Architectural Conservation Research Articles

Digital Toolkit to Assist the Interpretation of Traditional Masonry Construction

ABSTRACT Masonry construction is ubiquitous and is most typically employed for the construction of fundamental structural architectural elements. It is thus extremely important in architectural conservation, and visual survey, recording and documentation often start with such primary elements. Recording has, however, traditionally been a laborious manual process yielding variable and subjective outcomes. This situation is exacerbated by the need to involve experts to interpret the recorded data, which further increases costs. Recent and ongoing advances in digital reality capture and computer vision afford notable advantages in extracting value from point cloud data with benefits to conservative repair, maintenance, and wider architectural intervention. In this paper, we build on our previous research by the authors and present bespoke algorithms brought together as a ‘digital toolkit’ to automatically segment point clouds into individual masonry units and further characterisation of each unit to support architectural interpretation. The use of this digital toolkit is illustrated using a wall section of Linlithgow Palace (Scotland, UK) as a case study, but it must be emphasised that this form of construction typifies innumerable buildings globally. The toolkit has shown to facilitate rapid and systematic identification of change in masonry construction styles, sizes and geometry, and, when used in conjunction with traditional survey evaluation, it meaningfully assists interpretative capabilities. This combined approach is termed ‘digitally assisted analytical recording’ and it offers the promise of yielding more cost-effective, accurate survey for interpretation.

Recruitment and Residence of Intestinal T Cells - Lessons for Therapy in Inflammatory Bowel Disease.

Targeting leukocyte trafficking in the management of inflammatory bowel disease [IBD] has been a significant therapeutic advance over the past 15 years. However, as with other advanced therapies, phase III clinical trials report response to trafficking inhibitors in only a proportion of patients, with fewer achieving clinical remission or mucosal healing. Additionally, there have been significant side effects, most notably progressive multifocal leukoencephalopathy in association with the α4 inhibitor natalizumab. This article reviews the mechanisms underpinning T cell recruitment and residence, to provide a background from which the strength and limitations of agents that disrupt leukocyte trafficking can be further explored. The therapeutic impact of trafficking inhibitors is underpinned by the complexity and plasticity of the intestinal immune response. Pathways essential for gut homing in health may be bypassed in the inflamed gut, thus providing alternative routes of entry when conventional homing molecules are targeted. Furthermore, there is conservation of trafficking architecture between proinflammatory and regulatory T cells. The persistence of resident memory cells within the gut gives rise to local established pro-inflammatory populations, uninfluenced by inhibition of trafficking. Finally, trafficking inhibitors may give rise to effects beyond the intended response, such as the impact of vedolizumab on innate immunity, as well as on target side effects. With significant research efforts into predictive biomarkers already underway, it is ultimately hoped that a better understanding of trafficking and residence will help us predict which patients are most likely to respond to inhibition of leukocyte trafficking, and how best to combine therapies.

Bio-Stimulated Surface Healing of Historical and Compatible Conservation Mortars.

The main focus of this research was the bio-stimulated healing of cracks in lime mortar samples (historical and newly designed). The investigation started from comprehensive characterisation of historical mortars, while in the next stage a compatible conservation mortar was designed and characterised, with special attention given to the contact zone formation between original and conservation mortars. The next step was the design of a bio-stimulating crack-sealing agent, a two-component liquid system: bacteria culture Sporosarcina pasteurii DSM 33 and nutrients. Both historical and conservation mortar samples were used in order to study their potentials for bio-stimulated surface-crack repair. The experiment lasted for 150 days, allowing the ureolytic bacteria Sporosarcina pasteurii DSM 33 to induce the precipitation of calcium carbonate into cracks and heal the damaged surface of the tested materials. The healing phenomenon was continuously monitored during a period of 150 days. Special attention was given to the evaluation of the morphology, chemical and structural characteristics of the deposits created in/on the surface cracks, monitored by optical microscopy, SEM, XRF and XRD analyses. The obtained results present valuable input for the application of the developed system in real environmental conditions as a solution for the future sustainable architectural conservation of traditionally prepared mortars.

Depleting conjugated C C bonds in tung oil/Eucommia rubber composite film: Fundamentally improve the flexibility and crack resistance for high-performance protective coating

Extending the range of coating materials is a great challenge for sustainable societies. Tung oil generally forms compelling antibacterial and anti-insects coatings, which, however, are difficult to durable due to their intrinsic brittleness. This is because superfluous conjugated CC bonds and the excessive self-crosslinking of molecular chains encourage the rigidity of the polymer network. Herein, we report a design concept of consuming the conjugated trienes on tung oil molecules by the Diels-Alder reaction to enable tung oil/Eucommia rubber composite coating (ERTO) to achieve extraordinary flexibility. A key was to use Eucommia rubber, which can not only consume conjugated CC bonds to suppress self-cross-linking of the tung oil network but also act as a supple segment to form a flexible interpenetrating network with the tung oil molecular chain, rendering the fundamental improvement of the flexibility for ERTO. The results show that ERTO achieves excellent flexibility (easily withstands 180° repeatedly folding), higher stretchability (9.63%), and strong toughness (21.54 MPa). Moreover, the ERTO-based coating exhibits outstanding corrosion resistance (corrosion resistance period up to 7 days) and unprecedented antibacterial properties. These advantages enable the ERTO coating with tremendous potential and offer versatile applications such as architectural conservation, industrial corrosion protection, and the packaging industry.

Application of timber-based techniques for seismic retrofit and architectural restoration of a wooden roof in a stone masonry church

Recent seismic events in Italy highlighted several vulnerabilities in historical buildings belonging to the national architectural heritage. Among others, monumental constructions such as churches appeared to be prone to local (out-of-plane) collapses of masonry walls, often caused by the presence of poor-quality materials and inadequate connections among structural elements. Seismic retrofitting methods are thus necessary, but should also be reversible, not invasive, and aimed to the architectural conservation of the construction, preserving its historical value. In this framework, the potential of timber-based techniques as reversible and effective methods for seismic strengthening and restoration of buildings is promising. This work presents the case study of St. Andrew's Church in Ceto (Brescia, Italy), a stone-masonry monumental building featuring a timber roof from 18th century. Following several inspections commissioned by the curia of Brescia, the church was found in fair structural conditions, with the exception of the wooden roof, having structural elements poorly or not connected among each other and to the masonry. To reduce the evident seismic vulnerability of the church, the roof was retrofitted with plywood panels, allowing for an affordable, rapid, and easily realizable intervention. In this way, the original timber structure could be preserved, creating an adequate load-carrying capacity for static loads, as well as an effective diaphragm against seismic loads. The conducted calculations and numerical analyses showed that the realized intervention greatly improves the seismic behaviour of the building, demonstrating the benefits of wood-based retrofitting and supporting their use for the preservation of architectural heritage.

DETERMINATION OF THE ARCHITECTURAL FEATURES AND STATUS OF PRESERVATION OF THE COMPLEX OF THE ROUND TOWER WITH A BARBICAN AND THE BASTION OF THE MEDZHYBIZH FORTRESS

Based on the available materials of archaeological research, architectural surveys, and documents on emergency and restoration works, the article examines the problems associated with the attribution, research, preservation, and restoration of historical and architectural monuments that have been repeatedly rebuilt. The Round Tower with the Bastion and the Barbican of the Medzhybizh fortress are laid at the base of the analysis. A review and brief analysis of previous studies of the structures mentioned above has been carried out over the past fifty years. The article provides a short historical excursion into the “evolutionary development” of the defensive complex of the Medzhybizh fortress in the 14th-17th centuries. The architectural features of the construction and numerous reconstructions of each presented research object, as well as the historical and military-political prerequisites that led to such large-scale reconstructions, are revealed. The author describes the architectural solutions by which each of the elements is combined with the others into a single defensive complex. Light is also shed on the reasons that caused most of the destruction and damage to the structures. The technical condition of the object and the measures taken during emergency and restoration work during the period of active reconstruction of the complex from 2016 to 2021 inclusive are determined. The list of existing damages with their characteristics and the level of danger they may pose is indicated. The article proposes appropriate measures to eliminate the existing problems, which ultimately will enable the preservation of the objects, their museumification and involvement in the general exhibition space of the Medzhybizh fortress. Finally, the article concludes with conclusions about the current status of architectural conservation of objects and the people's safety there. The sequential order of emergency, conservation, restoration, and additional cleaning and archaeological measures that must necessarily precede the museumification of the south-eastern defensive complex of the Medzhybizh fortress are compared.

Effects of Multisensory Integration through Spherical Video-Based Immersive Virtual Reality on Students’ Learning Performances in a Landscape Architecture Conservation Course

Many courses are transitioning from offline to online instruction in the wake of the COVID-19 pandemic. Landscape architecture conservation courses face problems such as reduced interest in learning, poor learning attitudes and low learning efficiency among students. At the same time, due to the nature of landscape architecture conservation courses, students need more experience to learn well, and many landscape architecture courses do not meet this requirement. Online education also lacks the necessary education scenarios and is not very immersive, making it difficult to meet students’ learning needs. Continued advances in technology have provided new ways for people to connect with nature, increasing awareness and adoption of sustainable landscape architecture practices. To solve the above problems, this study uses multisensory spherical video-based immersive virtual reality technology to develop a VR learning system for landscape architecture conservation courses based on the senses of sight, sound and smell. This system is simple to operate, but interactive and immersive. A quasi-experimental study was also conducted to test the effectiveness of the system. Analyzing the results of the study, students in the experimental group outperformed students in the control group in terms of learning achievements, learning model satisfaction, technology acceptance, flow experience and learning attitudes, which suggests that the use of multisensory spherical video-based immersive virtual reality technology in a landscape architecture conservation course is effective in improving students’ learning performances, and that the study can provide input for the development of other courses.

Comparative study of pre-Hispanic and colonial adobes in Mexico. Preliminary inferences on the effects of the granulometric distribution and used recycled materials in the state conservation of earth architecture

The characterization of the pre-Hispanic and colonial adobes used in the construction of buildings in Mexico was carried out to know the differences between their processes and manufactures. The eight samples obtained correspond to adobe blocks 0.45 m long x 0.35 m wide and 0.12 m thick, which were part of the interiors of houses, the structure of fences, and hacienda galleys. These samples were investigated using X-ray Diffraction, X-ray Fluorescence, and Scanning Electron Microscopy techniques to determine the morphometry of the material and its chemical and mineralogical composition. Likewise, some analyzes were performed to determine their mechanical properties (simple compressive strength), physical properties (granulometry, solid density, cohesion, plasticity index, porosity, and moisture content), and biological (organic matter content). The results obtained in terms of the granulometric distribution indicate that pre-Hispanic adobe has a higher content of sand than silt-clay and gravel, while the colonial adobes present a low or null content of gravel with a higher content of silt-clays. Regarding the organic matter content, the colonial adobe presents the highest percentages compared to those of the pre-Hispanic adobes. Taking into account the above the pre-Hispanic adobes have better resistance and durability than colonial adobes due to their granulometric distribution, low organic matter content, good cohesion, high plasticity index, and the use of materials found in their natural environment, while the colonial used recycled materials, coming from the economic activity to which the hacienda was dedicated, for example, agriculture, mining, livestock, this has given rise to different manufacturing techniques and construction styles that reflect the state of conservation of buildings throughout the pre-Hispanic and colonial times. The granulometric distribution that pre-Hispanic adobe provides favorable physical and mechanical qualities for any construction technique, so it is recommended to use this formula to manufacture resistant and durable adobe.

“The Disappearing Creation”: Architectural Conservation and the Natural Landscape in Tess of the d’Urbervilles

Thomas Hardy’s work as an architect prior to his becoming an author led him to develop the preservationist view that a major aspect of ancient buildings’ value lies in their human associations. In Tess of the d’Urbervilles, Hardy explores the inextricable links among man-made structures, humanity and the natural world, while also demonstrating instances where nature and the built environment – particularly decaying constructions that have not been conserved – can merge to form a unified landscape. The five sites the article uses to examine this notion are: the d’Urberville home of The Slopes; the fowl-house where Mrs d’Urberville’s birds live; the Cross-in-Hand monument; the d’Urberville tombs at Kingsbere; and Stonehenge. While The Slopes provides a prime example of how jarringly architecture can contrast with its natural environment, the fowl-house exemplifies the decaying structure that, because it has not been conserved, has been reclaimed by nature. Cross-in-Hand, the Kingsbere tombs and Stonehenge are all described with plant- and animal-related terminology, emphasizing their integration with and reclamation by their natural environs. Ultimately, the man-made structures in Tess highlight the notion that architectural spaces must be considered in the context of the natural landscape around them. As the humans who occupy these spaces will eventually fade into oblivion, nature must be a fundamental consideration in the architectural process, since nature will ultimately reclaim man-made spaces that are not conserved. In Tess, Hardy’s “green”-ness centres on his emphasis that the natural environment should be just as valued in the architectural conservation process as the built environment.

Lost between legislation and application: a critical reading of Czech post-war architectural conservation policies

ABSTRACT Responding to the reality of post-war architecture in Prague, threatened by demolition and harmful reconstruction, this paper employs critical discourse analysis to examine heritage legislations and documented administrative procedures. The Czech context is a relevant case to the international discussion on heritage definition as an example of the establishment of a rigid authorised discourse that turns conservation processes incoherent and self-referential, especially when evaluating post-war architecture. To safeguard post-war heritage, local conservationists have sought legal protection granted by the Act on State Landmark Conservation upon monument designation. However, designation proposals are being halted and declined to inconsistent criteria and evaluation processes. In response, this paper aims to add to the understanding of the Act and its application by revisiting raised arguments on the designation of five cases and detecting patterns in tendencies and attitudes to estimate the impact of communicated values and influences on the process. The analysis confirms the reported issues of the Act and its application. It also highlights the ideological issues at play that have resulted in a prejudiced judgement towards post-war architecture. Recommendations provided are expected to assist conservationists to strategically structure future proposals being aware of these issues and ultimately contribute to post-war heritage conservation.

Conflict analysis for influence of external opinions on owners decision-making in architectural conservation

Conflict analysis for influence of external opinions on owners decision-making in architectural conservation

Integration between photovoltaic systems and cultural heritage: A socio-technical comparison of international policies, design criteria, applications, and innovation developments

The European legislative framework asks for massive application of renewable energy source (particularly of photovoltaic systems) in the built environment to face the recent energy crisis, reducing energy demand, environmental emissions, and costs. These policies could generate serious preservations problems for architecturally sensitive areas, such as historical towns, historic buildings, and protected landscapes. Inside them, photovoltaic technologies have several benefits for the built environment related to aesthetic appeal, reliability, modularity, scalability, versatility, low maintenance costs, and peak shaving. The major challenge for their application is the presumed negative impact on heritage value. Thus, the diffusion of these systems in the territory is hindered by a social diffidence on their acceptability due to legislative, cultural, technical, and economic barriers. To support the definition of appropriate policies, and realistic targets, the study presents a complete discussion on policy-related design criteria for integrating photovoltaic systems on cultural heritage. This socio-technical analysis can increase a cleaner and integrated energy production, favoring the energy transition and the mitigation of climate changes, respecting heritage and natural values, and considering current energy needs, and innovative developments of photovoltaic systems. The comparison of relevant research projects, scientific studies, awards, and guidelines describes the state of the art of this topic, also identifying 42 international guidelines on energy efficiency, renewable sources, and solar integration on cultural heritage. International recommendations are categorized to find recurring, and applied design criteria for architectural heritage sites, protected landscapes, historic and traditional buildings, and building extensions. Then, updated criteria, pros, and cons for a possible integration are defined through specific focus groups with the Heritage Authorities. These activities are based on international criteria of architectural conservation. The synopsis of these results shows non-negotiable criteria for heritage-compatible solar applications. Finally, the study presents some policy-relevant implications connected with these design criteria, to define realistic energy targets and scenarios, to prepare strategic policy options (e.g., guidelines, rules, policies, and financial incentives) based on updated criteria, correct targets, and recent innovations, to implement existing energy policies in a correct way, to correctly assess restoration design projects, and to evaluate socio-economic trends of innovative photovoltaics' markets.

Conservation and Convergence of Genetic Architecture in the Adaptive Radiation of Anolis Lizards.

AbstractThe G matrix, which quantifies the genetic architecture of traits, is often viewed as an evolutionary constraint. However, G can evolve in response to selection and may also be viewed as a product of adaptive evolution. Convergent evolution of G in similar environments would suggest that G evolves adaptively, but it is difficult to disentangle such effects from phylogeny. Here, we use the adaptive radiation of Anolis lizards to ask whether convergence of G accompanies the repeated evolution of habitat specialists, or ecomorphs, across the Greater Antilles. We measured G in seven species representing three ecomorphs (trunk-crown, trunk-ground, and grass-bush). We found that the overall structure of G does not converge. Instead, the structure of G is well conserved and displays a phylogenetic signal consistent with Brownian motion. However, several elements of G showed signatures of convergence, indicating that some aspects of genetic architecture have been shaped by selection. Most notably, genetic correlations between limb traits and body traits were weaker in long-legged trunk-ground species, suggesting effects of recurrent selection on limb length. Our results demonstrate that common selection pressures may have subtle but consistent effects on the evolution of G, even as its overall structure remains conserved.

Learning from the secondary: Rethinking architectural conservation through ‘barn architecture’

This article explores material culture and peoples’ engagement with built environments from the perspective of vernacular architecture, adaptive reuse and more specifically barn-inspired architecture. Departing from actual cases of conversions that involve material reuse and initiate a correspondence between various more-than-human actors and temporal dimensions, we join the debate around sustainable architecture. We understand sustainability rather as transmission than as arresting change, and we have taken into consideration a broad scope of heritage, including masses of unlisted and abandoned buildings. Adaptive reuse and other comparable forms of using and caring for the outworn existing building stock are practices intended to prolong the lifespan of material resources through reinterpretation. Through barn architecture, we suggest alternative approaches and concepts, such as mending and care, to both fields of architecture and architectural conservation.

Preservation of heritage buildings in Alexandria, Egypt: an application of heritage digitisation process phases and new documentation methods.

Background: Throughout the history of the city, the architecture of Alexandria, Egypt, has been in contact with world cultures, especially those of the Mediterranean sphere. Alexandria is rich with cultural features dating back seven thousand years. In Alexandria, the heritage value of the city has decreased because there is no suitable documentation system for these more recent assets. The development of a new technique for preserving heritage buildings is required. For example, image- based techniques can gather data using photography, panoramic photography, and close-range photogrammetry. In this research, we primarily seek to implement Heritage Digitisation Process Phases (HDPP) and establish new documentation methods in architectural conservation and built-heritage preservation, i.e., Virtual Reality (VR) and Website Heritage Documentation (WHD). Methods: The methodology is designed to preserve and manage cultural heritage using HDPP for the promotion of heritage building preservation in Alexandria. Results: The results show that the application of HDPP has led to the creation of a digital database about the Société Immobilière building, which was chosen as a case study for this research. Conclusions: Implementation of HDPP and usage of new documentation methods i.e., VR and WHD create a digital path to help strengthen its image and connect the place to users, recreational areas are created to communicate and explore the city's architectural history.

Türkiye’de Mimari Mirasın Korunmasında Çalışan Geleneksel Yapı Ustalarının Önemi ve Uygulama Elemanlarının Eğitimleri Üzerine Güncel Bir Değerlendirme

Preservation of the cultural assets with their authentic values and their transfer to the future is directly related to the quality of the conservation and restoration interventions, and therefore to the training and knowledge of the implementers who carry out these interventions. Qualified workforce is an indispensable necessity in this field, which requires special experience and expertise. In this sense, the existence and recognition of traditional masters -who have knowledge, skills and experience in traditional architecture, construction techniques and materials-, their ability to transfer this knowledge to future generations, and the training of young generations as qualified practitioners are of great importance.
 In this study, traditional construction crafts are evaluated in the context of intangible cultural heritage, the issue of identifying existing traditional building masters and ensuring their recognition is brought to the agenda, efforts to raise new generations within the framework of formal and non-formal education are discussed, problems related to professional qualifications are presented and framework suggestions are presented. In the study, the findings are based on the legal frameworks on the subject, the data announced by the relevant institutions and the experience gained from the initiatives in which the authors themselves took part.
 As a result of the findings presented, it is foreseen that the preservation of traditional buildings and construction crafts can be achieved primarily by ensuring the recognition of existing traditional construction masters and securing the environment in which they can transfer their experiences, increasing the application weight of formal education, ensuring the continuity of non-formal education, and employing professionally qualified masters and intermediate staff in practices. It is hoped that this study, which focuses on the education of the people involved in the restoration practices of the cultural assets and the continuity of traditional building mastery, will shed light on the future in the field of architectural conservation.

Quantifying spatiotemporal dynamics of urban building and material metabolism by combining a random forest model and GIS-based material flow analysis

Understanding building metabolism is critical for guiding urban resource management and addressing challenges in urban sustainable development. Key attributes of buildings, including geolocation, footprint, height, and vintage, are crucial to characterizing spatiotemporal patterns of building metabolism. However, these attributes are usually challenging to obtain broadly and automatically, which obscures a comprehensive understanding and accurate assessment of urban metabolism. Moreover, the lack of a finer spatial pattern of these attributes shadows a spatially explicit characterization of material stock and flow in cities. In this study, we took Shenzhen—whose urbanization over the past three decades has been unprecedented in China and even around the world— has been taken as an example to develop a city-level building dataset based on a random-forest model and quantify the spatiotemporal patterns of material metabolism at relatively high spatial resolution (in 500 m × 500 m grids) by combing material flow analysis (MFA) with geographic information system (GIS). The results show that Shenzhen grew from a small town with 281.02 × 106 m3 of buildings in the 1990s to a mega-city with 3585.5 × 106 m3 of buildings in 2018 and expanded both outward and upward from downtown to suburban areas. The urban “weight” (material stock) increased from 92.69 Mt in the 1990s to 1667.8 Mt in 2018 and tended to be saturated, with an average growth rate of 9.5% per year. Spatially, the south-central areas were the largest container of material stocks and generated the most demolition waste. The spatially explicit maps of building three-dimensional (3-D) form and vintage provide detailed information for architectural conservation and could support the decision-making for urban renewal planning. The spatiotemporal patterns of in-use material stocks and potential generation of construction and demolition waste (CDW) provide a benchmark of environmental risk assessment and potential secondary resources to reduce “original” material consumption, which could help alter urban renewal to an environmental-friendly and sustainable trajectory.

A study of Afghan architecture heritage and conservation efforts in Afghanistan

ABSTRACT Built heritage and heritage cities can provide us a strong visual image of national identity; it responds to the architecture's social, cultural, and economic context. Through the architectural heritage, we seek to understand the relation between architecture conservation and the history of architecture. And how does the relationship occur between these two? The history of Afghanistan's architectural heritage reflects the country's primordial legacy and has had played a remarkable role in Afghan civilization. It is needed to visualize, protect and preserve them. The Afghanistan’s architectural heritage sites are notable for various features, one of the most significant features being the architectural significance of ornamentation and elements. These architectural features depict the age in which the building was built, utilizing the technology, craftsmanship, building morphology and styles known at the time. Afghan culture has played a critical part in human civilization throughout its lengthy history and has made significant contributions. Scholarly interest in Afghan culture, including history, archaeology, art, and architecture, has spurred research into Afghan cultural heritage during the past two decades. This study investigates explicitly to reveal the identity of Afghan architecture heritage through history definitions, style, typology, conservation and its contribution to future sustainability.

Data-driven conservation actions of heritage places curated with HBIM

Digital surveying tools provide a highly accurate geometric representation of cultural heritage sites in the form of point cloud data. With the recent advances in interoperability between point cloud data and Building Information Modelling (BIM), digital heritage researchers have introduced the Heritage/Historic Information Modelling (HBIM) notion to the field. As heritage data require safeguarding strategies to ensure their sustainability, the process is closely tied to conservation actions in the architectural conservation field. Focusing on the intersection of the ongoing trends in HBIM research and the global needs for heritage conservation actions, this paper tackles methodological pipelines for the data-driven management of archaeological heritage places. It illustrates how HBIM discourse could be beneficial for easing value-based decision-making in the conservation process. It introduces digital data-driven conservation actions by implementing a novel methodology for ancient building remains in Erythrae archaeological site (Turkey). The research ranges from a) surveying the in-situ remains and surrounding stones of the Heroon remains with digital photogrammetry and terrestrial laser scanning to b) designing a database system for building archaeology. The workflow offers high geometric fidelity and management of non-geometric heritage data by testing out the suitability and feasibility for the study of material culture and the physical assessment of archaeological building remains. This methodology is a fully data-enriched NURBS-based (non-uniform rational basis spline) three-dimensional (3D) model—which is integrated and operational in the BIM environment— for the holistic conservation process. Using a state-of-the-art digital heritage approach can be applied from raw data (initial stages) to decision-making about an archaeological heritage site (final stages). In conclusion, the paper offers a method for data-driven conservation actions, and given its methodological framework, it lends itself particularly well to HBIM-related solutions for building archaeology.

A Chromosome-Length Assembly of the Hawaiian Monk Seal (Neomonachus schauinslandi): A History of "Genetic Purging" and Genomic Stability.

The Hawaiian monk seal (HMS) is the single extant species of tropical earless seals of the genus Neomonachus. The species survived a severe bottleneck in the late 19th century and experienced subsequent population declines until becoming the subject of a NOAA-led species recovery effort beginning in 1976 when the population was fewer than 1000 animals. Like other recovering species, the Hawaiian monk seal has been reported to have reduced genetic heterogeneity due to the bottleneck and subsequent inbreeding. Here, we report a chromosomal reference assembly for a male animal produced using a variety of methods. The final assembly consisted of 16 autosomes, an X, and portions of the Y chromosomes. We compared variants in this animal to other HMS and to a frequently sequenced human sample, confirming about 12% of the variation seen in man. To confirm that the reference animal was representative of the HMS, we compared his sequence to that of 10 other individuals and noted similarly low variation in all. Variation in the major histocompatibility (MHC) genes was nearly absent compared to the orthologous human loci. Demographic analysis predicts that Hawaiian monk seals have had a long history of small populations preceding the bottleneck, and their current low levels of heterozygosity may indicate specialization to a stable environment. When we compared our reference assembly to that of other species, we observed significant conservation of chromosomal architecture with other pinnipeds, especially other phocids. This reference should be a useful tool for future evolutionary studies as well as the long-term management of this species.