Population Levels Research Articles

Momentary stress-induced food craving: An ecological momentary assessment study comparing perceived interpersonal and non-interpersonal stressors.

Daily-life stressors and food cravings are dynamic and vary within and across persons. Some evidence suggests interpersonal stressors increase appetite. However, little is known about the association of food craving with different types of stressors at the momentary level in the general population. We aimed to explore the momentary relationships between daily-life stressful events and food craving in a non-clinical community sample, and to compare the associations with food craving when the most stressful event was perceived as interpersonal versus non-interpersonal. We used ecological momentary assessment (EMA) to collect reports on the most stressful event, perceived stressor type, stressor appraisal, and food craving from 123 adults three times a day scheduled at fixed intervals over 10 days. Mixed effects random intercepts and slopes models examined the within- and between-person associations. Experiencing a stressor was significantly positively associated with within-person food craving at the same measurement. No differences in momentary food craving were found when the most stressful event was perceived as interpersonal or non-interpersonal (within-person level). However, frequently reporting the most stressful event as interpersonal (vs. non-interpersonal) was positively associated with food craving across the study (between-person level), particularly when the stressor was appraised as more unpleasant. Daily-life stressors were associated with momentary food craving. Individuals who generally perceived interpersonal stressors as their most stressful event tended to experience food cravings. Future research could further investigate the role of interpersonal stressors as a factor for overeating in daily life and the potential benefits of stress management in interventions.

Uncovering glacial footprints and identifying phylogeographic units in the freshwater crab Potamon elbursi Pretzmann, 1962 (Decapoda: Potamidae) based on mitochondrial data

The current patterns of biodiversity have significantly been affected by glacial-interglacial cycles during the Pleistocene period. True freshwater crabs are considered as poor dispersers and terrestrial barriers restrict gene flow between their local populations. Recent studies, however, suggest that certain environmental conditions, such as periods of heavy rainfall and humidity, can facilitate their between-drainage dispersal and will result in the evolution of homogenous genetic patterns among different drainage systems. Here we tested this hypothesis by comparing populations of the endemic freshwater crab Potamon elbursi Pretzmann, 1962 distributed in two drainage systems, the Caspian Sea and Namak Lake, in northern Iran. Our results based on the genetic analysis of 70 new and 61 previously published sequences of the mitochondrial cytochrome oxidase subunit I gene revealed a substantial haplotype diversity in some populations and high levels of local population structuring in others. Initially, we found mixed evidence of genetic differentiation and connectivity among drainages and populations. Genetic differentiation between the two drainages only became apparent after the Sepirdood population (which belongs to the Caspian Sea drainage) was excluded. Subsequently, the two drainages showed significant genetic distinctions, with a limited gene flow between them. Our demographic analyses supported recent population bottlenecks, followed by a rapid demographic and/or spatial expansion dating back to the Pleistocene climatic fluctuations. Species distribution modelling suggests that precipitation during warm weather conditions profoundly affects the distribution of P. elbursi. This study indicates that freshwater crabs can override short land barriers under favorable weather conditions and will have conservation implications in the face of contemporary climatic fluctuations.

A common multi-host parasite shows genetic structuring at the host species and population levels.

Although individual parasite species commonly infect many populations across physical space as well as multiple host species, the extent to which parasites traverse physical and phylogenetic distances is unclear. Population genetic analyses of parasite populations can reveal how parasites move across space or between host species, including helping assess whether a parasite is more likely to infect a different host species in the same location or the same host species in a different location. Identifying these transmission barriers could be exploited for effective disease control. Here, we analysed population genetic structuring of the parasite Pasteuria ramosa in daphniid host species from different lakes. Outbreaks occurred most often in the common host species Daphnia dentifera and Daphnia retrocurva. The genetic distance between parasite samples tended to be smaller when samples were collected from the same lake, the same host species and closer in time. Within lakes, the parasite showed structure by host species and sampling date; within a host species, the parasite showed structure by lake and sampling date. However, despite this structuring, we found the same parasite genotype infecting closely related host species, and we sometimes found the same genotype in nearby lakes. Thus, P. ramosa experiences challenges infecting different host species and moving between populations, but doing so is possible. In addition, the structuring by sampling date indicates potential adaptation to or coevolution with host populations and supports prior findings that parasite population structure is dynamic during outbreaks.

Systematic review of tobacco smoking prevalence among young people in treatment for first-episode psychosis.

To determine whether smoking prevalence in first-episode psychosis (FEP) is different than in people with established psychosis in long-term treatment. A systematic review of cross-sectional, case-control and cohort studies identified from searches of PubMed, Embase, CINAHL and PsycINFO up to 12 August 2023. 20 studies out of 2773 screened titles were included. There was no clear pattern of smoking by diagnosis as smoking rates in people with FEP ranged from 43% to 78%, while in those with established psychosis, it ranged from 19% to 76%. The wide range of smoking levels in both populations precluded conclusions as to whether smoking rates are different between people with FEP and established psychosis suggesting that factors other than the time course of the illness influence smoking levels.

Residue levels, processing factors and risk assessment of pesticides in ginger from market to table

Ginger is consumed as a spice and medicine globally. However, pesticide residues in ginger and their residue changes during processing remain poorly understood. Our results demonstrate that clothianidin, carbendazim and imidacloprid were the top detected pesticides in 152 ginger samples with detection rates of 17.11–27.63%, and these pesticides had higher average residues of 44.07–97.63 μg/kg. Although most samples contained low levels of pesticides, 66.45% of the samples were detected with pesticides, and 38.82% were contaminated with 2–5 pesticides. Peeling, washing, boiling and pickling removed different amounts of pesticides from ginger (processing factor range: 0.06–1.56, most <1). By contrast, pesticide residues were concentrated by stir-frying and drying (0.50–6.45, most >1). Pesticide residues were influenced by pesticide physico-chemical parameters involving molecular weight, melting point, degradation point and octanol–water partition coefficient by different ginger processing methods. Chronic and acute dietary risk assessments suggest that dietary exposure to pesticides from ginger consumption was within acceptable levels for the general population. This study sheds light on pesticide residues in ginger from market to processing and is of theoretical and practical value for ensuring ginger quality and safety.

Exercise-Mediated Protection against Air Pollution-Induced Immune Damage: Mechanisms, Challenges, and Future Directions.

Air pollution, a serious risk factor for human health, can lead to immune damage and various diseases. Long-term exposure to air pollutants can trigger oxidative stress and inflammatory responses (the main sources of immune impairment) in the body. Exercise has been shown to modulate anti-inflammatory and antioxidant statuses, enhance immune cell activity, as well as protect against immune damage caused by air pollution. However, the underlying mechanisms involved in the protective effects of exercise on pollutant-induced damage and the safe threshold for exercise in polluted environments remain elusive. In contrast to the extensive research on the pathogenesis of air pollution and the preventive role of exercise in enhancing fitness, investigations into exercise resistance to injury caused by air pollution are still in their infancy. In this review, we analyze evidence from humans, animals, and cell experiments on the combined effects of exercise and air pollution on immune health outcomes, with an emphasis on oxidative stress, inflammatory responses, and immune cells. We also propose possible mechanisms and directions for future research on exercise resistance to pollutant-induced damage in the body. Furthermore, we suggest strengthening epidemiological studies at different population levels and investigations on immune cells to guide how to determine the safety thresholds for exercise in polluted environments.

Spatial distribution pattern of male adults of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in lemon orchards in Northern Portugal

AbstractPhyllocnistis citrella Stainton, commonly known as the citrus leafminer, threatens global citrus production. This study focuses on elucidating the population dynamics and spatial distribution of P. citrella in lemon orchards located in Northern Portugal. From May to December, using delta traps with sexual pheromones, the levels of the adult population were monitored, and aggregation indices were calculated. Five distinct density peaks are observed, with the highest recorded in late July to early August. Spatial distribution consistently indicated an aggregated pattern. However, temporal variation in distribution was observed on specific dates. According to our results, it is suggested deploying two or three traps per hectare during peak density periods. This study significantly advances our understanding of P. citrella dynamics, emphasizing the need to consider spatial and temporal patterns for effective pest management. The outcomes underscore the importance of further exploration into factors influencing distribution patterns to refine control strategies. These insights are crucial for devising targeted and efficient measures to mitigate the impact of P. citrella on citrus orchards globally.

Flowering Ocimum gratissimum intercropped in tea plantations attracts and reduces Apolygus lucorum populations.

Apolygus lucorum is one of the most important piercing-sucking insect pests of the tea plant In this study, we assessed the attractiveness of basil plants to A. lucorum and the effectiveness of Ocimum gratissimum L. in the control of A. lucorum. The control efficiency of main volatile chemicals emitted from O. gratissimum flowers was also evaluated. Among seven basil varieties, O. gratissimum was more attractive to A. lucorum adults and was selected as a trap plant to assess its attractiveness to A. lucorum and effects on natural enemies in tea plantations. The population density of A. lucorum on trap strips of O. gratissimum in tea plantations was significantly higher than that on tea at 10-20 m away from the trap strips. Intercropping O. gratissimum with tea plants, at high-density significantly reduced A. lucorum population levels. Eucalyptol, limonene, β-ocimene, and linalool were the four dominant components in the O. gratissimum flower volatiles, and their emissions showed a gradual upward trend over the sampling period. Olfactometer assays indicated that eucalyptol and dodecane showed attraction to A. lucorum. High numbers of A. lucorum were recorded on limonene, eucalyptol, and myrcene-baited yellow sticky traps in field trials in which 11 dominant volatiles emitted by O. gratissimum flowers were evaluated. Our research indicated that the aromatic plant O. gratissimum and its volatiles could attract A. lucorum and planting O. gratissimum has the potential as a pest biocontrol method to manipulate A. lucorum populations in tea plantations. © 2024 Society of Chemical Industry.

‘Dead birds flying': can north American rehabilitated raptors released into the wild mitigate anthropogenic mortality?

As the human footprint expands to meet societal energy needs, as do the impacts to wildlife. Raptors in particular are highly susceptible to anthropogenic caused mortality. Industry sectors are encouraged to offset these causes of mortality. Several options to mitigate these losses have been proposed, including raptor rehabilitation. However, its role as a conservation tool is untested. Currently no peer‐reviewed demographic analyses exist using post‐release data from rehabilitated raptors to evaluate its effectiveness at continental scales. Our objectives were to estimate annual survival of rehabilitated and wild raptors, and then use those estimates in demographic models to assess potential effects at individual and population levels. We hypothesized that rehabilitated raptors would survive similarly to their wild counterparts after an acclimation period, and that longer‐lived species (K‐selected) would benefit most from these releases. We used US Geological Survey Bird Banding Lab band‐recovery data (1974–2018) from 20 raptor species for modeling survival of rehabilitated individuals (n = 125 740) in comparison to wild birds (n = 1 913 352). Results from 17 species with adequate recovery data indicated that five species rehabilitated ≠ wild survival, two species had uncertain estimates, and 10 species rehabilitated ≈ wild survival by years two and three post‐release. We acquired admission (n = 69 707) and release (n = 25 740) data from 24 rehabilitation centers across the US (2012–2021). We integrated survival, fecundity and numbers of releases into demographic models. These models quantified the extent to which rehabilitated raptors may contribute to broader conservation efforts, especially in the context of individual take. All but two species, had measurable numbers of individuals added to the population regardless of the number of releases. The general pattern was for K‐selected species to yield larger benefits from rehabilitated supplementation to the population. These results provide evidence that rehabilitation may serve as mitigation tool to offset incidental take.

Cadmium inhibits calcium activity in hippocampal CA1 neurons of freely moving mice.

Cadmium (Cd) is a ubiquitous toxic heavy metal and a potential neurotoxicant due to its wide use in industrial manufacturing processes and commercial products, including fertilizers. The general population is exposed to Cd through food and smoking due to high transfer rates of Cd from contaminated soil. Cd has been shown to mimic calcium ions (Ca2+) and interfere with intracellular Ca2+ levels and Ca2+ signaling in in vitro studies. However, nothing is known about Cd's effects on Ca2+ activity in neurons in live animals. This study aimed to determine if Cd disrupts Ca2+ transients of neurons in CA1 region of the hippocampus during an associative learning paradigm. We utilized in vivo Ca2+ imaging in awake, freely moving C57BL/6 mice to measure Ca2+ activity in CA1 excitatory neurons expressing genetically encoded Ca2+ sensor GCaMP6 during an associative learning paradigm. We found that a smaller proportion of neurons are activated in Cd-treated groups compared to control during fear conditioning, suggesting that Cd may contribute to learning and memory deficit by reducing activity of neurons. We observed these effects at Cd exposure levels that result in blood Cd levels comparable to the general US population levels. This provides a possible molecular mechanism for Cd interference of learning and memory at exposure levels relevant to US adults. To our knowledge, our study is the first to describe Cd effects on brain Ca2+ activity in vivo in freely behaving mice.

Vitamin D Deficiency in Patients With Low-Energy Hip Fractures in Accordance With the Mediterranean Paradox.

Introduction Vitamin D deficiency (VDD) is considered one of the leading causes of poor bone quality. It may also be related to severe muscular weakness, especially in the elderly, which leads to frequent falls. Thus, VDD might be associated with fragility fractures of the hip, wrist, and spine in this age category.In this cross-sectional study, our goal was to present vitamin D levels in an elderly Mediterranean population with hip fractures and to assess whether its levels are related to the incidence or prevention of such injuries. Methods Between January and December 2021, 140 patients aged 65 years or older were hospitalized in our department with a fracture involving the hip joint. Serum calcium and vitamin D level control was performed upon admission, as well as recording whether anti-osteoporosis medication had been prescribed. Only patients with low-energy fractures were included, whereas oncologic patients and those with high-energy trauma were excluded. Results Thirty-eight men and 102 women, with a mean age of 83.12 and 84.88 years, respectively, participated in our study. Intertrochanteric fractures were the most common injuries (50.72%). Low vitamin D levels (<30 ng/mL) were observed in 132 patients (94.28%). A bone density scan during the last year had been conducted by only seven patients (5%), whereas in 136patients (97.14%), no anti-osteoporotic medication was given. Conclusion There is an excessive percentage of aged patients with hip fractures in Greece, demonstrating a significant vitamin D insufficiency despite the high annual frequency of sunny days in this Mediterranean region. Presumably, most of these patients neither perform the routine bone density scan nor do they take any kind of preventive pharmaceutical treatment, which might reveal devaluation of osteoporosis from this age group due to contingent comorbidities.

A One-Year Retrospective Study for the Evaluation of Correlation between Vitamin D and Cholesterol Levels: A Preliminary Report

Vitamin D is a fat-soluble vitamin that plays an important role in bone metabolism and seems to have some anti-inflammatory and immune-modulating properties. Cholesterol is the precursor of very important biochemical pathways including bile salts and other steroidogenic molecules like adrenal gland hormones, reproductive hormones, and vitamin D. In the present study, cholesterol and vitamin D test results from 13,150 patients admitted to our laboratory were analyzed over a one-year period retrospectively from the Laboratory Information System. In our study, we aimed to investigate the association between low cholesterol levels and vitamin D levels. Analyzed data revealed that low cholesterol levels (&lt;200 mg/dl) were detected in 6,355 patients. In these patients, mean cholesterol level was 164.3 mg/dl while median vitamin D value was 20.4 ng/ml. There was a significant correlation (r=0.064, p&lt;0.001) between low cholesterol levels and low vitamin D levels in the study group. The study group was divided into three subgroups according to age (&lt;18, 18-35 and &gt;35) and a significant correlation was detected between low cholesterol levels and low vitamin D (r=0.06, p&lt;0.001) in patients &gt;35 years of age. In this retrospective study, we determined a weak but significant correlation between vitamin D and cholesterol levels in particular &gt;35 years of age. We think that this study data can be considered as a preliminary report for comprehensive studies that will determine the relationship between vitamin D and cholesterol levels in the general population.

Relevance of population mobility for climate change mitigation

Population mobility and immobility are depicted prominently in the climate change adaptation literature either as maladaptation, or failure to adapt, or as a key strategy for adaptation in place or elsewhere. On the other hand, the relevance of population mobility in the context of climate change mitigation has not been highlighted to the same extent as, for example, population growth and fertility. And yet, as the outcomes of people moving around – sometimes in unexpected ways because of local combinations of policies, contexts and shocks – population mobility patterns, trends and levels could both facilitate and constrain climate change mitigation efforts. In this brief note, I suggest that climate change mitigation strategies and actions need to take into account their potential interactions with population mobility because it is a key component of population growth, population distribution and urbanisation trends, as well as a potential contributor to behavioural change.

Trabecular bone volume fraction in Holocene and Late Pleistocene humans

Research suggests that recent modern humans have gracile skeletons in having low trabecular bone volume fraction (BV/TV) and that gracilization of the skeleton occurred in the last 10,000 years. This has been attributed to a reduction in physical activity in the Holocene. However, there has been no thorough sampling of BV/TV in Pleistocene humans due to limited access to high resolution images of fossil specimens. Therefore, our study investigates the gracilization of BV/TV in Late Pleistocene humans and recent (Holocene) modern humans to improve our understanding of the emergence of gracility. We used microcomputed tomography to measure BV/TV in the femora, humeri and metacarpals of a sample of Late Pleistocene humans from Dolní Věstonice (Czech Republic, ∼26 ka, n = 6) and Ohalo II (Israel, ∼19 ka, n = 1), and a sample of recent humans including farming groups (n = 39) and hunter-gatherers (n = 6). We predicted that 1) Late Pleistocene humans would exhibit greater femoral and humeral head BV/TV compared with recent humans and 2) among recent humans, metacarpal head BV/TV would be greater in hunter-gatherers compared with farmers. Late Pleistocene humans had higher BV/TV compared with recent humans in both the femur and humerus, supporting our first prediction, and consistent with previous findings that Late Pleistocene humans are robust as compared to recent humans. However, among recent humans, there was no significant difference in BV/TV in the metacarpals between the two subsistence groups. The results highlight the similarity in BV/TV in the hand of two human groups from different geographic locales and subsistence patterns and raise questions about assumptions of activity levels in archaeological populations and their relationships to trabecular BV/TV.

Morphological variations and demographic responses of the Mediterranean pond turtle Mauremys leprosa to heterogeneous aquatic habitats

Human activities affect terrestrial and aquatic habitats leading to changes at both individual and population levels in wild animal species. In this study, we investigated the phenotype and demographics of the Mediterranean pond turtle Mauremys leprosa (Schweigger, 1812) in contrasted environments of Southern France: two peri-urban rivers receiving effluents from wastewater treatment plants (WWTP), and another one without sewage treatment plant. Our findings revealed the presence of pesticides and pharmaceuticals in the three rivers of investigation, the highest diversities and concentrations of pollutants being found in the river subsections impacted by WWTP effluents. Principal component analysis and hierarchical clustering identified three levels of habitat quality, with different pollutant concentrations, thermal conditions, nutrient, and organic matter levels. The highest turtle densities, growth rates, and body sizes were estimated in the most disturbed habitats, suggesting potential adult benefits derived from harsh environmental conditions induced by pollution and eutrophication. Conversely, juveniles were the most abundant in the least polluted habitats, suggesting adverse effects of pollution on juvenile survival or adult reproduction. This study suggests that turtles living in polluted habitats may benefit from enhanced growth and body size, at the expense of reproductive success.

Genetic determinants of plasma protein levels in the Estonian population

The proteome holds great potential as an intermediate layer between the genome and phenome. Previous protein quantitative trait locus studies have focused mainly on describing the effects of common genetic variations on the proteome. Here, we assessed the impact of the common and rare genetic variations as well as the copy number variants (CNVs) on 326 plasma proteins measured in up to 500 individuals. We identified 184 cis and 94 trans signals for 157 protein traits, which were further fine-mapped to credible sets for 101 cis and 87 trans signals for 151 proteins. Rare genetic variation contributed to the levels of 7 proteins, with 5 cis and 14 trans associations. CNVs were associated with the levels of 11 proteins (7 cis and 5 trans), examples including a 3q12.1 deletion acting as a hub for multiple trans associations; and a CNV overlapping NAIP, a sensor component of the NAIP-NLRC4 inflammasome which is affecting pro-inflammatory cytokine interleukin 18 levels. In summary, this work presents a comprehensive resource of genetic variation affecting the plasma protein levels and provides the interpretation of identified effects.

Early-Life Lead Exposure: Risks and Neurotoxic Consequences.

Lead (Pb) does not have any biological function in a human, and it is likely no safe level of Pb in the human body. The Pb exposure impacts are a global concern for their potential neurotoxic consequences. Despite decreasing both the environmental Pb levels and the average blood Pb levels in the survey populations, the lifetime redistribution from the tissues-stored Pb still poses neurotoxic risks from the low-level exposure in later life. The growing fetus and children hold their innate high-susceptible to these Pb-induced neurodevelopmental and neurobehavioral effects. This article aims to evaluate cumulative studies and insights on the topic of Pb neurotoxicology while assessing the emerging trends in the field. The Pb-induced neurochemical and neuro-immunological mechanisms are likely responsible for the high-level Pb exposure with the neurodevelopmental and neurobehavioral impacts at the initial stages. Early-life Pb exposure can still produce neurodegenerative consequences in later life due to the altered epigenetic imprints and the ongoing endogenous Pb exposure. Several mechanisms contribute to the Pb-induced neurotoxic impacts, including the direct neurochemical effects, the induction of oxidative stress and inflammation through immunologic activations, and epigenetic alterations. Furthermore, the individual nutritional status, such as macro-, micro-, or antioxidant nutrients, can significantly influence the neurotoxic impacts even at low-level exposure to Pb. The prevention of early-life Pb exposure is, therefore, the critical determinant for alleviating various Pb-induced neurotoxic impacts across the different age groups.

Longitudinal associations between ambient PM2.5 exposure and lipid levels in two Indian cities.

Exposure to ambient PM2.5 is known to affect lipid metabolism through systemic inflammation and oxidative stress. Evidence from developing countries, such as India with high levels of ambient PM2.5 and distinct lipid profiles, is sparse. Longitudinal nonlinear mixed-effects analysis was conducted on >10,000 participants of Centre for cArdiometabolic Risk Reduction in South Asia (CARRS) cohort in Chennai and Delhi, India. We examined associations between 1-month and 1-year average ambient PM2.5 exposure derived from the spatiotemporal model and lipid levels (total cholesterol [TC], triglycerides [TRIG], high-density lipoprotein cholesterol [HDL-C], and low-density lipoprotein cholesterol [LDL-C]) measured longitudinally, adjusting for residential and neighborhood-level confounders. The mean annual exposure in Chennai and Delhi was 40 and 102 μg/m3 respectively. Elevated ambient PM2.5 levels were associated with an increase in LDL-C and TC at levels up to 100 µg/m3 in both cities and beyond 125 µg/m3 in Delhi. TRIG levels in Chennai increased until 40 µg/m3 for both short- and long-term exposures, then stabilized or declined, while in Delhi, there was a consistent rise with increasing annual exposures. HDL-C showed an increase in both cities against monthly average exposure. HDL-C decreased slightly in Chennai with an increase in long-term exposure, whereas it decreased beyond 130 µg/m3 in Delhi. These findings demonstrate diverse associations between a wide range of ambient PM2.5 and lipid levels in an understudied South Asian population. Further research is needed to establish causality and develop targeted interventions to mitigate the impact of air pollution on lipid metabolism and cardiovascular health.

Large multi-decade beaver ponding changes in the subarctic Hudson Bay Lowlands, Canada observed using satellite remote sensing

Beavers strongly impact hydrology and ecosystems through their widespread dam building that creates ponds and wetlands. Monitoring the relative abundance of beavers and their waterbodies is needed to assess these effects and factors influencing population levels. However, the ability to do this over vast, remote regions is limited with conventional aerial or field-based surveying. To address this challenge, we developed a satellite remote sensing method to track beaver ponding changes over multiple decades and applied it to a 5127 km2 region of the coastal Hudson Bay Lowlands in Manitoba, Canada. Annual, sub-pixel surface water mapping using 30 m resolution Landsat satellite data, combined with a spatial database of beaver dams, permitted the mapping of 37 year (1985–2021) beaver ponding dynamics. We identified 1714 beaver dams and 1085 beaver pond complexes covering 31 km2, indicating that beavers have an important influence on stream hydrology in this high subarctic landscape. The total area of ponding decreased by 53% from 1986–1989 and by 80% by 1995, and then gradually recovered to initial levels by 2015. The early, steep drop in beaver ponding corresponded to a 13% decline in regional surface water area, while a similar wetness decline during 2015–2018 resulted in little change in beaver ponding. We suggest that strong beaver ponding dynamics were likely caused by the interaction between streamflow levels and beaver populations living near their northern range limit and cold tolerance. The pond mapping method can be applied to other regions if the long-term distribution of beaver dams is known, and ponds are large enough to be identified using a Landsat sub-pixel approach.

Gravity Models for Global Migration Flows: A Predictive Evaluation

This study introduces a comprehensive econometric framework based on gravity equations and designed to forecast migrant flows between countries. The model’s theoretical underpinnings are validated through empirical data, and we show that the model has better out-of-sample predictive ability than alternative global models. We explore the quantitative effects of various socioeconomic, demographic, and geographic factors on migration and illustrate its use to obtain scenario-driven projections of bilateral migration, assessing the potential contributions of migration to population and GDP dynamics in Germany and Portugal for the period 2021–2025. Our projection results highlight the critical role of immigration in sustaining population levels and economic growth, particularly in the context of ageing populations and decreasing fertility rates across Europe.