Dispersal Patterns Research Articles

Apex predators can structure ecosystems through trophic cascades: Linking the frugivorous behaviour and seed dispersal patterns of mesocarnivores

Abstract Current global change scenarios demand knowledge on how anthropogenic impacts affect ecosystem functioning through changes in food web structure. Frugivorous mesocarnivores are a key link in trophic cascades because, while their abundance and behaviour are usually controlled by apex predators, they can provide high‐quality seed‐dispersal services to plant communities. Thus, the recent rewilding of large carnivores worldwide can trigger cascading effects for plants. We investigated the top‐down effects of an apex predator (Iberian lynx Lynx pardinus) on seed‐dispersal services mediated by two mesocarnivore species (red fox Vulpes vulpes and stone marten Martes foina) at the plant community level by comparing areas with and without lynx in a Mediterranean mountain range in Southern Spain. We collected scats of mesocarnivores (n = 1575) to assess frugivory and seed dispersal of 15 plant species over two consecutive fruiting seasons and two habitat types (open and forest). Specifically, we assessed the effect of lynx presence on (i) seed occurrence and fleshy‐fruit biomass per scat, (ii) number of scats containing seeds and (iii) diversity of dispersed seeds. The quantity and diversity of dispersed seeds drastically decreased under predation risk for both mesocarnivore's species. Seed dispersal by stone martens was negatively affected by the presence of lynx, with a marked reduction in the number of scats with seeds (93%) and the diversity of dispersed seeds (46%). Foxes dispersed 68% fewer seeds in open habitats when coexisting with lynx, probably leading to differential contributions to seed‐dispersal effectiveness among habitats. Our study reveals a novel trophic cascade from apex predators to plant communities. The behavioural responses of frugivorous mesocarnivores to predation risk and the reduction in the intensity of their faecal deposition pattern are probably related to their lower abundance when co‐occurring with apex predators. While rewilding apex predators is a successful conservation tool, attention should be paid to cascading effects across food webs, particularly where frugivore megafauna is missing and mesocarnivores provide unique services to plants. Read the free Plain Language Summary for this article on the Journal blog.

Integrating Unsupervised and Supervised ML Models for Analysis of Synthetic Data From VAE, GAN, and Clustering of Variables

Clustering of variables is a specialized approach for dimensionality reduction. This strategy is evaluated for data reduction with a Kaggle diabetes dataset. Since the original dataset is small, Generative Adversarial Networks (GAN) and Variational Autoencoders (VAE) are used to generate 100,000 records and tested for resemblance to the real data using standard statistical methods. VAE-data is more representative of the real data than GAN-data when analyzed using machine learning (ML) models. Applying Clustering of Variables on VAE-data yields new synthetic variables (SV). SV-data is then augmented with target variable data. Random Forest model is used on VAE and SV data. SV-data results matched VAE-data, proving the new data's quality. SV-data also provides insights into correlations and data dispersion patterns. This analysis implements a combination of Unsupervised learning (clustering of variables) and Supervised learning (classification) which is reflected in the results.

Surface Deformation Monitoring and Subsidence Mechanism Analysis in Beijing based on Time-series InSAR

Abstract. This article uses 43 Sentinel-1A image datasets covering Beijing to obtain time series surface deformation information in the study area from January 2022 to October 2023. It analyzes the causes of land subsidence by integrating precipitation and urban construction. The main research results are as follows: (1) Three distinct subsidence areas are identified in the eastern part of Chaoyang District in Beijing (Subsidence Area A), the northwestern part of Tongzhou District in Beijing (Subsidence Area B), and Yanjiao Town in Hebei Province (Subsidence Area B), which is adjacent to Beijing. Subsidence Areas A and B exhibit a dispersed pattern, with maximum land subsidence rates exceeding −30 mm/year. In contrast, Subsidence Areas C displays a funnel-shaped subsidence, where the majority of areas experience land subsidence rates exceeding −25 mm/year, with a maximum rate reaching −45 mm/year. (2) Precipitation has a significant impact on surface deformation in the study area, and there is a strong correlation between precipitation and land subsidence, with correlation values of 0.77, 0.77, and 0.74, respectively. (3) Urban construction has a certain impact on land subsidence, but the degree of impact varies in different regions.

Geospatial Assessment of Urban Sprawl: A Case Study of Herat City, Afghanistan

This study aims to investigate the spatial and temporal dynamics of urban sprawl in Herat City, Afghanistan, from 2000 to 2021 using GIS and remote sensing data (Landsat 7 and 8). In this study, three machine learning algorithms, namely Support Vector Machine (SVM), Random Forest (RF), and Classification and Regression Trees (CART), were employed to classify the study area, and the accuracy of each algorithm for each study period was assessed. Based on the assessment results, the RF algorithm demonstrated higher accuracy and was selected as the classification algorithm. The Google Earth Engine cloud platform was utilized to classify the study area, and the GIS environment was employed for the creation of thematic layers. The analysis revealed a 30.06% increase in built-up areas from 2000 to 2021. Conversely, vegetation, water bodies, and bare land decreased by 8.51%, 1.08%, and 20.53%, respectively, during the same period. The findings indicated that Herat City experienced high-speed expansion between 2000 and 2013, while from 2013 to 2021; it developed at a medium speed. The Relative Shannon's entropy statistical algorithm was employed to quantify urban sprawl, and the results suggest a dispersed urban sprawl pattern. Internal migration to major cities due to conflicts, limited employment opportunities, and inadequate living amenities in rural areas has been a primary driver of urban sprawl in Herat City, Afghanistan.

Northward expansion of the West Kunlun orogenic belt during the Cenozoic and its implications for the evolution of the northwest Tibetan Plateau: Constraints from sediment dispersal patterns in the Buya Basin, China

The West Kunlun orogenic belt, which defines the northwestern margin of the Tibetan Plateau, holds important information on plateau growth. Despite its significance, views about its uplift history continues to be under debate, with two competing hypotheses involving episodic uplift or northward expansion, related to a fixed or movable plateau boundary, respectively. The Buya Basin, a small basin located between the North and South Kunlun terranes, is key to understanding the Cenozoic uplift history of the West Kunlun orogenic belt. In this study, we conducted sedimentary and detrital zircon UPb geochronological analyses on the Cenozoic sediments of the Buya Basin. According to the findings of the sedimentary investigation, the Cenozoic strata of the basin generally show gradual changes from low- to high-energy deposition interrupted by a reverse trend in the Anjuan Formation. Moreover, the detrital zircon UPb geochronological results indicate that the Buya Basin received sediments initially from the Songpan–Ganzi and South Kunlun terranes during the deposition of the Keziluoyi to Pakabulake formations and then from the South and North Kunlun terranes during the deposition of the Artux Formation. This change in sediment dispersal patterns demonstrates that the uplift of the West Kunlun orogenic belt has expanded northwards to the North Kunlun terrane, which suggests that the northwestern boundary of the Tibetan Plateau has been a northward-moving feature in the context of India–Eurasia convergence. Along with previous studies, we suggest that the northward expansion of the northwest Tibetan Plateau is accommodated by decoupling deformation along the southern Tarim Basin, with northward thrusting of the foreland fold-and-thrust belts in the upper crust and southward underthrusting in the lower plate.

Precipitation patterns and their variability in the southern region of Brazil

Climate change is a long-term transformation of climate patterns, which can be natural or anthropogenic. Signs of climate change can manifest themselves in different ways: through the occurrence of extreme events, rising ocean levels, melting glaciers, among others. Negative impacts are produced by climate change and are one of humanity's biggest concerns, since its effects reach the entire planet with different consequences. Considering the need for actions aimed at contributing to the process of mitigating climate change, the importance of knowing changes in regional climate patterns is emphasized. This study aims to analyze changes in precipitation patterns over time in the southern region of Brazil, including variability, trends, anomalies, droughts and excess rainfall. Daily precipitation data from 1961 to 2020 were used, collected at 15 meteorological stations in the region. Various statistical analyzes were carried out, such as averages, maximum and minimum values, seasonal and annual anomalies, frequency distribution, Mann-Kendall trend tests and the Normalized Precipitation Index (SPI). The results indicate that climate change trends are positive in terms of increasing rainfall volumes, altering rainfall dispersion patterns (volume). In other words, rainfall is more irregular in terms of distribution throughout the seasons. The big highlight was Florianópolis -SC, which during the summer had the highest volume of rain among the meteorological stations studied.

“We Cannot Go There, They Cannot Come Here”: Dispersed Care, Asian Indian Immigrant Families and the COVID-19 Pandemic

“We Cannot Go There, They Cannot Come Here”: Dispersed Care, Asian Indian Immigrant Families and the COVID-19 Pandemic

Improved multiscale coded dispersion entropy: A novel quadratic-coded health indicator of rolling bearings

Abstract Dispersion entropy (DE) is widely used to quantify the complexity of nonlinear time series. In order to improve the ability to capture fault characteristics, a novel approach called coded dispersion entropy (CDE) has been introduced in recent years. CDE aims to expand the number of possible dispersion patterns and enhance the encoding of similar dispersion patterns. However, the coding method of CDE ignores the amplitude differences between dispersion elements and average elements, resulting in the inaccurate assignment of samples. Additionally, CDE is unable to extract effective information from other time scales. These limitations hinder the ability of CDE to effectively characterize faults. This paper proposes an improved multiscale coded dispersion entropy (IMCDE) to solve these limitations. The method introduces the interval scaling factor "R" and utilizes the sum and difference between the mean element and R as new coding boundaries. This approach addresses the sensitivity issue of the CDE coding mode towards smaller amplitude differences by the reasonable quadratic coding mode. Additionally, a composite coarse-graining process is introduced to rearrange the first coarse-grained point in sequence, resulting in multiple sets of sequences. The average probability of the same dispersion pattern at each scale is calculated to correct the entropy error. The experimental results from two sets of bearing faults demonstrate the effectiveness of this method in extracting critical features associated with faulty bearings. Furthermore, the method showed higher classification accuracy compared to multiscale dispersion entropy (MDE) and multiscale coded dispersion entropy (MCDE). Additionally, it exhibited smaller classification error than MDE and MCDE.

The functional diversity-productivity relationship of woody plants is climatically sensitive.

Plot-scale experiments indicate that functional diversity (FD) plays a pivotal role in sustaining ecosystem functions such as net primary productivity (NPP). However, the relationships between functional diversity and NPP across larger scale under varying climatic conditions are sparsely studied, despite its significance for understanding forest-atmosphere interactions and informing policy development. Hence, we examine the relationships of community-weighted mean (CWM) and functional dispersion (FDis) of woody plant traits on NPP across China and if such relationships are modulated by climatic conditions at the national scale. Using comprehensive datasets of distribution, functional traits, and productivity for 9120 Chinese woody plant species, we evaluated the distribution pattern of community-weighted mean and functional dispersion (including three orthogonal trait indicators: plant size, leaf morphology, and flower duration) and its relationships with NPP. Finally, we tested the effects of climatic conditions on community-weighted mean/functional dispersion-NPP relationships. We first found overall functional diversity-NPP relationships, but also that the magnitude of these relationships was sensitive to climate, with plant size community-weighted mean promoting NPP in warm regions and plant size functional dispersion promoting NPP in wet regions. Second, warm and wet conditions indirectly increased NPP by its positive effects on community-weighted mean or functional dispersion, particularly through mean plant size and leaf morphology. Our study provides comprehensive evidence for the relationships between functional diversity and NPP under varying climates at a large scale. Importantly, our results indicate a broadening significance of multidimensional plant functional traits for woody vegetation NPP in response to rising temperatures and wetter climates. Restoration, reforestation actions and natural capital accounting need to carefully consider not only community-weighted mean and functional dispersion but also their interactions with climate, to predict how functional diversity may promote ecosystem functioning under future climatic conditions.

Dispersal and connectivity in increasingly extreme climatic conditions.

While climate change has been shown to impact several life-history traits of wild-living animal populations, little is known about its effects on dispersal and connectivity. Here, we capitalize on the highly variable flooding regime of the Okavango Delta to investigate the impacts of changing environmental conditions on the dispersal and connectivity of the endangered African wild dog (Lycaon pictus). Based on remote sensed flood extents observed over 20 years, we derive two extreme flood scenarios: a minimum and a maximum flood extent, representative of very dry and very wet environmental periods. These conditions are akin to those anticipated under increased climatic variability, as it is expected under climate change. Using a movement model parameterized with GPS data from dispersing individuals, we simulate 12,000 individual dispersal trajectories across the ecosystem under both scenarios and investigate patterns of connectivity. Across the entire ecosystem, surface water coverage during maximum flood extent reduces dispersal success (i.e., the propensity of individuals to disperse between adjacent subpopulations) by 12% and increases dispersal durations by 17%. Locally, however, dispersal success diminishes by as much as 78%. Depending on the flood extent, alternative dispersal corridors emerge, some of which in the immediate vicinity of human-dominated landscapes. Notably, under maximum flood extent, the number of dispersing trajectories moving into human-dominated landscapes decreases by 41% at the Okavango Delta's inflow, but increases by 126% at the Delta's distal end. This may drive the amplification of human-wildlife conflict. While predicting the impacts of climate change on environmental conditions on the ground remains challenging, our results highlight that environmental change may have significant consequences for dispersal patterns and connectivity, and ultimately, population viability. Acknowledging and anticipating such impacts will be key to effective conservation strategies and to preserve vital dispersal corridors in light of climate change and other human-related landscape alterations.

Impacts of habitat loss and fragmentation on seed dispersal by an Afrotropical bird community in an anthropogenic landscape: Insights from movement models

Habitat loss and fragmentation can affect seed dispersal by impacting seed dispersers' habitat choices, behavior, and movement patterns. Here we studied seed dispersal by an Afrotropical bird community in an anthropogenic landscape in Kenya. We used telemetry data of six bird species, estimated their habitat choices, behavior, and movement patterns in the forest fragments and the matrix. We then integrated our model estimates into a seed dispersal simulation model with multiple artificial anthropogenic landscapes, experiencing different levels of habitat loss and fragmentation. In our simulations, we included two seed disperser groups: forest specialist and habitat generalist birds that moved in the landscape using a mixture-correlated random walk, and encamped and traveled in the different habitat types. Increased habitat loss diminished seed dispersal distances, where seeds carried by forest specialist dispersers suffered a stronger reduction in dispersal distances compared to habitat generalists, and number of seeds deposited in habitat fragments, where fewer seeds were deposited into the fragments by habitat generalist dispersers compared to forest specialists. The effects of habitat fragmentation were similar to but weaker than that of habitat loss, and most apparent at an intermediate level of habitat loss. Other seed dispersal metrics, including spatial extent of seed rain and nearest neighbor distances among seeds, did not show any strong relationships with either habitat loss or fragmentation. Therefore, movement models offer valuable perspectives on how habitat loss and fragmentation can influence seed dispersal patterns, by reliably estimating habitat choices, behavior, and movement patterns of dispersers, and potentially benefiting efforts to conserve this ecological interaction.

Investigation of Air Quality for Malegaon Region

Abstract: The purpose of this study is to examine the quality of the air in the Malegaon region by identifying, quantifying, and evaluating contaminants and their effects on the environment and public health. The Malegaon region's air quality has been a rising topic of concern because of industrial operations, vehicle emissions, and other human-caused factors. elevated concentrations of many pollutants, including Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Particulate matter (PM2.5, PM10), and Ozone (O3).It's an intriguing problem to comprehend the mechanics of air pollution in a semi-urban location like Malegaon. The dispersion and concentration patterns of pollutants are influenced by various factors, including terrain, meteorological circumstances, and industrial expansion. The challenge is further complicated by evaluating the combined effects of several pollution sources on air quality. In order to thoroughly evaluate the state of the air in the Malegaon region, this study uses a multidisciplinary method that combines statistical analysis, atmospheric modeling, and air quality monitoring.

Factors influencing the variation of the Sepik-Ramu River system's sediment plume off the north coast of New Guinea

The Sepik-Ramu River system (SRRs) is a principal contributor of terrestrial materials to the pelagic waters of the tropical Western Pacific, boasting the highest sediment discharge in New Guinea. However, this system's sediment outflow and dispersal patterns are not well-documented. This study seeks to address this gap by analyzing the estuarine sediment plumes, which are the key indicators of the marine dispersion of terrestrial materials. Utilizing Moderate Resolution Imaging Spectroradiometer (MODIS) images from 2010 to 2020 and applying the Novoa17 algorithm, we examined the distribution and temporal evolution of the sediment plume of the SRRs estuary. The sediment plume was categorized into two distinct zones: core and diffuse, based on suspended sediment concentration (SSC) levels. Our findings reveal significant seasonal variations of these sediment plumes in the nearshore. The plume area expands during the wet season and contracts during the dry season, respectively, with core and diffuse plumes sharing similar change characteristics. The diffuse plume primarily extends northeast in the wet season and subsequently shifts northwest in the dry season, and the core plume consistently points to the northeast. The study further explores the driving factors and mechanisms behind these patterns, identifying river discharge as the primary influence on the core plume and sea surface winds and coastal currents as determinants of the diffuse plume's behavior. Interannual variations in the plume characteristics were found to be influenced by the El Niño-Southern Oscillation (ENSO), which indirectly affects plume dynamics through its impact on regional precipitation. During El Niño events, characterized by drier conditions and reduced discharge, the plume SSC and area typically decrease. During La Niña events, the plume's SSC and area typically increase, except for the 2011 super La Niña's negative anomaly, caused by the rain belt's excessive westward shift.

Characteristics and numerical simulation of chromium transportation, migration and transformation in soil–groundwater system

Understanding chromium (Cr) migration and dispersion patterns in the soil-groundwater system is critical for the control and remediation of subsurface Cr contamination. In this study, a typical Cr-contaminated site from the Pearl River Delta (PRD) in China was simulated with a three-dimensional (3D) sandbox experiment to investigate the migration and transformation behavior of Cr. Results revealed that under the combined influence of rainfall and groundwater flow, a complex flow field favorable for 3D migration and solute dispersion was formed. The flow field characteristics were influenced by water-table depth, which in turn affected Cr behavior in the system. Moreover, downward flow field expansion under low water-table conditions led to Cr vertical migration range expansion, causing greater contamination in the deep soil. The migration process was accompanied with Cr(VI) reduction, during which approximately 75 % of the total Cr was immobilized in soils. The reactive transport model achieved a good fit for Cr retention and morphological distribution in the solid phase. The model indicates that Cr is more readily transported and dispersed with groundwater, and Cr migrated and spread downstream by 15 m during the eighth year. Therefore, managing water-table depth could be a strategy to minimize the Cr vertical migration and contamination.

Effective dispersal patterns in prairie plant species across human-modified landscapes.

Effective dispersal among plant populations is dependent on vector behaviour, landscape features and availability of adequate habitats. To capture landscape feature effects on dispersal, studies must be conducted at scales reflecting single-generation dispersal events (mesoscale). Many studies are conducted at large scales where genetic differentiation is due to dispersal occurring over multiple generations, making it difficult to interpret the effects of specific landscape features on vector behaviour. Genetic structure at the mesoscale may be determined by ecological and evolutionary processes, such as the consequences of vector behaviour on patterns of gene flow. We used chloroplast haplotypes and nuclear genome SNP surveys to identify landscape features influencing seed and pollen dispersal at a mesoscale within the Rogue River Valley in southern Oregon. We evaluated biotic and abiotic vector behaviour by contrasting two annual species with differing dispersal mechanisms; Achyrachaena mollis (Asteraceae) is a self-pollinating and anemochoric species, and Plectritis congesta (Caprifoliaceae) is biotically pollinated with barochoric seeds. Using landscape genetics methods, we identified features of the study region that conduct or restrict dispersal. We found chloroplast haplotypes were indicative of historic patterns of gene flow prior to human modification of landscapes. Seed dispersal of A. mollis was best supported by models of isolation by distance, while seed-driven gene flow of P. congesta was determined by the distribution of preserved natural spaces and quality habitat. Nuclear genetic structure was driven by both pollen and seed dispersal, and both species responded to contemporary landscape changes, such as urban and agricultural conversion, and habitat availability.

Molecular epidemiology of HIV among people who inject drugs after the HIV-outbreak in Athens, Greece: Evidence for a ‘slow burn’ outbreak

BackgroundNew diagnoses of HIV-1 infection among people who inject drugs (PWID) in Athens, Greece, saw a significant increase in 2011 and a subsequent decline after 2013. Despite this, ongoing HIV-1 transmission persisted from 2014 to 2020 within this population. Our objective was to estimate the time of infection for PWID in Athens following the HIV-1 outbreak, explore the patterns of HIV-1 dispersal over time, and determine the duration from infection to diagnosis. MethodsTime from HIV-1 infection to diagnosis was estimated for 844 individuals infected within 4 PWID-specific clusters and for 8 PWID infected with sub-subtype A6 diagnosed during 2010–2019. Phylogeny reconstruction was performed using the maximum-likelihood method. HIV-1 infection dates were based on molecular clock calculations. ResultsIn total 86 of 92 (93.5%) sequences from PWID diagnosed during 2016–2019 were either related to the previously identified PWID-specific clusters (n = 81) or belonged to a new A6 cluster (n = 5). The median time between infection and diagnosis was 0.42 years during the outbreak period and 0.70 years during 2016–2019 (p < 0.001). The proportion of clustered sequences from PWID was very low at 5.3% during the pre-outbreak period (1998–2009), saw an increase to 41.7% one year before the outbreak in 2010, and consistently remained high during the whole period after 2011, spanning the post-outbreak period (2016–2019) with a range from 92.9% to 100%. ConclusionsThe substantial proportion of clustered infections (93.5%) during 2016–2019 implies a persistent ‘slow burn’ HIV outbreak among PWID in Athens, suggesting that the outbreak was not successfully eliminated. The consistently high proportion of clustered sequences since the onset of the outbreak suggests the persistence of ongoing HIV-1 transmission attributed to injection practices. Our findings underscore the importance of targeted interventions among PWID, considering the ongoing transmission rate and prolonged time from infection to diagnosis.

Dispersal patterns of sandfish (Holothuria scabra) larvae in Manus Province, Papua New Guinea

Dispersal patterns of sandfish (Holothuria scabra) larvae in Manus Province, Papua New Guinea

Understanding the movement and dispersal patterns of released Fopius arisanus (Hymenoptera: Braconidae) parasitoids in a papaya orchard.

Implementation of augmentative biological control requires estimates of parasitoid dispersal from the release point to determine appropriate release density, spacing, and timing. This study evaluated the movement patterns of Fopius arisanus Sonan (Hymenoptera: Braconidae) parasitoids, which have historically been used to control invasive tephritid fruit flies. The wasps were released from the central point, and dispersal was monitored over time using parasitism in sentinel fruit and trap captures at 40 points radiating out from the center (15-240 m). The releases were conducted 4 times during June, July, September, and November 2006. The data showed that there were large declines in dispersal by distance. Parasitism was greatest closest to the release point, within 30 m. Parasitism was also greatest within the first 24h of the release. After 1wk, parasitism decreased from 41% to 1.5% within 30 m. These data correlated strongly with trap capture data, which also showed that parasitoid movement favored the SE region of our release site, roughly corresponding to the overall prevailing winds. Wind speed, relative humidity, and temperature all affected parasitoid movement during our trial, indicating the complex environmental factors that can affect release success. This is the first report of dispersal metrics for F. arisanus. Our findings are in agreement with other similar studies on braconid movement generally and suggest that frequent, high-density releases are most effective since the dispersal of F. arisanus is limited and retention in the environment is low. We discuss our results in the context of international augmentative biological control release programs.

Modeling the larval dispersal and connectivity of Red Snapper (Lutjanus campechanus) in the Northern Gulf of Mexico

Advancements in computing power and improved biophysical dispersal models, have enhanced our ability to realistically simulate distributions and behaviors of fish larvae. In this study, a 1 km high-resolution ocean model capable of capturing the ocean's mesoscale and sub-mesoscale motions is integrated with a biophysical dispersal model that considers a range of larval behaviors. Together they are used to investigate the dispersal and connectivity of Red Snapper (Lutjanus campechanus) larvae, a key species for both commercial and recreational fisheries in the northern Gulf of Mexico (GOM). We quantify how various larval behaviors influence the spatiotemporal dispersal, connectivity and settling of Red Snapper larvae focusing on egg buoyancy, larvae swimming capability, and ontogenetic vertical migration. Alongside habitat preferences, the ocean advection of Red Snapper larvae is crucial in shaping their dispersal patterns. Moreover, our simulations suggest different settling and connectivity characteristics between the eastern and western GOM. These results, indicate the need to divide these regions into distinct entities for stock management, rather than treating them as a unified stock as conventionally done.

Temporal variation of the PM2.5/PM10 ratio and its association with meteorological factors in a South American megacity: Metropolitan Area of Lima-Callao, Peru.

The Metropolitan Area of Lima-Callao (MALC) is a South American megacity that has suffered a serious deterioration in air quality due to high levels of particulate matter (PM2.5 and PM10). Studies on the behavior of the PM2.5/PM10 ratio and its temporal variability in relation to meteorological parameters are still very limited. The objective of this study was to analyze the temporal trends of the PM2.5/PM10 ratio, its temporal variability, and its association with meteorological variables over a period of 5years (2015-2019). For this, the Theil-Sen estimator, bivariate polar plots, and correlation analysis were used. The regions of highest mean concentrations of PM2.5 and PM10 were identified at eastern Lima (ATE station-41.2µg/m3) and southern Lima (VMT station-126.7µg/m3), respectively. The lowest concentrations were recorded in downtown Lima (CDM station-16.8µg/m3 and 34.0µg/m3, respectively). The highest average PM2.5/PM10 ratio was found at the CDM station (0.55) and the lowest at the VMT station (0.27), indicating a predominance of emissions from the vehicular fleet within central Lima and a greater emission of coarse particles by resuspension in southern Lima. The temporal progression of the ratio of PM2.5/PM10 showed positive and highly significant trends in northern and central Lima with values of 0.03 and 0.1 units of PM2.5/PM10 per year, respectively. In the southern region of Lima, the trend was also significant, showcasing a value of 0.02 units of PM2.5/PM10 per year. At the hourly and monthly level, the PM2.5/PM10 ratio presented a negative and significant correlation with wind speed and air temperature, and a positive and significant correlation with relative humidity. These findings offer insights into identifying the sources of PM pollution and are useful for implementing regulations to reduce air emissions considering both anthropogenic sources and meteorological dispersion patterns.