Administrative Boundaries Research Articles

SHIPBUILDING OF SOUTHERN UKRAINE: FROM STATE MONOPOLY TO CLUSTER INTEGRATION

The purpose of this article is to determine the prospects of Ukrainian shipbuilding, based on a review of its historical development. Methodology. In this study, the authors used a mix of methods for collecting, systematising and processing information. Primary data was collected through a review of thematic publications and research conducted by predecessors. Retrospective analysis was used to identify trends in the historical development of the shipbuilding sector of the domestic economy. Statistical analysis was used to determine its current state and foreseeable future. Results. Since Porter's introduction of the cluster theory, the Ukrainian shipbuilding business has failed to take advantage of the benefits it has offered. It has been reckless in building cluster potential as a tool for local economic development and community (hromada) management. While most shipbuilding and related enterprises are concentrated in the areas limited by the administrative boundaries of the country's Black Sea regions. Pessimists insist that the chances of success have been lost completely and irrevocably. The authors, on the other hand, based on a generalisation of current practice, observe the Phoenix effect. The authors illustrate it empirically. In particular, on the example of the Ukrainian Maritime Cluster (UMC). Practical implications. The first part of the article explores the former power of Ukrainian shipyards. The second part discusses the constructive initiatives of the modern shipbuilding business. The third part highlights the initiative to create the UMC. Value / Originality. This paper adds to the existing understanding and provides empirical evidence of the strong and untapped potential of the country's shipbuilding cluster. It also focuses on its attractiveness for cooperation with foreign investors after the onset of peace. The originality of this study lies in the holistic study of shipbuilding practice in the context of development. The authors are optimistic despite the war and the tragic consequences that accompany it.

Spatial organization of post-industrial society

The article examines the features of the current stage of urbanization, in particular, the increasing complexity of spatial organization associated with cities overcoming their administrative boundaries, which led to the emergence of agglomerations and urban regions. New urban forms are considered as a result of the formation of a post-industrial society, where the labor market demonstrates greater flexibility than in the industrial one. In addition, the modern transport system makes it possible to easily cover significant distances in a short time and thereby changes the idea of space. Digital technologies have made it possible to transfer a number of interactions (both personal and business) to a remote format, which also contributed to the expansion of urban entities and complicated their management. The author also points out the ambiguous nature of the social consequences of digitalization and algorithmization of urban space. It is noted that smart city technologies, which are positioned as an effective opportunity to counteract uncertainty and manage it, create new vulnerabilities and threats. Special attention is paid to new challenges that modern cities face due to climate change. Thus, the author demonstrates a wide range of social problems relevant to modern urban entities that are becoming in creasingly complex. The article emphasizes that today urban studies is an interdisciplinary field for which sociology is of great importance, allowing us to get an answer to the question of how to improve the quality of life of the population of all spatial forms existing today.

Collaborative governance in action: driving ecological sustainability in the Yangtze River basin

Implementing a collaborative governance framework across administrative boundaries is crucial for preserving the Basin’s ecological integrity and mitigating institutional fragmentation. Based on 19 cases of inter-provincial collaborative governance of ecological environment in the Yangtze River Basin of China, this study uses the fuzzy set qualitative comparative analysis method to explore the influencing factors and complex causal mechanism of the effect of inter-provincial collaborative governance. The results show that technology empowers relationship driving, institutions reinforce interactive driving, and internal and external interaction driving modes promote collaborative governance. Perceived factors are essential in motivating provinces to participate in collaborative governance. External factors play a hygienic role in collaborative governance, and internal factors play a motivated role. The roles of the two types of factors are separate but complementary. In view of this, government should attention to regional environmental concerns, ensuring consistent alignment of internal and external factors and fostering synergies to improve governance effectiveness.

China’s commuting-based metropolitan areas

Using commuting flows derived from cellphone location data at fine geographical levels, this paper presents the first delineation of China’s commuting-based metropolitan areas (MAs). The size distribution of those MAs follows a power law, with larger MAs hosting more skilled workers, more productive firms, and offering higher wage premiums. China’s commuting-based MAs exhibit a few notable features compared to several other large countries. First, commutes are short in both time and distance and rarely cross administrative boundaries. Second, China’s MAs are small relative to the size of the country, with MA sizes highly correlated with the administrative hierarchy. We discuss existing policies that may have contributed to these characteristics. We demonstrate that commuting-based MAs differ substantively from other definitions of Chinese cities. The commuting-based MAs provide a valuable tool for researchers who need to define Chinese cities as local labor markets but are limited by the availability of official delineations.

A Scene–Object–Economy Framework for Identifying and Validating Urban–Rural Fringe Using Multisource Geospatial Big Data

Rapid urbanization has led to the emergence of urban–rural fringes, complex transitional zones that challenge traditional urban–rural dichotomies. While these areas play a crucial role in urban development, their precise identification remains a significant challenge. Existing methods often rely on single-dimensional metrics or administrative boundaries, failing to capture the multi-faceted nature of these zones. This study introduces a novel “Scene–Object–Economy” (SOE) framework to address these limitations and enhance the precision of urban–rural fringe identification. Our approach integrates multisource geospatial big data, including remote sensing imagery, nightlight data, buildings, and Points of Interest (POI), leveraging machine learning techniques. The SOE framework constructs feature from three dimensions: scene (image features), object (buildings), and economy (POIs). This multidimensional methodology allows for a more comprehensive and nuanced mapping of urban–rural fringes, overcoming the constraints of traditional methods. The study demonstrates the effectiveness of the SOE framework in accurately delineating urban–rural fringes through multidimensional validation. Our results reveal distinct spatial patterns and characteristics of these transitional zones, providing valuable insights for urban planners and policymakers. Furthermore, the integration of dynamic population data as a separate layer of analysis offers a unique perspective on population distribution patterns within the identified fringes. This research contributes to the field by offering a more robust and objective approach to urban–rural fringe identification, laying the groundwork for improved urban management and sustainable development strategies. The SOE framework presents a promising tool for future studies in urban spatial analysis and planning.

Depopulation and Changes in Habitat Type in Rural Areas in Aragón (Spain)

Objective: The study aims to examine recent transformations in rural habitats undergoing depopulation in Aragón, Spain, between 2010 and 2018. It seeks to verify changes in habitat concentration patterns and identify the underlying factors. Theoretical Framework: Drawing upon theories of rural exodus and demographic shifts, the research employs the Colas Index (Colas, 1945) to analyze habitat types—dispersed or concentrated. It recognizes the influence of agricultural changes, service provision challenges, and territorial dynamics on rural settlement patterns (Escolano and de la Riva, 2003; Nuninger et al., 2021). Method: The investigation focuses on depopulated municipalities in Aragón, utilizing a comparative analysis of the Colas Index from 2010 to 2018. Administrative boundaries define the study's territorial units, enabling the quantification of habitat changes and an assessment of their direction. The analysis integrates demographic and settlement dynamics to understand habitat evolution. Results and Discussion: Findings indicate varied habitat transformation processes across municipalities, confirming the heterogeneity of the rural landscape (Pinilla and Sáez, 2017). While transformations are not universal, they challenge the traditional link between depopulation and habitat concentration. The Colas Index proves valuable for characterizing habitat dispersion levels, yet its limitations in concentrated areas are acknowledged. Methodological constraints related to administrative boundaries and the complexity of rural-urban continua are also discussed. Research Implications: This study contributes to a nuanced understanding of depopulation impacts on rural habitats, informing territorial planning and demographic policies. It underscores the need for tailored strategies that consider local habitat variability and the potential for revitalization efforts in select areas. Originality/Value: By highlighting the diversity of habitat transitions amidst depopulation, the research offers fresh insights into rural settlement dynamics. Its value lies in demonstrating that depopulation no longer universally leads to habitat concentration, thus updating the scholarly discourse on rural transformation in Spain.

Does urban shrinkage impact energy efficiency?: Evidence from Chinese Counties

Some cities in China are facing challenges due to population loss while also attempting to address energy conservation and emissions reduction. Although urban shrinkage can relieve pressure from energy consumption demands, such as water, electricity and gas, does it improve urban energy efficiency? This study attempts to answer this question. Based on Point of Interest (POI) big data and Global Human Settlement Layer (GHSL) raster data, this study identifies urban shrinkage from the coupling perspective of administrative and economic boundaries. It also examines the impact of urban shrinkage on energy efficiency. The results suggest that Chinese counties’ overall energy efficiency is experiencing a four-stage "decline-rise-decline-rise" trend, and the urban shrinkage of Chinese counties exists in three major areas: the Northeast, the Southwest, and the Centre. Compared to non-shrinking cities, urban shrinkage has a significant negative impact on improving energy efficiency. This impact exhibits significant heterogeneity. Specifically, compared with mature resource cities and cities in Western China, regenerative cities, non-resource cities and cities in Central China have less impact on energy efficiency. In addition, urban shrinkage may impede energy efficiency improvement by hindering industrial structure transformation and upgrading, energy-saving technology innovation, and financial development. Clarifying the relationship between urban shrinkage and energy efficiency is helpful for shrinking cities to change their development strategies, which is critical for sustainable development.

Public administration boundary crossing imperatives: A practitioner’s reflections on pathways toward improved relevance for public service contexts

As a practitioner with boundary spanning interests and roles, I take a reflexive posture to ponder the nature and significance of boundary crossing in public administration. Specifically, I consider how boundary crossing could provide pathways toward greater relevance for public service contexts in South Africa. By bricolage, I derive theoretical and methodological associations across social constructionist perspectives that include relational theory, critical theory and reflexivity. Building on how the boundary crossing imperative is expressed in programme purposes and on brief reviews of public administration interdisciplinarity, I reflect on my experiences in practitioner-academic interactions and inter-institutional projects. From this exploration, I draw provisional conclusions about constraints to and opportunities for beneficial boundary crossing. I incorporate examples of critical considerations to guide the furtherance of education outcomes through boundary interactions between academics and practitioners. The limitations of self-reflexivity in qualitative inquiry are mediated through different data sources and the transparency with which subjective experiences are interpreted. The paper’s contribution is in making explicit a critical inside-out perspective and placing this side by side other empirical endeavours. Amid calls for more relevant and reflexive practices in public administration, the paper provides an example of cross boundary reflections that are still underrepresented and are yet to gain sophistication in practitioner-academic engagement and scholarship.

Topographic and Geodetic Survey for Samarkand's Administrative Boundaries

General Background: Administrative and territorial boundary delineation is vital in the effective governance and economic planning of urban regions globally, with digital technologies increasingly integrated into these processes for accuracy and efficiency. Specific Background: In Uzbekistan, the city of Samarkand’s administrative boundaries are undergoing significant realignment as part of a broader initiative to incorporate strategic urban centers and enable digital land management across administrative zones. Knowledge Gap: Existing methods lack precise integration with digital geospatial frameworks, leaving a gap in high-resolution topographic data essential for clear administrative delineation. Aims: This study seeks to develop and apply an accurate, digitally supported methodology for determining the boundaries of Samarkand's administrative units using advanced geodetic and topographic techniques. Results: By utilizing the CREDO DAT program, this study achieved precise boundary coordinates through the automated processing of survey points, and further analysis was conducted using the Panorama program for detailed map orientation. Novelty: This research presents a unique approach by integrating CREDO DAT with geospatial tools in administrative boundary demarcation, enabling accurate and reproducible results that surpass traditional methods in efficiency and scalability. Implications: The findings support the strategic planning of Samarkand’s infrastructure and resource allocation while also laying the groundwork for applying similar methodologies in other urban regions, advancing Uzbekistan’s digital transformation efforts in land management.Highlights: Digital tools enhance accuracy in administrative boundary mapping. CREDO DAT and Panorama software streamline data processing for precise mapping. This method supports effective urban planning and resource management in Samarkand. Keywords: Administrative Zones, Border, Territory, District, City

Can new infrastructure promote regional economic development? An examination based on administrative boundaries

Can new infrastructure promote regional economic development? An examination based on administrative boundaries

Effects of Injury Registry Data on Policy Making, Hospitalizations, and Mortality: Protocol for a Systematic Review and Meta-Analysis.

Initiated in 2021, a Brazilian project aims to establish a national injury registry, compiling comprehensive data on events and individuals across the country, irrespective of injury severity. The registry integrates information from prehospital and hospital care, diverse health systems lacking interoperability, and sectors such as firefighters and the police. Its primary goal is to enhance health surveillance by providing timely, high-quality information, guiding prevention strategies, and informing policy making. The project still aims to reduce long-term morbidity and mortality associated with injuries. A knowledge gap remains regarding the effects of injury registries in relation to policies and injury outcomes. This protocol outlines a systematic review and meta-analysis to answer "What is the effect of implementation and use of injury registry data on policy making, hospitalization, and mortality?" The systematic review follows PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, focusing on studies reporting results related to the implementation and use of injury registries, including trauma registries. Outcomes of interest include policy making, hospitalization rates or duration, and mortality. Registries within well-defined administrative boundaries will be included. Data will be collected from PubMed, Embase, Scopus, Web of Science, Lilacs, and references. Records will be independently screened by 2 reviewers, with any disagreements resolved through arbitration by a third reviewer. Homogeneous studies, with 3 or more evaluating the same outcome, may undergo meta-analysis. Subgroup analyses by registry type, injury groups, and other selected variables of interest will be conducted. Sensitivity analysis, risk of bias assessment, publication bias evaluation, and quality appraisal will also be performed. This systematic review will run from November 2023 to June 2024. No identical review was found. Search strategies were finalized, the bibliographic search started, duplicates were eliminated, and title and abstract screening began. Of 35 studies retrieved, 85 were excluded due to duplication, leaving 50 for selection. This study is timely, aligning with ongoing national efforts to implement an injury registry. By synthesizing available evidence, we will identify the potential of injury registries to guide the decisions of Brazilian policy makers. PROSPERO CRD42023481528; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=481528. PRR1-10.2196/55029.

Spatial inequality in water access in the US: case studies and solutions

ABSTRACT In addition to the 2.2 million Americans without safe water and sanitation in their homes, millions more regularly face service shut-offs either due to breakages or because of non-payment of bills. Households in areas outside administrative and service boundaries struggle to maintain private systems. Historic disinvestment in majority of African American cities, and decades of underinvestment in water infrastructure, have led to near collapse of many systems. The 2021 Bipartisan Infrastructure and Investment Jobs Act, passed by the United States government, is a historic opportunity to reinvest in water, especially in underinvested communities. These communities need significant assistance to prioritize appropriate investments, apply for available funding, and identify implementation partners. If this does not happen, the inequalities in access will be worsened. Coalitions of technical assistance providers and community-based organizations can help by identifying and matching providers with appropriate funding streams in the short term, while building their capacity to apply for larger federal funds. However, capital investment is only the first step toward equity. It is crucial that water and sewer rates be adjusted to account for household income, and service providers who serve large under-resourced areas receive long-term assistance for operation and maintenance of valuable assets.

Mapping and evaluating spatiotemporal patterns of urban expansion in global earthquake-affected areas: a nighttime light remote sensing perspective

ABSTRACT Amidst the backdrop of frequent global earthquakes, assessing the spatiotemporal dynamics of urban expansion in earthquake-affected areas is imperative for sustainable development insights. The current analyses, however, are primarily focused on administrative units or some specific natural units. Here, we quantified spatiotemporal patterns of urban expansion from 2000 to 2020 in global earthquake-affected areas globally. Specifically, we delineated such areas using data from earthquakes of magnitude 5.5 and above since 1965. Then, employing nighttime light remote sensing data, we extracted urban entities and systematically evaluated the spatiotemporal patterns of urban expansion in earthquake-affected areas. The findings indicate a phase-based differential growth in urban expansion in earthquake-affected areas from 2000 to 2020. The average deceleration factor for urban areas in earthquake-affected areas over the past 20 years is 128.67%. Urban expansion in earthquake-affected areas is growing at a rapid pace, except for Europe and North America. In addition, 66.7% of urban expansion in global earthquake-affected areas presents low-density sprawl and solitary edge expansion trends, potentially affecting population density and land use efficiency. This study offers the most exhaustive analysis of urban expansion in earthquake-affected areas in recent decades and calls for administration beyond administrative boundaries to some extent.

Early Desertification Risk in Advanced Economies: Summarizing Past, Present and Future Trends in Italy

Being located in the middle of Southern Europe, and thus likely representing a particularly dynamic member of Mediterranean Europe, Italy has experienced a sudden increase in early desertification risk because of multiple factors of change. Long-term research initiatives have provided relatively well-known examples of the continuous assessment of the desertification risk carried out via multiple exercises from different academic and practitioner stakeholders, frequently using the Environmentally Sensitive Area Index (ESAI). This composite index based on a large number of elementary variables and individual indicators—spanning from the climate to soil quality and from vegetation cover to land-use intensity—facilitated the comprehensive, long-term monitoring of the early desertification risk at disaggregated spatial scales, being of some relevance for policy implementation. The present study summarizes the main evidence of environmental monitoring in Italy by analyzing a relatively long time series of ESAI scores using administrative boundaries for a better representation of the biophysical and socioeconomic trends of interest for early desertification monitoring. The descriptive analysis of the ESAI scores offers a refined representation of economic spaces in the country during past (1960–2010 on a decadal basis), present (2020), and future (2030, exploring four different scenarios, S1–S4) times. Taken as a proxy of the early desertification risk in advanced economies, the ESAI scores increased over time as a result of worse climate regimes (namely, drier and warmer conditions), landscape change, and rising human pressure that exacerbated related processes, such as soil erosion, salinization, compaction, sealing, water scarcity, wildfires, and overgrazing.

Население Черноморского округа 70-х гг. XIX в.: состояние и структура, влияние Русско-турецкой войны 1877–1878 гг.

In this article, the author examines the society of the Black Sea District during the 1870s of the XIX century. Within the context of colonization processes and the impact of military actions during the Russo-Turkish War of 1877–1878, issues pertaining to the formation of administrative and territorial boundaries, as well as the state and structure of the population in both the pre-war and post-war periods, are discussed. The author presents data regarding the ethnic and religious composition of the population, highlighting its growth from the end of 1872 to the beginning of 1883, and comes to the conclusion that the war had a detrimental effect on demographic processes. The main sources of this study include published official statistical data, normative legal acts, and newspaper publications from “Kavkaz” and “Moscow Vedomosti”, alongside personal materials such as memoirs and analytical works by Arseniy Vasilyevich Vereshchagin, an active participant in the development of the Black Sea coast of the Caucasus during the 1870s.

Internal Self-Determination in Ethiopia

Abstract This paper discusses cluster statehood and its implications on minority ethnic groups. Using the three statehood exercises (South-Western Ethiopian Peoples, Southern Ethiopia and Central Ethiopian regional state) as a case study, this paper highlights the main issues and challenges minority ethnic groups face in the process of statehood exercise. These include the application of the simple majority vote rule in a statehood referendum, the implication of cluster statehood on minority ethnic groups’ rights, the challenge of clustering ethnic minorities without their wishes and restructuring minorities’ ethnic administrative boundaries without a referendum. It concludes that the simple majority followed in statehood referendum makes the role of minority ethnic groups rubber-stamp rather than reflect their real interests. Creating the Central Ethiopian State without a referendum is a flagrant disregard of the constitutional procedure and hinders the full political authority of minority nnp s to decide on their affairs.

Wood trade regions of Russia: clustering approach development

Network analysis of the Russian timber industry was based on the information about timber transactions between Russian companies in 2020. The data were collected from the Unified State Automated Information System Accounting Timber and Transactions with It. The method of graph clustering was developed. The first step is clustering of the hole graph by Leiden algorithm. The second step is drawing of each Leiden created cluster in abstract space using Fruchterman–Reingold layout and extraction of clusters from layout using meanshift algorithm. Such approach helped us to divide many Leiden-created clusters into components. This algorithm has a problem of resolution limit. It tends to combine some medium and small clusters into large ones. Also, a special method was developed to limit the uncertainty of clustering – both Leiden algorithm and Fruchterman–Reingold layout are non-deterministic algorithms. Wood trade clusters vary in size and content. They are rather autonomous. The average share of intra-cluster trade is 89%. The modularity score of our partition is 0.863. Each cluster has been described using open sources from the Internet. The content of the clusters does not contradict the logic of the wood industry processes. The clusters create rather compact areas on the map – wood trade regions. Their borders often overlap with existing administrative boundaries. Five types of network structure of clusters were defined: vertical monocentric, vertical polycentric, horizontal, dendritic, simple. There are three factors of clustering in wood industry of Russia: production chains (4 types – pulp, plywood, lumber, chipboard chains), demand chains (redistribution of raw material between manufacturers within the cluster, accumulation of wood volumes for some enterprises outside the cluster, wood trade between traders within the cluster), common holder. We have shown that existing approaches to cluster detection based on location quotients often misrepresent economic networks.

Multi-hazard, multidimensional disaster risk validation in selangor’s three urban districts, Malaysia

Considering the increasing impact of natural hazard-related disasters in Malaysia, understanding and evaluating integrated disaster risk must consider multi-hazard and multidimensional vulnerability at the local level, particularly in developing industrial nations like Malaysia. Therefore, this study proposes an improved methodology for conducting an integrated disaster risk assessment index (IDRI) mapping to measure disaster risk within local administrative boundaries in Malaysia. In this study, multi-hazard spatial overlapping combined two common hazards in Malaysia, which are floods and landslides. This study used multidimensional vulnerability, which encompasses six dimensions, 16 subdimensions, and 54 indicators. Researchers applied this approach in three urban districts of Selangor, Malaysia: Sepang, Kuala Langat, and Hulu Langat, which are located within the Langat River catchment and consist of 17 subdistricts. Overall, 32.9% of the total study area was found to be at risk, with 4.3% in the very high-risk area. In comparison with the latest flood events in 2021, the IDRI components were highly correlated with disaster impact. In conclusion, the contribution of this study provides a novel perspective on disaster risk assessment by addressing several types of hazards and multidimensional vulnerability, as compared to the previous methodology focusing on a single hazard and a physical vulnerability factor.

Hobli wise hydro geomorphological evaluation of the groundwater prospects mapping

ABSTRACT Numerous studies highlight the urgent issue of groundwater depletion due to overexploitation. The United Nations’ World Water Development Report (2023) warns that if current extraction rates persist, many regions could face severe groundwater shortages in the coming decades. A 2021 study in Nature reports that about one-third of the world’s largest groundwater basins are depleting faster than they are replenished, escalating the risk of critical shortages. In Chickballapur District, excessive agricultural activity has led to an imbalance between groundwater loss and recharge. To address this challenge, a weighted overlay analysis of spatial layers in QGIS was employed to identify potential groundwater zones. This methodical approach involved mapping topographic features and integrating six spatial layers: slope, geomorphology, lithology, drainage, lineament and land use/cover. Each subcategory was ranked and scored based on expert opinion and existing literature. The Central Ground Water Board data was used to validate the resulting groundwater prospect map. The study further included an assessment of groundwater prospects across administrative units by superimposing the administrative boundaries on the final map. Calculating the percentage of land within each groundwater prospect category is crucial for effective groundwater management at the administrative level.

Prevalence and determinants of stunting and anaemia in children aged 6-23 months: A multilevel analysis from rural Ethiopia.

Low- and middle-income countries shoulder the greatest burden of stunting and anaemia in children. This calls for prompt and effective intervention measures, while the contributing factors are not fully understood. This study evaluates determinants spanning from individual-, household- and community levels including agroecology and antinutrients as unique sets of predictors. Primary data were collected from 660 rural households representing the midland (ML), highland, and upper highland (UHL) agroecological zones from northern Ethiopia. The study relates several predictors to stunting and anaemia in children aged 6-23 months. We found 49.1% and 49.7% of children were stunted and anaemic, respectively. Children living in the ML are approximately twice more likely to be stunted adjusted odds ratio (AOR: 1.869; 95% CI: 1.147-3.043) than in the UHL. The risk of stunting increases by 16.3% and 41.9% for every unit increase in phytate-to-zinc and phytate-to-iron molar ratios, respectively. A 10% increase in mean aggregated crop yield was observed to reduce the likelihood of stunting occurrence by 13.6%. Households lacking non-farm income-generating opportunities, travel longer time to access the marketplace and poor health service utilisation were associated with increased risk of stunting. Low diversity of child's diet, age of the child (18-23 months) and mothers at a younger age are significantly associated with stunting. Risk of anaemia in children is high amongst households with unimproved water, sanitation, and hygiene practices, younger age (6-11 months) and mostly occurs amongst boys. Children in the ML had a 55% reduced risk of being anaemic (AOR: 0.446; 95% CI: 0.273-0.728) as compared to the UHL. Therefore, the influence of these factors should be considered to tailor strategies for reducing undernutrition in children of 6-23 months in rural Ethiopia. Interventions should go beyond the administrative boundaries into targeting agroecological variation.