previous studies have shown instances where aquatic ecosystems in Iran have experienced water loss even in the absence of upstream dams, while other ecosystems with upstream dams did not show significant declines in water levels. Thus, attributing the drying of these ecosystems solely to climate change in the watershed is not definitive, especially when water levels behind dams have increased while wetlands’ water volumes decreased due to water diversion. This complexity underscores the challenge of linking the decline of aquatic ecosystems exclusively to climate change, as reduced rainfall would naturally lead to decreased water levels behind dams as well. This study addresses this complex issue by analyzing 60 water bodies behind dams across various regions of Iran from 2013 to 2023, using Landsat 8 satellite images and the AWEIsh water index. We employed linear regression to detect surface change trends during this period. Our findings revealed statistically significant (P-value < 0.05) trends in 13 out of the 60 water bodies, with four showing an increasing trend in water levels, indicating diverse precipitation patterns across Iran rather than a uniform decline. Among these, nine dams with significant trends experienced decreased water levels, reflecting reduced upstream rainfall in their watersheds over the past decade. This supports existing research highlighting climate change’s impact on Iran’s water resources. Despite highlighting the impact of declining precipitation and increasing temperatures in certain regions, our study also reveals that certain areas in Iran have not faced such severe conditions. In fact, some regions have seen a notable increase in dam water levels over the past decade. This study emphasizes the importance of an impartial assessment of Iran’s water reserves, free from preconceived notions from previous studies. Such an objective evaluation is crucial for effective management of Iran’s water resources.

This study aims to examine the evolving network of corridors resulting from climate change and the emergence of new barriers affecting Canis aureus. We employed species distribution models (SDMs) to evaluate the potential effects of climate change on Canis aureus under both current and future SSP585 climate scenarios for the year 2070. We utilized the Linkage Mapper tool to identify the least-cost paths under two climate scenarios. We discovered 20 core habitat areas with an average size of 29791 km2 for this species, with Linkage Mapper detecting 34 links between them with an average length of 84.3 km in the current scenario. In contrast, we identified 20 core habitats with an average size of 6091 km2 under the future scenario, showing changes in their positions. We identified 39 links between them, averaging 50.4 km in length. There are 145 road intersections in the current scenario, which decreases to 87 in the future scenario. The overlap of least-cost paths with cropland areas decreases from 974 to 589, and with urban areas, it decreases from 72 to 50 in the future. Our research underscores the pressing necessity for conservation initiatives to mitigate climate change's repercussions on mammal habitats and corridors in Iran, highlighting the potential impact of our findings on future conservation strategies.

Climate change and habitat loss are among the most significant threats to global biodiversity, profoundly altering species distributions, reproductive success, and the number of individuals. This study focuses on the Caspian red deer (Cervus elaphus maral) within the Golestank core zone of the Central Alborz Protected Area (CAPA), investigating how climatic variables and conservation interventions have influenced their numbers over the past two decades. By integrating comprehensive field surveys, demographic assessments, and weather data from regional weather stations, we identified a consistent annual growth rate of 2.2%. This positive trend is attributed to enhanced calf survival and a stable male-to-female ratio, reflecting the population's resilience under conservation management. Warmer winter temperatures were found to positively influence population numbers, whereas increased spring snowfall exerted a detrimental effect. These findings highlight the importance of targeted habitat conservation efforts to buffer the impacts of climate change and support long-term population sustainability.

Seed dispersal through endozoochory plays a fundamental role in maintaining plant population dynamics, genetic connectivity, and habitat resilience, particularly in mountainous biodiversity hotspots. Large herbivores and omnivores can facilitate this process by transporting viable seeds across fragmented landscapes. However, the functional differences in dispersal capacity between native and domestic herbivores remain poorly understood. This study compares the seed dispersal effectiveness of three native large mammals Caspian red deer (Cervus elaphus maral), wild goat (Capra aegagrus), and brown bear (Ursus arctos syriacus) with domestic sheep, within the Central Alborz Protected Area (CAPA), northern Iran. From 226 scat samples collected across elevations of 2300–3850 m, 264 seedlings belonging to 40 plant species germinated. Brown bears showed the highest dispersal effectiveness (IEd = 46.6), dispersing seeds of 14 species from 100 plant bases across 30 samples. Red deer followed (IEd = 23.1; 117 plant bases; 18 species; 91 samples), with wild goats (IEd = 3.3) and domestic sheep (IEd = 2.5) ranking lower. Plant species overlap among animal groups was minimal, with the highest similarity between brown bear and domestic sheep (IM = 0.089), and no overlap between red deer and wild goat. Native large mammals are key contributors to the dispersal of diverse native and endemic plant species in CAPA. In contrast, domestic sheep exhibit low dispersal effectiveness and tend to propagate non-native or invasive flora. These findings underscore the ecological importance of preserving native large mammal populations and implementing rewilding and grazing management strategies to safeguard plant diversity and ecosystem function in alpine environments under increasing anthropogenic pressure.

In concert with climate change, our planet faces unprecedented biodiversity loss, with half of all species at risk of extinction. Despite global conservation efforts, the biodiversity crisis continues to outpace these actions. The Global Biodiversity Framework seeks to halt this trend by expanding protected areas (PAs) to cover 30 % of terrestrial and aquatic environments by 2030. Conservation gap analysis, based on species distribution models (SDMs), is vital for assessing the effectiveness of PAs under future climate scenarios. However, traditional gap analysis often relies on binary predictions, leading to critical information loss and failing to target multiple species groups simultaneously or address dynamic species distributions. To overcome these limitations, we propose a refined gap analysis method using a fuzzy approach with machine learning models. Our method incorporates multiple species groups, dispersal scenarios, and uncertainty assessments, offering improved conservation planning. We applied this approach to amphibians-a taxon highly vulnerable to climate change-and evaluated PA effectiveness and potential refugia under various future scenarios. Our findings show that while approximately 60 % of amphibians currently protected by PAs may continue to find refuge, their average habitat suitability is expected to decline significantly under future conditions, indicating potential losses in PA effectiveness. Our refined fuzzy gap analysis captures a continuous spectrum of habitat suitability, facilitates species comparability, and integrates multiple conservation targets. This approach provides a robust tool to guide biodiversity strategies, ensuring that conservation efforts are more adaptive, resilient, and precise in the face of climate change uncertainties.

Many forest ecosystems are becoming more vulnerable due to human activities and the considerable effects of forest exploitation. Furthermore, forest management practices often overlook the importance of biodiversity, focusing primarily on timber production and economic gain. The Hyrcanian forests, in particular, face significant challenges due to a combination of factors such as deforestation, climate change, and invasive species. This study aims to explore the impact of reforestation on the diversity, abundance, and community structure of two key groups of soil engineers: earthworms and ants. These groups were chosen due to findings from a previous study indicating their higher abundance in this region. Additionally, it aims to determine which of these groups is more significantly impacted. The study was conducted in both natural and planted forests across three locations in the central region of these forests. Samples were collected from 72 quadrats and 48 transects. A total of 251 samples were collected for earthworms and 410 samples for ants. Then, the samples were sorted into morphological operational taxonomic units (MorphOTUs) based on morphological characteristics. DNA barcoding studies were performed using the cytochrome c oxidase subunit 1 (COI) gene to determine the molecular OTUs. After that, the difference in OUT richness, abundance and composition between natural and planted forests was investigated using statistical analysis. In the current research, 16 and 19 OTUs were recognized for earthworms and ants, respectively. The results indicated that ant abundance was significantly higher in natural forests (n = 263) compared to planted forests (n = 147). However, the difference in earthworm numbers was negligible (n = 125 in natural and n = 126 in planted forests). The community compositions of both groups did not show significant differences between these forests. The difference between ants and earthworm abundance indicates that ants play a key role as pioneer species in the colonization process, followed by other groups (earthworms) that have settled in the planted forests. The study emphasizes the significance of a genetic approach to understanding the biodiversity of both groups. We believe that integrating both groups will improve the effectiveness of bioindicators in these areas. It is crucial to recognize the biodiversity of soil invertebrates for monitoring natural forests and developing effective reforestation policies, which are essential for fostering resilient ecosystems.

Freshwater ecosystems, being highly susceptible to the impacts of climate change, experience a greater influence than terrestrial and marine ecosystems. Hence, by identifying the regions that will be most affected by climate change in the future, managers can implement more efficient and effective measures to protect them. In this study, we utilized six Luciobarbus species residing at the southernmost boundary of their global distribution as a representative species model. We aimed to evaluate the influence of climate change on the distribution of these key species to identify potential future climate refuges within the Tigris–Euphrates basin and use the richness mapping method to determine the most critical driver of their richness pattern for high-priority conservation. In the current study, using an ensemble approach, we modeled the potential impact of climate change on the distributions of six Luciobarbus species by the years 2061–2080 and 2081–2100 under two Shared Socio-economic Pathways (SSPs) of general circulation models (GCMs). We employed a generalized linear model (GLM) with a quasi-Poisson distribution to create a map depicting the richness of Luciobarbus fish species.Our projections indicate that suitable habitats will decline in both time series under climate change SSP126 and SSP585 scenarios, resulting in the loss of certain habitat patches in the Southwest of Iran, Syria and Iraq. The result of the species richness map shows the southern region of the Tigris–Euphrates basin has the highest number of species. Furthermore, temperature was the most critical predictor of Luciobarbus fish richness in the basin. Implementing significant strategies, such as identifying areas with the highest species richness and susceptibility to climate change, is essential to conserving and managing key species like Luciobarbus. Additionally, establishing protected areas in suitable landscapes and preserving critical habitat patches as future climate refuges are crucial. These measures will contribute significantly to the conservation and management of freshwater species.

The goitered gazelle (Gazella subgutturosa), historically widespread across the Middle East and Central Asia, is now facing a critical threat due to habitat fragmentation and population decline, particularly in Iran. To better understand the reason for the low genetic diversity of goitered gazelle populations, we combined a genetic analysis (cytb gene) like genetic diversity and demographic history using non-invasive sampling techniques with a land use/land cover study by land use dynamic degree models (LUDD) and landscape change process analysis. The selection study area is based on several populations of goitered gazelle that are located on the southern slope of the Alborz Mountain range in Iran. The results showed an alarming paucity of nucleotide diversity (0.0019) within these populations. At the same time, analysis of land use and land cover changes in the same area showed that over the past 30 years (1990-2020) urban areas have had the most increase among other land use classes (growth rate: 171%). The knowledge acquired from this research not only contributes to our understanding of the genetic makeup of goitered gazelle populations but also underscores the importance of addressing land use changes and their consequences on biodiversity. These findings emphasize the need for targeted conservation efforts to counteract the effects of urban growth on goitered gazelle habitats. Such strategies are crucial for securing the future of these populations in the southern slopes of the Alborz Mountain range and similar regions facing similar pressures.

Climate change significantly impacts species distributions and adaptability. This study investigates the evolutionary history, genetic variation, and potential distribution shifts of the Caspian bent-toed gecko (Tenuidactylus caspius) in Iran under past, present, and future climate conditions. Phylogenetic analysis revealed two distinct subclades within T. caspius, which diverged approximately 1.14 million years ago. Despite this divergence, distinct subclades were not observed in terms of notable differentiation, as the species showed low genetic diversity, with only nine haplotypes and limited nucleotide variation. Population size remained relatively constant over time, with a slight recent decline. Biogeographic analysis indicated a complex history of dispersal and vicariance events. Species distribution modeling suggests a historically wider range, with a northward expansion during the Last Glacial Maximum. The current range is reduced, and future projections (2061-2080) indicate a further decline, especially in marginal areas, with the eastern range becoming the core habitat. The low genetic diversity raises concerns about the species' adaptability to climate change. Conservation efforts should focus on protecting existing populations, particularly in the eastern range, and maintaining habitat connectivity to support gene flow. This study highlights the importance of integrating genetic and historical data for effective conservation planning in the context of climate change.

Climate change poses a significant global challenge, profoundly affecting species distribution. In recent years, research focusing on the impacts of climate change on freshwater taxa has been relatively limited compared to studies on terrestrial taxa. This study seeks to identify hotspots and occurrences of all Carasobarbus freshwater fish species while also predicting the potential implications of climate change through the use of ensemble species distribution modeling (ESDM). Analyze climatic changes across various temporal scales: the Mid- Holocene (6000 years BP), the Last Glacial Maximum (21,000 years BP), the present, and future projections (2061-2080). Global circulation models (GCMs) showed strong predictive capabilities for the species climatic niches, with Area under the curve (AUC) and true skill statistics (TSS) values. Key predictors included Annual Mean Temperature, Mean Temperature of the Driest Quarter, and Precipitation of the Driest Month. The analysis revealed varied responses to climate change: Five and seven species are expected to lose climatically suitable habitats (losers) in SSP 126 and SSP 585, respectively, indicating heightened vulnerability, in SSP126 and SSP 585 four and three species are expected to see an increase (Winners) in their range respectively, and additionally, in SSP 126 and SSP 585 two and one species are anticipated to maintain approximately stable (Under 1 % change) distributions within their ranges under the specified scenarios. Additionally, the Iran-Anatolian hotspot emerges as crucial for Carasobarbus populations globally. The research highlights the effects of climate change on Carasobarbus distribution patterns, providing essential insights for conservation strategies and management to protect biodiversity in vulnerable regions.

The history of the formation of the Tigris-Euphrates basins (TEB) and Karun River remains mostly unknown. To unravel their evolutionary history, we integrated the biogeography and climatic niche models of the freshwater fish with the largest natural distribution pattern. We investigated 16 species of the Barbinae subfamily with wide distributions and high diversity. Mitochondrial Cytb and COI genes were obtained from various locations via GenBank and utilized to generate a dated phylogeny and reconstructed ancestral areas with the BioGeoBEARS model. We used the BAMM tools to estimate rates of diversification through time. By integrating potential geographic distribution with 4 spatial climate variables, including maximum temperature of warmest month, minimum temperature of coldest month, temperature annual range, and annual precipitation, we reconstructed ancestral predicted niche occupancy (PNO) profiles using ecological niche modelling (ENM) method. Based on the evolution of endemic TEB and Karun River Barbinae, we hypothesized that ancestral clades appeared in the TEB in the late Oligocene/early Miocene (ca. 23.12 Mya) and dispersed to the basin from the mid-Miocene onward (ca. 14.33 Mya). Our results suggest that the mid-Miocene uplift of the Zagros Mountains likely impacted Karun River flow in southwestern Iran, contributing to the observed diversification patterns in Barbinae. In addition, niche divergence was dominant in Barbinae diversification, alongside phylogenetic niche conservatism. The study introduces a method combining phylogenetic, biogeographic, and niche modelling data to explore freshwater fish evolution in the Tigris-Euphrates and Karun basins, highlighting geological impacts on biodiversity and diversification processes.

Earthworms play a crucial role in the invertebrate community of soil by contributing to the belowground biomass and biogeochemical cycle. Environmental stresses, such as human activities and land use changes, have been found to negatively affect their abundance and diversity. To investigate the impact of agricultural land use and pastures on earthworms' genetic diversity in the Northern Zagros Mountains, we used COI molecular marker and DNA barcoding approaches. We collected earthworm specimens from four farmland sites and six pastures and assessed the abundance and species composition of earthworm communities across the two land uses using quadrat sampling. Using the barcoding method, we identified 13 molecular operational taxonomic units (MOTUs) among the captured earthworms. Our results showed that the number of total MOTUs, density, and earthworm communities differed significantly between the two land uses. We also found that pastures had more abundant earthworms, while farmlands had greater diversity. The diversity of OTUs in the Lumbricidae family was dominant in the agricultural system. Overall, the population of invasive earthworm species in cultivation systems is influenced by chemical inputs and organic materials from plant residues, cover crops, manure, or organic fertilizers. Given the rapid rate of land use change worldwide, especially in Iran, it is crucial to understand the impact of disturbances on earthworms.

Introduction: The Caspian Hyrcanian forests are a habitat with ancient growth of temperate broadleaf trees that spread along the Alborz Mountain range's northern slopes and near the southern borders of the Caspian Sea. However, human activities have significantly reduced forest cover, and identifying species diversity, forest structure, and human manipulations in Hyrcanian forests have received less attention. Macroinvertebrates are the main part of soil biodiversity in forests. Earthworms are one of the main components of soil biodiversity in forests and are one of the most valuable indicators of soil health and a vital component of soil fauna. Nevertheless, studying earthworms based on their morphological features poses various challenges. To overcome these challenges, DNA barcoding has emerged as a valuable tool extensively employed in biodiversity research. The study aims to use molecular approaches to identify earthworms and their diversity and compare the communities of these animals between natural and planted forests in the Hyrcanian region.Materials and Methods: The study was conducted in the central part of the Caspian Hyrcanian forests. The research was done in three locations, with two planted and two natural areas in each location. Within each area, a total of six quadrats were randomly placed to collect samples. Subsequently, the samples were classified based on their morphological characteristics. A total of 251 earthworm samples were collected, and 22 individuals were then selected for genetic studies using the cytochrome c oxidase subunit one (COI) gene after doing morphological sorting. The samples were initially kept in 96% ethanol for genetic studies to long-term storage. Univariate and multivariate statistical analyses were then performed to investigate the diversity of earthworms and compare their communities between planted and natural areas and three locations. Results: Based on genetic studies, 15 taxonomic units of earthworm were identified in the study area of the Hyrcanian forests. The research findings indicate that the abundance and total number of Operational Taxonomic Units (OTUs) in natural and planted areas are almost the same. The results of univariate statistical analysis (ANOVA) and multivariate analysis (PERMANOVA) did not show any significant difference for earthworms between natural and planted habitats.Discussion: The study demonstrates that the utilization of barcoding techniques yields more accurate results; however, the establishment of a comprehensive DNA reference library is necessary to enhance the precision of species classification. Despite finding no significant differences in earthworm communities between natural and planted forests, notable distinctions were detected among the three studied locations. This suggests that the dependence of earthworms on planted forests is contingent upon specific characteristics, soil conditions, and management practices. Moreover, the results show that earthworms are known for their ability to adapt to a wide range of environments. It is anticipated that secondary forests, which have been established for over two decades, will provide sufficient time for the restoration of earthworm populations, contributing to overall ecosystem recovery. The significance of this knowledge lies in its contribution to the sustainable preservation and effective administration of forests, particularly the Hyrcanian forests, which represent an ancient and invaluable ecosystem.

Mesalina watsonana is a species complex with a wide distribution range in Iran, some parts of Turkmenistan, Afghanistan, Pakistan, and northwest India. Recent molecular and morphological investigations detected remarkable hidden diversity among the geographical populations of the complex, more likely referring to the persistence of undescribed species. In this study, we conducted a very detailed sampling of localities and carried out a morphological study to investigate populations within the complex. Investigation of morphological features within the M. watsonana species complex indicated that it consists of seven distinct populations. They include the West-Southeast-South, East-Northeast, East Dasht-e Kavir, West Dasht-e Kavir, and two central groups (Halil and Kerman groups). Considering our findings, each of the seven populations corresponding to distinct geographic regions should be recognized as species. The six new species include Mesalina khuzestanensis sp. nov., Mesalina halilica sp. nov., Mesalina kermanensis sp. nov., Mesalina ardestanica sp. nov., Mesalina bardaskanensis sp. nov., Mesalina esfarayensis sp. nov. which are distinctive from each other due to their unique morphological characteristics.

The objective of this research was to assess the genetic diversity and phylogeography of Bombus terrestris and examine the historical events that shaped its contemporary genetic structures using the COI mitochondrial marker. Specimens of the species were collected from its distribution range alongside the Alborz Mountain range, and GenBank sequences from the Eurasian distribution range were incorporated into the dataset. The COI sequences were employed in Bayesian and Maximum Likelihood analyses to generate phylogenetic trees for the species populations and to investigate the evolutionary history of the species. Additionally, species occurrence points and climate data were utilized in Species Distribution Modeling (SDM) analyses to reconstruct the species range under past, present, and future climate conditions. The ML and BI trees yielded similar topologies, indicating extremely low genetic diversity and a homogeneous structure in the species population distribution range in Eurasia. Demographic analyses suggested that the species may have experienced a bottleneck during the last glacial maximum in Eurasia, followed by a recent expansion. The SDM analyses revealed significant fluctuations in the species range in the past and expansion under present conditions. Given the high dispersal ability of the species, the population expansion rate has surpassed the rate of developing new genetic diversity, and the estimated polymorphic sites for the species are likely relatively recent. This low level of genetic variation can also be attributed to the absence of geographical barriers and the excellent flying ability of the queen bee, leading to sustained gene flow throughout the entire continent. Despite the general correlation between larger populations and higher genetic diversity, bumblebees can expand their population size without increasing genetic diversity when residing in resourceful habitats.