Spatial Genetic Analyses Research Articles

Barriers and corridors: Assessment of gene flow and movement among red panda populations in eastern Himalayas

Landscape features can impede dispersal, gene flow, and population demography, resulting in the formation of several meta-populations within a continuous landscape. Understanding a species' ability to overcome these barriers is critical for predicting genetic connectivity and population persistence, and implementing effective conservation strategies. In the present study, we conducted a fine-scale spatial genetic analysis to understand the contemporary gene flow within red panda populations in the Eastern Himalayas. Employing geometric aspects of reserve design, we delineated the critical core habitats for red pandas, which comprise 14.5 % of the landscape (12,189.75 Km2), with only a mere 443 Km2 falling within the protected areas. We identified corridors among the core habitats, which may be vital for the species' long-term genetic viability. Furthermore, we identified substantial landscape barriers, including Sela Pass in the western region, Siang river in the central region, and the Dibang river, Lohit river, along with Dihang, Dipher, and Kumjawng passes in the eastern region, which hinder gene flow. We suggest managing red panda populations through the creation of Community Conservation Reserves in the identified core habitats, following landscape-level management planning based on the core principles of geometric reserve design. This includes a specific emphasis on identified core habitats of red panda (CH-RP 5 and CH-RP 8) to facilitate corridors and implement meta-population dynamics. We propose the development of a comprehensive, long-term conservation and management plan for red pandas in the transboundary landscape, covering China, Nepal, and Bhutan.

Material Selection for Restoration of Genetic Diversity of Abies koreana on Mt. Jirisan in South Korea

A strategy is required for selecting appropriate materials for the restoration of Abies koreana on Mt. Jirisan, where the habitat of A. koreana is continuously shrinking. The current study aimed to analyze the genetic characteristics of A. koreana in three subpopulations (Banyabong, Byeoksoryeng, and Cheonwangbong) on Mt. Jirisan using 10 nuclear simple sequence repeat (nSSR) markers and calculate the sampling distance for each subpopulation for avoiding genetically similar samples. Based on the calculated sampling distance, we proposed the size of a sample containing more than 95% of the alleles at a frequency greater than 0.05. AMOVA showed that the difference in genetic variation across subpopulations of A. koreana on Mt. Jirisan was small, approximately 3% of the total. Spatial genetic structure analysis results suggested that it would be appropriate to collect samples of the Banyabong subpopulation at intervals of 10 m or more, when sampling A. koreana, whereas for the Byeoksoryeong and Cheonwangbong subpopulations, samples should be collected at intervals of 20 m or more. Results of random sampling of 5 to 30 individuals indicated that, by applying a 10 m distance within the Banyabong subpopulation, more than 95% of the total alleles with a frequency ≥ 0.05 were secured when more than 25 individuals were extracted. Therefore, as a restoration strategy for A. koreana on Mt. Jirisan, we proposed the collection of more than 25 samples, keeping 10 m distance within the Banyabong subpopulation, which has a relatively high genetic diversity.

Genetic data to describe the hybrid zone between Bufo bufo (Linnaeus, 1758) and Bufo verrucosissimus (Pallas, 1814) in northeastern Türkiye

Abstract Hybrid zones are geographic areas where individuals from distinct taxa meet, mate, and hybridize. These zones may have complex histories, but many of them originated relatively recently, during climatic oscillations in the Quaternary, following range shifts of formerly isolated, well-differentiated lineages. The Bufo bufo species group comprises four species distributed over the Western Palearctic. Whereas the contact zone between Bufo bufo and B. spinosus in western Europe has been well characterized, little is known about other species contacts. Here we focused on the contact between B. verrucosissimus and B. bufo in northeastern Türkiye, using mtDNA and microsatellite markers to describe genetic structure and patterns of admixture in the hybrid zone based on Bayesian clustering and cline analyses. Both species meet in a narrow contact zone at Rize province, with restricted introgression suggesting barriers to hybridization consistent with species status. Spatial population genetic analyses of microsatellite data pinpoint a possible enclave population of B. bufo at the Borçka district in Artvin province, isolated within the B. verrucosissimus range. The centers of the microsatellite and mtDNA-based clines are slightly displaced, with B. verrucosissimus mtDNA introgressing about 33 km W of the nuclear contact. Hybrid zone dynamics seem to be associated with range shifts mediated by Pleistocene glacial cycles and/or sex-biased dispersal.

Regional (south‐eastern Pacific Ocean) population genetics and global phylogeography of two endangered highly migratory pelagic sharks, the blue shark Prionace glauca and shortfin mako Isurus oxyrinchus

Abstract The blue shark Prionace glauca and the shortfin mako Isurus oxyrinchus are two large and highly migratory sharks inhabiting temperate and tropical waters worldwide that are heavily targeted by artisanal and industrial fisheries. The International Union for Nature Conservation classifies the blue shark and shortfin mako as ‘Near Threatened’ and ‘Vulnerable’, respectively, in the Nature Red List of Threatened Species v. 2019‐2. This study examined the population genetics of the shortfin mako and blue sharks at a regional (south‐eastern Pacific Ocean) and global scale. The null hypothesis of no genetic discontinuities among ocean basins and/or between hemispheres was tested using two mitochondrial markers suitable for population genetics inference in these species: the non‐coding control region and the protein‐coding gene cytochrome c oxidase I in I. oxyrinchus, and the control region and cytochrome b in P. glauca. Spatial genetic analyses suggested a single and two genetic clusters co‐occurring along the south‐eastern Pacific Ocean in the shortfin mako and blue shark, respectively. Phylogeographic analyses, migration estimates, haplotype networks and AMOVAs demonstrated that the two species exhibit an overall pattern of high genetic connectivity among hemispheres and across ocean basins with a signature of shallow genetic structuring worldwide. This study has generated valuable information for the management and conservation of heavily exploited sharks and highlights the need for additional inclusive research programmes assessing inter‐regional genomic discontinuities using more statistically powerful genetic markers to determine with precision population genetic discontinuities (if any) in these and other highly migratory sharks.

A practical spatial analysis method for elucidating the biological mechanisms of cancers with abdominal dissemination in vivo

Elucidation of spatial interactions between cancer and host cells is important for the development of new therapies against disseminated cancers. The aim of this study is to establish easy and useful method for elucidating spatial interactions. In this study, we developed a practical spatial analysis method using a gel-based embedding system and applied it to a murine model of cancer dissemination. After euthanization, every abdominal organ enclosed in the peritoneum was extracted en bloc. We injected agarose gel into the peritoneal cavities to preserve the spatial locations of the organs, including their metastatic niches, and then produced specimens when the gel had solidified. Preservation of the original spatial localization was confirmed by correlating magnetic resonance imaging results with the sectioned specimens. We examined the effects of spatial localization on cancer hypoxia using immunohistochemical hypoxia markers. Finally, we identified the mRNA expression of the specimens and demonstrated the applicability of spatial genetic analysis. In conclusion, we established a practical method for the in vivo investigation of spatial location-specific biological mechanisms in disseminated cancers. Our method can elucidate dissemination mechanisms, find therapeutic targets, and evaluate cancer therapeutic effects.

Fluctuating fine-scale spatial genetic structure in the common shrews (Eulipotyphla, Mammalia).

The spatial genetic structure is a topical issue in the studies of various aspects of ecology and evolution. Using the multilocus autocorrelation method with hypervariable microsatellite genetic markers, we investigated a fine-scale pattern of genetic structure in 5 local populations of the common shrew Sorex araneus separated by distances of 300-1000 m (the Moscow chromosomal race). Spatial genetic autocorrelation analysis based on 5 microsatellite loci (expected heterozygosity >0.79) with 90 alleles revealed a consistent pattern of significant positive genetic structure. By testing the autocorrelation at multiple scales from 25 to 500 m, we found that positive spatial genetic structure is detectable in distance classes of <500 m. The weaker spatial genetic structure positively correlated with a higher ratio of nonresident individuals to residents' activity (number of captures). In contrast to nonresident animals, the residents demonstrated prominent genetic structure. Genetic difference (FST ) between the populations was significant (0.016-0.051) and comparable with that between populations of different races analyzed previously (0.016-0.038). FST was not associated with geographic distance. These demographic patterns allowed us to propose a scheme of genetic-structure dynamics involving periodic appearance of more related local groups and renewal of allelic profiles from а common pool where the alleles are mixed. The scheme predicts fluctuating genetic structure and random similar differences among local populations.

Comparative reproductive ecology of two sister Asarum species (Aristolochiaceae) in relation to the evolution of elongated floral appendage.

Genus Asarum (Aristolochiaceae) shows diverse floral morphology and is hypothesized to have diversified as a result of pollinator-mediated selection. Yet most aspects of their reproductive ecology, including pollinators, remain unclear. This study focuses on A. costatum and A. minamitanianum in Japan, a sister species pair having remarkable differences in calyx lobe length (10-20 mm and 70-180 mm, respectively). The objectives of this study are to elucidate multiple aspects of reproductive ecology of these two species and obtain evolutionary insights into floral organ elongation. We adopted combined approaches, including field observations, molecular analyses and cultivation experiments, such as pollinator observation for 3 years, fine-scale spatial genetic analysis of 769 individuals, paternity analysis based on 566 seeds over 4 years, and control pollination experiments. Both Asarum species had strong spatial genetic structures, indicating limited seed dispersal. Pollinator observation revealed that flies and ground-dwelling insects visited flowers of both species, but that the pollinator fauna differed between the species. The visitation rate of flies was extremely low but was more than twice as high in the species with an elongated floral appendage. Paternity analysis revealed A. minamitanianum was predominantly outcrossing, while A. costatum showed a wide range of selfing rates among fruits. These two Asarum species are likely adapted to fly pollination in the shady forest understorey, where available pollinator fauna is limited. In addition, although its function remains unclear, the elongated calyx lobe of A. minamitanianum could have evolved for effective pollen dispersal by attracting fly visitors.

KLFDAPC: a supervised machine learning approach for spatial genetic structure analysis.

Geographic patterns of human genetic variation provide important insights into human evolution and disease. A commonly used tool to detect and describe them is principal component analysis (PCA) or the supervised linear discriminant analysis of principal components (DAPC). However, genetic features produced from both approaches could fail to correctly characterize population structure for complex scenarios involving admixture. In this study, we introduce Kernel Local Fisher Discriminant Analysis of Principal Components (KLFDAPC), a supervised non-linear approach for inferring individual geographic genetic structure that could rectify the limitations of these approaches by preserving the multimodal space of samples. We tested the power of KLFDAPC to infer population structure and to predict individual geographic origin using neural networks. Simulation results showed that KLFDAPC has higher discriminatory power than PCA and DAPC. The application of our method to empirical European and East Asian genome-wide genetic datasets indicated that the first two reduced features of KLFDAPC correctly recapitulated the geography of individuals and significantly improved the accuracy of predicting individual geographic origin when compared to PCA and DAPC. Therefore, KLFDAPC can be useful for geographic ancestry inference, design of genome scans and correction for spatial stratification in GWAS that link genes to adaptation or disease susceptibility.

Population genetic structure of wolves in the northwestern Dinaric-Balkan region.

The Balkan Peninsula and the Dinaric Mountains possess extraordinary biodiversity and support one of the largest and most diverse wolf (Canis lupus) populations in Europe. Results obtained with diverse genetic markers show west‐east substructure, also seen in various other species, despite the absence of obvious barriers to movement. However, the spatial extent of the genetic clusters remains unresolved, and our aim was to combine fine‐scale sampling with population and spatial genetic analyses to improve resolution of wolf genetic clusters. We analyzed 16 autosomal microsatellites from 255 wolves sampled in Slovenia, Croatia, Bosnia and Herzegovina (BIH), and Serbia and documented three genetic clusters. These comprised (1) Slovenia and the regions of Gorski kotar and Lika in Croatia, (2) the region of Dalmatia in southern Croatia and BIH, and (3) Serbia. When we mapped the clusters geographically, we observed west‐east genetic structure across the study area, together with some specific structure in BIH–Dalmatia. We observed that cluster 1 had a smaller effective population size, consistent with earlier reports of population recovery since the 1980s. Our results provide foundation for future genomic studies that would further resolve the observed west‐east population structure and its evolutionary history in wolves and other taxa in the region and identify focal areas for habitat conservation. They also have immediate importance for conservation planning for the wolves in one of the most important parts of the species’ European range.

PATH-29. GLIOBLASTOMA TUMOR CLASSIFICATION BASED ON SPATIAL ANALYSIS OF ONCOGENIC AMPLIFICATIONS AND PROTEIN EXPRESSION

Abstract Heterogeneity of glioblastoma (GBM) has been extensively studied in recent years with identification of oncogenic drivers of GBM cellular subtypes. However, little is known about how these cells interact with each other or with the surrounding tumor microenvironment (TME). We employed spatial protein profiling targeting immune and neuronal markers (79 proteins) coupled with single-cell spatial maps of fluorescence in situ hybridization (FISH) for EGFR, CDK4, and PDGFRA on human GBM tissue sections. Several cores from 20 GBM samples were collected to create a tissue microarray, and 96 regions of interests were profiled with 37,844 nuclei for oncogenic amplification screen. Spatial protein profiling identified strong correlation of certain immune markers, TAU-associated proteins, and oligodendrocyte-enriched protein groups and overall high intratumor heterogeneity of TME. Our single-cell quantification of FISH signals showed differences among tumors based on the prevalence of dual amplification of EGFR and CDK4 within a cell relative to single oncogene amplified cells. High relative frequency of dual amplification was associated with increased expression of immune-related markers and decreased expression of EGFR protein. Moreover, this protein expression signature was associated with survival in another GBM dataset. Here, we present spatial genetic analysis at the single cell level coupled with protein expression profiles associated with tumor microenvironment. Our results suggest that assessment of genetic heterogeneity in GBM could potentially drive improved patient stratification and treatment.

Spatial Autocorrelation Analysis Using MIG-seq Data Indirectly Estimated the Gamete and Larval Dispersal Range of the Blue Coral, Heliopora coerulea, Within Reefs

Spatial autocorrelation analysis is a well-established technique for detecting spatial structures and patterns in ecology. However, compared to inter-population genetic structure, much less studies examined spatial genetic structure (SGS) within a population by means of spatial autocorrelation analysis. More SGS analysis that compares the robustness of genome-wide single nucleotide polymorphisms (SNPs) and traditional population genetic markers in detecting SGS, and direct comparison between the estimated dispersal range based on SGS and the larval dispersal range of corals directly surveyed in the field would be important. In this study, we examined the SGS of a reef-building coral species, Heliopora coerulea, in two different reefs (Shiraho and Akaishi) using genome-wide SNPs derived from Multiplexed inter-simple sequence repeat (ISSR) genotyping by sequencing (MIG-seq) analysis and nine microsatellite loci for comparison. Microsatellite data failed to reveal significant spatial patterns when using the same number of samples as MIG-seq, whereas MIG-seq analysis revealed significant spatial autocorrelation patterns up to 750 m in both Shiraho and Akaishi reefs based on the maximum significant distance method. However, detailed spatial genetic analysis using fine-scale distance classes (25–200 m) found an x-intercept of 255–392 m in Shiraho and that of 258–330 m in Akaishi reef. The latter results agreed well with a previously reported direct field observation of larval dispersal, indicating that the larvae of H. coerulea settled within a 350 m range in Shiraho reef within one generation. Overall, our results empirically demonstrate that the x-intercept of the spatial correlogram agrees well with the larval dispersal distance that is most frequently found in field observations, and they would be useful for deciding effective conservation management units for maintenance and/or recovery within an ecological time scale.

Spatial and Temporal Genetic Analyses of Phyllosticta citricarpa in Two Lemon Orchards in South Africa Reveal a Role of Asexual Reproduction Within Sexually Reproducing Populations.

Citrus black spot (CBS), caused by Phyllosticta citricarpa, is a disease that affects citrus worldwide. In different regions of the world where both mating types occur, reports differ as to whether asexually produced pycnidiospores play an important role in the epidemiology of CBS and fruit infections. Therefore, we investigated the potential role of pycnidiospores in two lemon orchards in South Africa by using microsatellite-based analysis of fruit populations over time (two seasons) and space (distance). The two orchards were situated in the semiarid North West province (NW) and subtropical Mpumalanga province (MP). Each population contained both mating types in 1:1 ratios, and linkage disequilibrium analysis indicated a random mating population. A total of 109 and 94 multilocus genotypes (MLGs) were detected across the two seasons in the NW and MP orchards, respectively. Psex analyses indicated that most MLGs probably resulted from sexual reproduction, but there were six predominant MLGs in each orchard that were probably replicated via asexual reproduction. Each of the predominant MLGs was monomorphic for mating type. In the NW, five predominant and widespread MLGs caused 46 and 44% of the fruit infections in the two seasons, whereas in MP, three MLGs caused 34 and 48% of the infections. Asexual reproduction in both orchards was supported by low MLG evenness values in all populations. In both orchards, distance was not a reliable predictor of population genetic substructuring or season. Populations of P. citricarpa in the MP and NW orchards were significantly genetically differentiated from each other.

Extraction of spatial genetic characteristics and analysis of 1930s Korean Urban Hanok based on application of space syntax

ABSTRACT This paper presents an analysis of an Urban Hanok (improved Korean traditional housing), created in the process of Seoul’s urbanization since the 1930s as anew housing type from traditional Hanoks, using aspace syntax methodology to uncover the underlying genotype. The genotype of the Urban Hanok plan layout, originating from the urban residential areas organized in the 1930s, was analyzed and compared. The results indicate that the Madang-centered organization is the underlying spatial structure of the 1930s Urban Hanok. Diachronic examination of the sample in terms of sectoral differentiation has identified three groups: (a) the house organized with three central spaces (Madang– Daecheong– Deamungan or stairs), (b) the house organized with three central spaces (Madang– Mediation Space– Daecheong), and (c) the house organized with two central spaces (Madang– Sarang Madang). When converted to aJustified graph, group (a) is classified into aTree-Shape, and an Umbrella-Shape, group (b) is classified into an extended Tree-Shape, and group (c) is classified into aRing-Shape. Characteristics of the spatial structure in the Urban Hanok layout and their meanings were identified through this research. The implication of the Madang-centered layout type, most common in Urban Hanoks.

Regional population genetics and global phylogeography of the endangered highly migratory shark Lamna nasus: Implications for fishery management and conservation

Abstract The porbeagle shark Lamna nasus is a large highly migratory shark distributed in cold and temperate marine waters of the North Atlantic and Southern Hemisphere (SH). According to the International Union for Conservation of Nature, the porbeagle is assessed globally as Vulnerable and regionally as Critically Endangered in the North Atlantic and the Mediterranean Sea. This study explored, for the first time, the population genetics of L. nasus at a regional (south‐east Pacific Ocean) and global scale. In this study, the null hypotheses of no genetic discontinuities among populations (i) within the SH, and (ii) between the SH and Northern Hemisphere (NH) were tested. Also, the demographic history of L. nasus in different ocean basins was assessed. Two mitochondrial markers (Control Region [CR] and cox1) well suited for population genetics inferences in sharks were used. Spatial–genetic analyses suggested two genetic clusters co‐occurring in the south‐eastern Pacific Ocean. A two‐way ANOVA using the cox1 but not the CR mtDNA fragment detected an effect of genetic identity on shark body size. Phylogeographic analyses, haplotype networks, and analyses of molecular variance demonstrated genetic differences between populations from the NH and SH but not among populations in the SH. Migration estimates indicated limited current maternal gene flow between the two hemispheres but high gene flow within hemispheres. Two well‐defined haplotype groups with star‐like shapes inhabited all ocean basins in the SH. These results could reflect a historical scenario of reproductive isolation and more recent mixture among previously isolated populations in the SH. A Bayesian skyline plot analysis indicated sudden population expansion in the SH occurring ~100–125 kya. This study highlights the need for additional studies focusing on the population genomics (using nuclear markers, i.e. single nucleotide polymorphisms) and the general biology of L. nasus to explore the existence of genetically dissimilar populations in the SH. Such studies will help implementing efficient genetic monitoring programmes.

Genetic structure of recently fragmented suburban populations of European stag beetle.

Habitat loss and fragmentation due to urbanization can negatively affect metapopulation persistence when gene flow among populations is reduced and population sizes decrease. Inference of patterns and processes of population connectivity derived from spatial genetic analysis has proven invaluable for conservation and management. However, a more complete account of population dynamics may be obtained by combining spatial and temporal sampling. We, therefore, performed a genetic study on European stag beetle (Lucanus cervus L.) populations in a suburban context using samples collected in three locations and during the period 2002–2016. The sampling area has seen recent landscape changes which resulted in population declines. Through the use of a suite of F ST, clustering analysis, individual assignment, and relatedness analysis, we assessed fine scale spatiotemporal genetic variation within and among habitat patches using 283 individuals successfully genotyped at 17 microsatellites. Our findings suggested the three locations to hold demographically independent populations, at least over time scales of relevance to conservation, though with higher levels of gene flow in the past. Contrary to expectation from tagging studies, dispersal appeared to be mainly female‐biased. Although the life cycle of stag beetle suggests its generations to be discrete, no clear temporal structure was identified, which could be attributed to the varying duration of larval development. Since population bottlenecks were detected and estimates of effective number of breeders were low, conservation actions are eminent which should include the establishment of suitable dead wood for oviposition on both local and regional scales to increase (re)colonization success and connectivity among current populations.

The Influence of a Seedling Recruitment Strategy and a Clonal Architecture on a Spatial Genetic Structure of a Salvia brachyodon (Lamiaceae) Population.

By performing a high-resolution spatial-genetic analysis of a partially clonal Salvia brachyodon population, we elucidated its clonal architecture and seedling recruitment strategy. The sampling of the entire population was based on a 1 × 1 m grid and each sampled individual was genotyped. Population-genetic statistics were combined with geospatial analyses. On the population level, the presence of both sexual and clonal reproduction and repeated seedling recruitment as the prevailing strategy of new genets establishment were confirmed. On the patch level, a phalanx clonal architecture was detected. A significant negative correlation between patches’ sizes and genotypic richness was observed as young plants were not identified within existing patches of large genets but almost exclusively in surrounding areas. The erosion of the genetic variability of older patches is likely caused by the inter-genet competition and resulting selection or by a random die-off of individual genets accompanied by the absence of new seedlings establishment. This study contributes to our understanding of how clonal architecture and seedling recruitment strategies can shape the spatial-genetic structure of a partially clonal population and lays the foundation for the future research of the influence of the population’s clonal organization on its sexual reproduction.

Invalidation of taxa within the silvery wooly monkey (Lagothrix lagothricha poeppigii, Atelidae, Primates)

The systematics of the Humboldt’s wooly monkeys (L. lagothricha; Atelidae) is essential to preserve this Neotropical primate species. Traditionally, four morphological subspecies have been described, which recently have been molecularly confirmed. However, no population genetics studies have been carried out throughout the geographical distribution of one of these subspecies, Lagothrix lagothricha poeppigii. For this reason, we analyzed nine mitochondrial genes of L. l. poeppigii mainly collected from the Ecuadorian and Peruvian Amazon in order to better understand the evolutionary history of this taxon. The mitochondrial genetic diversity levels (haplotype and nucleotide diversity) we estimated are likely the highest yet reported for L. lagothricha. Our results did not detect important genetic structure within L. l. poeppigii. Furthermore, our phylogenetic analyses did not detect any relevant molecular cluster in the area where Groves hypothesized the existence of L. poeppigii castelnaui. Therefore, based on these data, castelnaui is not a valid taxon from a molecular perspective. The most differentiated subpopulation within L. l. poeppigii was from Morona-Santiago province (Ecuador) and had a genetic distance of 0.8–1.2% relative to the other subpopulations studied. However, this genetic distance range is within the variability found within a population. We estimated the mitochondrial temporal diversification within L. l. poeppigii to have occurred during the Pleistocene, 1.8–1.2 million years ago. Similarly, all our analyses detected a strong Pleistocene female population expansion for this taxon. Diverse spatial genetic analyses, perhaps with the exception of Monmonier’s Algorithm, did not detect differentiated taxa within the area analyzed for L. l. poeppigii. These genetics results could be of importance to conservation efforts to preserve this taxon as one unit.

Shared Regulatory Pathways Reveal Novel Genetic Correlations Between Grip Strength and Neuromuscular Disorders.

Muscle weakness is a common consequence of both aging (sarcopenia) and neuromuscular disorders (NMD). Whilst genome-wide association (GWA) studies have identified genetic variants associated with grip strength (GS; measure of muscle strength/weakness) and NMDs, including multiple sclerosis (MS), myasthenia gravis (MG) and amyotrophic lateral sclerosis (ALS), it is not known whether there are common mechanisms between these phenotypes. To examine this, we have integrated GS and NMD associated genetic variants (single nucleotide polymorphisms; SNPs) in a multimorbid analysis that leverages high-throughput chromatin interaction (Hi-C) data and expression quantitative trait loci data to identify target genes (i.e., SNP-mediated gene regulation). Biological pathways enriched by these genes were then identified using next-generation pathway enrichment analysis. Lastly, druggable genes were identified using drug gene interaction (DGI) database. We identified gene regulatory mechanisms associated with GS, MG, MS, and ALS. The SNPs associated with GS regulate a subset of genes that are also regulated by the SNPs of MS, MG, and ALS. Yet, we did not find any genes commonly regulated by all four phenotype associated SNPs. By contrast, we identified significant enrichment in three pathways (mTOR signaling, axon guidance, and alcoholism) that are commonly affected by the gene regulatory mechanisms associated with all four phenotypes. 13% of the genes we identified were known drug targets, and GS shares at least one druggable gene and pathway with each of the NMD phenotypes. We have identified significant biological overlaps between GS and NMD, demonstrating the potential for spatial genetic analysis to identify common mechanisms between potential multimorbid phenotypes. Collectively, our results form the foundation for a shift from a gene to a pathway-based approach to the rationale design of therapeutic interventions and treatments for NMD.

Molecular assessment of natural disturbance regime in a temperate swamp forest

Advanced knowledge of forest disturbance regimes (the temporal and spatial patterns of periodic disturbances) has key relevance to implementation of effective managements for forest communities. For many forest ecosystems such knowledge is inadequate or is lacking. Spatially explicit simulations, testing effects of alternative disturbance regimes on fine-scale spatial genetic structure (FSGS) may provide information on key components of forest disturbance regimes. Here, we compare FSGSs assessed using 18 microsatellite markers with spatially explicit simulations, to characterise a natural disturbance regime in a European temperate swamp forest dominated by Alnus glutinosa. Individual-based population genetic simulations were carried out for three previously introduced models of disturbance regime, to determine which best fits the FSGS assessed by the kinship coefficient in a natural old-growth forest. We hypothesised a low proportion of trees removed (the gap dynamic model) accentuates high-relatedness among individuals over short distances (i.e. it accentuates FSGS), while a high proportion of trees eliminated by a disturbance (the cyclic succession model and the stand-replacing dynamic model) leads either to random FSGS (i.e. a point pattern of genotypes that cannot be differentiated from a complete spatial randomness) or a high spatial clustering of genotypes. Spatial genetic analyses found significant positive autocorrelations of genotypes at < 30 m in the natural old-growth forest, which indicates A. glutinosa individuals were more highly clustered than for a null model with complete spatial randomness. However, the strength of FSGS was low as indicated by a kinship coefficient < 0.02. Comparing the FSGSs of simulated disturbance regimes with the FSGS recorded in the old-growth forest, the gap dynamic model was the most probable scenario, with small canopy gaps occurring continually through time. The cyclic succession model and the stand-replacing dynamic model also led to non-random FSGSs but in both these models, the FSGS was stronger and more coarse-grained than that observed. The approach of comparing the FSGS recorded in a natural forest with simulations of disturbance regimes allows support to be found for (or against) previously hypothesised disturbance patterns. This approach should be considered alongside the well-established dendrochronological and palaeoecological methods.

PATH-48. THE DNA METHYLATION LANDSCAPE OF CORE AND PERIPHERAL DIFFUSE GLIOMA REGIONS SHOWS LITTLE SPATIAL SUBTYPE HETEROGENEITY AFTER CONSIDERING TUMOR PURITY

Abstract While diffuse gliomas are notorious for their histopathological, genetic and transcriptional spatial heterogeneity, little is known about their epigenetic spatial heterogeneity. The result of spatial (epi)genetic analysis is strongly influenced by the proportion of cancer cells in a sample, so called tumor purity. However, a gold standard for assessment of tumor purity is lacking. We set out to analyze tumor purity using different measurement modalities and explore tumor purity-corrected DNA methylation spatial heterogeneity in glioma. DNA methylation(-derived), quantitative histological and radiological measurements of tumor purity, as well as DNA methylation profiles, were analyzed in 133 image-guided multi-sector stereotactic biopsy samples of 16 patients with newly diagnosed glioma. These biopsies were acquired in regions with and without abnormalities on MRI. Data was validated in two independent populations of respectively 102 multi-region samples in 24 glioma patients and 64 single-region samples from patients without glioma. DNA methylation profiles from The Cancer Genome Atlas and the patients without glioma was used to predict DNA methylation and transcriptional subtype. Consensus measurement of tumor purity estimates (CPE) ranged from 0 to 91% and was most correlated with the DNA methylation measurement of tumor purity. Neuropathological qualitative assessment of tumor presence generally corresponded well with CPE, but occasionally samples reported as ‘histologically normal’ demonstrated tumor purities up to 53%. After filtering specimens with tumor purity less than 50%, DNA methylation subtype showed little spatial heterogeneity, this in contrast to transcriptional subtype. Samples from core and peripheral regions showed similar DNA methylation profiles. Non-purity related intratumoral heterogeneity for promotor methylation of epigenetically regulated genes was minimal, but higher in IDH-wildtype than in IDH-mutant gliomas. In conclusion, after considering DNA methylation-based measurement of tumor purity DNA methylation in diffuse gliomas shows little spatial heterogeneity; incorporating such tumor purity information can further increase the reliability of methylation-profiling-based tumor classification.