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Distance Matrices (distance + matrix)
Selected AbstractsCombining spatial and phylogenetic eigenvector filtering in trait analysisGLOBAL ECOLOGY, Issue 6 2009Ingolf Kühn ABSTRACT Aim, To analyse the effects of simultaneously using spatial and phylogenetic information in removing spatial autocorrelation of residuals within a multiple regression framework of trait analysis. Location, Switzerland, Europe. Methods, We used an eigenvector filtering approach to analyse the relationship between spatial distribution of a trait (flowering phenology) and environmental covariates in a multiple regression framework. Eigenvector filters were calculated from ordinations of distance matrices. Distance matrices were either based on pure spatial information, pure phylogenetic information or spatially structured phylogenetic information. In the multiple regression, those filters were selected which best reduced Moran's I coefficient of residual autocorrelation. These were added as covariates to a regression model of environmental variables explaining trait distribution. Results, The simultaneous provision of spatial and phylogenetic information was effectively able to remove residual autocorrelation in the analysis. Adding phylogenetic information was superior to adding purely spatial information. Applying filters showed altered results, i.e. different environmental predictors were seen to be significant. Nevertheless, mean annual temperature and calcareous substrate remained the most important predictors to explain the onset of flowering in Switzerland; namely, the warmer the temperature and the more calcareous the substrate, the earlier the onset of flowering. A sequential approach, i.e. first removing the phylogenetic signal from traits and then applying a spatial analysis, did not provide more information or yield less autocorrelation than simple or purely spatial models. Main conclusions, The combination of spatial and spatio-phylogenetic information is recommended in the analysis of trait distribution data in a multiple regression framework. This approach is an efficient means for reducing residual autocorrelation and for testing the robustness of results, including the indication of incomplete parameterizations, and can facilitate ecological interpretation. [source] Not everything is everywhere: the distance decay of similarity in a marine host,parasite systemJOURNAL OF BIOGEOGRAPHY, Issue 2 2009Ana Pérez-del-Olmo Abstract Aim, We test the similarity,distance decay hypothesis on a marine host,parasite system, inferring the relationships from abundance data gathered at the lowest scale of parasite community organization (i.e. that of the individual host). Location, Twenty-two seasonal samples of the bogue Boops boops (Teleostei: Sparidae) were collected at seven localities along a coastal positional gradient from the northern North-East Atlantic to the northern Mediterranean coast of Spain. Methods, We used our own, taxonomically consistent, data on parasite communities. The variations in parasite composition and structure with geographical and regional distance were examined at two spatial scales, namely local parasite faunas and component communities, using both presence,absence (neighbour joining distance) and abundance (Mahalanobis distance) data. The influence of geographical and regional distance on faunal/community divergence was assessed through the permutation of distance matrices. Results, Our results revealed that: (1) geographical and regional distances do not affect the species composition in the system under study at the higher scales; (2) geographical distance between localities contributes significantly to the decay of similarity estimated from parasite abundance at the lowest scale (i.e. the individual host); (3) the structured spatial patterns are consistent in time but not across seasons; and (4) a restricted clade of species (the ,core' species of the bogue parasite fauna) contributes substantially to the observed patterns of both community homogenization and differentiation owing to the strong relationship between local abundance and regional distribution of species. Main conclusions, The main factors that tend to homogenize the composition of parasite communities of bogue at higher regional scales are related to the dispersal of parasite colonizers across host populations, which we denote as horizontal neighbourhood colonization. In contrast, the spatial structure detectable in quantitative comparisons only, is related to a vertical neighbourhood colonization associated with larval dispersal on a local level. The stronger decline with distance in the spatial synchrony of the assemblages of the ,core' species indicates a close-echoing environmental synchrony that declines with distance. Our results emphasize the importance of the parasite supracommunity (i.e. parasites that exploit all hosts in the ecosystem) to the decay of similarity with distance. [source] Importance of soils, topography and geographic distance in structuring central Amazonian tree communitiesJOURNAL OF VEGETATION SCIENCE, Issue 6 2008Stephanie A. Bohlman Abstract Question: What is the relative contribution of geographic distance, soil and topographic variables in determining the community floristic patterns and individual tree species abundances in the nutrient-poor soils of central Amazonia? Location: Central Amazonia near Manaus, Brazil. Methods: Our analysis was based on data for 1105 tree species (, 10 cm dbh) within 40 1-ha plots over a ca. 1000-km2 area. Slope and 26 soil-surface parameters were measured for each plot. A main soil-fertility gradient (encompassing soil texture, cation content, nitrogen and carbon) and five other uncorrelated soil and topographic variables were used as potential predictors of plant-community composition. Mantel tests and multiple regressions on distance matrices were used to detect relationships at the community level, and ordinary least square (OLS) and conditional autoregressive (CAR) models were used to detect relationships for individual species abundances. Results: Floristic similarity declined rapidly with distance over small spatial scales (0,5 km), but remained constant (ca. 44%) over distances of 5 to 30 km, which indicates lower beta diversity than in western Amazonian forests. Distance explained 1/3 to 1/2 more variance in floristics measures than environmental variables. Community composition was most strongly related to the main soil-fertility gradient and C:N ratio. The main fertility gradient and pH had the greatest impact of species abundances. About 30% of individual tree species were significantly related to one or more soil/topographic parameters. Conclusions: Geographic distance and the main fertility gradient are the best predictors of community floristic composition, but other soil variables, particularly C:N ratio, pH, and slope, have strong relationships with a significant portion of the tree community. [source] Comparison of T-RFLP and DGGE techniques to assess denitrifier community composition in soilLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2009K. Enwall Abstract Terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) and subsequent statistical analysis were compared with assess denitrifier community composition in agricultural soil based on the nosZ gene, encoding the nitrous oxide reductase. Analysis of binary or relative abundance-based metric and semi-metric distance matrices provided similar results for DGGE, but not for T-RFLP. Moreover, DGGE had a higher resolution than T-RFLP and binary data was better for discriminating between samples. [source] RAPD variation and population genetic structure in Prunus mahaleb (Rosaceae), an animal-dispersed treeMOLECULAR ECOLOGY, Issue 9 2000Pedro Jordano Abstract We examined the patterns of random amplified polymorphic DNA (RAPD) variation among seven Prunus mahaleb (Rosaceae) populations extending over , 100 km2 to examine local differentiation in relation to spatial isolation due to both geographical distance and differences in elevation. No less than 51.4% of the RAPD loci were polymorphic, but very few were fixed and among-population variation accounted for 16.46% of variation in RAPD patterns. Mean gene diversity was 0.1441, with mean Nei's genetic diversity for individual populations ranging between 0.089 and 0.149. Mean GST value across loci was 0.1935 (range, 0.0162,0.4685), giving an average estimate for Nm of 1.191. These results suggest extensive gene flow among populations, but higher GST and lower Nm values relative to other outcrossing, woody species with endozoochorous dispersal, also suggest a process of isolation by distance. The combined effect of both geographical and elevation distances and nonoverlapping flowering and fruiting phenophases on the GST matrix was partially significant, revealing only marginal isolation of the P. mahaleb populations. The matrix correlation between estimated Nm values among populations and the geographical + elevation distance matrices (r = ,0.4623, P = 0.07), suggests a marginal trend for more isolated populations to exchange less immigrants. Long-distance seed dispersal by efficient medium-sized frugivorous birds and mammals is most likely associated to the high levels of within-population genetic diversity. However, vicariance factors and demographic bottlenecks (high postdispersal seed and seedling mortality) explain comparatively high levels of local differentiation. [source] Social distance in Bosnia-Herzegovina and the North Caucasus region of Russia: Inter and intra-ethnic attitudes and identities,NATIONS AND NATIONALISM, Issue 2 2009KRISTIN M. BAKKE ABSTRACT. This article examines attitudinal differences and similarities among ethnic groups in conflict-affected societies. Conventional wisdom tells us that societies that have experienced violent struggles in which individuals of different ethnic groups have (been) mobilized against each other are likely to become polarized along ethnic lines. Indeed, both policy-makers and scholars often assume that such divisions are some of the main challenges that must be overcome to restore peace after war. We comparatively examine this conventional wisdom by mapping dimensions of social distance among 4,000 survey respondents in Bosnia-Herzegovina and the North Caucasus region of Russia. The surveys were carried out in December 2005. Using multidimensional scaling methods, we do not find patterns of clear attitudinal cleavages among members of different ethnic groups in Bosnia-Herzegovina. Nor do we find patterns of clear ethnic division in the North Caucasus, although our social distance matrices reveal a difference between Russians and ethnic minority groups. [source] Variation at 10 protein coding loci in the mbenzele pygmies from the central african republic and a comparison with microsatellite dataAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2002Valentina Coia Ten protein coding loci (6-PGD, A1-AT, ACP1, CaII, ESD, GC, GPX1, Hb,, PGM1, and TF) were analyzed in the Mbenzele Pygmies from the Central African Republic. The frequency data were used to calculate the genetic distances between Mbenzele Pygmies and other African groups. In the principal coordinate plot of FST genetic distances, the Mbenzele cluster together with other Pygmies of the western cluster, the Biaka from C.A.R., Gielli from Cameroon, and Babinga from Congo. By contrast, they are considerably distanced from other Pygmy groups of the eastern cluster (Twa from Rwanda, Mbuti from Zaire). Genetic distances obtained using protein loci were compared with those based on microsatellite loci. The two distance matrices are insignificantly correlated (r = 0.268; one tail probability = 0.332), and the main difference is in the higher genetic affinity between the Mbenzele and Biaka Pygmies observed at the protein level. Although reasons underlying the discrepancy between inter-populational variation at protein and DNA loci are not established with certainty, the comparison suggests that the genetic distance between the Mbenzele and Biaka Pygmies at microsatellite loci could have been shaped by genetic drift. Am. J. Hum. Biol. 14:9,14, 2002.© 2002 Wiley-Liss, Inc. [source] Genetic relationships between South African wheat cultivars as measured by gliadin banding patternsPLANT BREEDING, Issue 3 2000M. T. Labuschagne Abstract The use of gliadins in cultivar identification is a well-known practice that is used in many countries. The aim of this study was to determine the gliadin banding patterns of 35 commercial South African wheat cultivars and to use these data to determine genetic relationships between the cultivars using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The index of genetic similarity was used to calculate pairwise distance matrices, which were converted to a dendogram. Most of the gliadin bands fell within the nomenclature used. Fourteen cultivars had one novel band and six had two novel bands. All the cultivars could be distinguished from one another. Genetic distances between clusters were small. This suggested that there was not enough unique genetic variability to set any cluster apart from the others. [source] Three social distance measures for film rankingsPROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2003Gregory H. Leazer We describe the use of three alternative methods for ranking films for information retrieval (IR). A large film-person incidence matrix is generated using the principle cast, directors, producers and screenwriters for each film. These attributes are used to measure film-film distances by creating a distance matrix: two films are considered to be adjacent if there is any overlap in the people associated with each film. The distance between any two films is measured by the shortest path used to connect them through their adjacent members. The second and third methods involve the creation of a similarity matrix that expresses the amount of overlap in the people associated with any two films using Dice's coefficient. A "product distance" matrix is then derived that express the distances between any two films based on the product of the similarity weights on a path that connects those films. The highest value is chosen when alternate paths connect the two films. We also describe an "accumulative difference distance" matrix that also expresses the distances among pairs of films. The distance, product distance and accumulative difference distance matrices are used to generate rankings for a random sample of films. [source] Population-specific deviations of global human craniometric variation from a neutral modelAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010John H. Relethford Abstract Past studies have revealed that much of human craniometric variation follows a neutral model of population relationships. At the same time, there is evidence for the influence of natural selection in having shaped some global diversity in craniometrics. In order to partition these effects, and to explore other potential population-specific influences, this article analyzes residuals of craniometric distances from a geographically based neutral model of population structure. W.W. Howells' global craniometric data set was used for these analyses, consisting of 57 measurements for 22 populations around the world, excluding Polynesia and Micronesia because of the relatively recent settlement of these regions. Phenotypic and geographic distances were derived between all pairs of populations. Three-dimensional multidimensional scaling configurations were obtained for both distance matrices, and compared using a Procrustes rotation method to show which populations do not fit the geographic model. This analysis revealed three major deviations: the Buriat, Greenland Inuit, and Peru. The deviations of the Buriat and Greenland Inuit appear to be related to long-term adaptation to cold environments. The Peruvian sample is more similar to other New World populations than expected based on geographic distance alone. This deviation likely reflects the evolutionarily recent movement of human populations into South America, such that these populations are further from genetic equilibrium. This same pattern is seen in South American populations in a comparative analysis of classical genetic markers, but not in a comparative analysis of STR loci, perhaps reflecting the higher mutation rate for the latter. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] A genetic algorithm for the identification of conformationally invariant regions in protein moleculesACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2002Thomas R. Schneider Understanding macromolecular function often relies on the comparison of different structural models of a molecule. In such a comparative analysis, the identification of the part of the molecule that is conformationally invariant with respect to a set of conformers is a critical step, as the corresponding subset of atoms constitutes the reference for subsequent analysis for example by least-squares superposition. A method is presented that categorizes atoms in a molecule as either conformationally invariant or flexible by automatic analysis of an ensemble of conformers (e.g. crystal structures from different crystal forms or molecules related by non-crystallographic symmetry). Different levels of coordinate precision, both for different models and for individual atoms, are taken explicitly into account via a modified form of Cruickshank's DPI [Cruickshank (1999), Acta Cryst. D55, 583,601] and are propagated into error-scaled difference distance matrices [Schneider (2000), Acta Cryst. D56, 715,721]. All pairwise error-scaled difference distance matrices are then analysed simultaneously using a genetic algorithm. The algorithm has been tested on several well known examples and has been found to converge rapidly to reasonable results using a standard set of parameters. In addition to the description of the algorithm, a criterion is suggested for testing the identity of two three-dimensional models within experimental error without any explicit superposition. [source] Distance Decay of Tree Species Similarity in Protected Areas on Terra Firme Forests in Colombian AmazoniaBIOTROPICA, Issue 5 2009Álvaro Duque ABSTRACT In this study, we investigated the pattern of floristic similarity as a function of geographical distances and environmental variability in well-drained uplands (terra firme) in Colombian Amazonia. The study site comprised three National Natural Parks, Tinigua, Chiribiquete, and Amacayacu, located in different geological units that represent a soil fertility gradient linked to parental materials. Differences in species richness between sites were compared using rarefaction analysis. A clear floristic transition appeared in the east,west direction following a soil fertility gradient along the first PCoA axis. In multiple regression analyses based on distance matrices, both geographical distances and geology explained 64 percent of the total floristic variation. Geographical distances alone accounted for 12 percent of variation in floristic similarities among plots, while geology alone accounted for 1 percent, and the joint effect of both explained 51 percent of the floristic variation. The species richness trend supports the existence of a latitudinal corridor southward of the geographical Equator in the Amazon basin, where tree diversity reaches the maximum expected values. A coupled effect of stochastic dispersal limitation and habitat specialization would certainly appear to be an appropriate explanation for tree species turnover in terra firme forests in Colombian Amazonia, strongly emphasizing that competition and neutrality must be supplementary rather than mutually exclusive processes. This result pinpoints the effect of dispersal on floral mixing as an ongoing active process for structuring tree communities in NW Amazonia, and the size of the reserves as a relevant issue to protect rare species from extinction by chance. [source] Selective sampling for approximate clustering of very large data setsINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2008Liang Wang A key challenge in pattern recognition is how to scale the computational efficiency of clustering algorithms on large data sets. The extension of non-Euclidean relational fuzzy c-means (NERF) clustering to very large (VL = unloadable) relational data is called the extended NERF (eNERF) clustering algorithm, which comprises four phases: (i) finding distinguished features that monitor progressive sampling; (ii) progressively sampling from a N × N relational matrix RN to obtain a n × n sample matrix Rn; (iii) clustering Rn with literal NERF; and (iv) extending the clusters in Rn to the remainder of the relational data. Previously published examples on several fairly small data sets suggest that eNERF is feasible for truly large data sets. However, it seems that phases (i) and (ii), i.e., finding Rn, are not very practical because the sample size n often turns out to be roughly 50% of n, and this over-sampling defeats the whole purpose of eNERF. In this paper, we examine the performance of the sampling scheme of eNERF with respect to different parameters. We propose a modified sampling scheme for use with eNERF that combines simple random sampling with (parts of) the sampling procedures used by eNERF and a related algorithm sVAT (scalable visual assessment of clustering tendency). We demonstrate that our modified sampling scheme can eliminate over-sampling of the original progressive sampling scheme, thus enabling the processing of truly VL data. Numerical experiments on a distance matrix of a set of 3,000,000 vectors drawn from a mixture of 5 bivariate normal distributions demonstrate the feasibility and effectiveness of the proposed sampling method. We also find that actually running eNERF on a data set of this size is very costly in terms of computation time. Thus, our results demonstrate that further modification of eNERF, especially the extension stage, will be needed before it is truly practical for VL data. © 2008 Wiley Periodicals, Inc. [source] A diagonal measure and a local distance matrix to display relations between objects and variables,JOURNAL OF CHEMOMETRICS, Issue 1 2010Gergely Tóth Abstract Proper permutation of data matrix rows and columns may result in plots showing striking information on the objects and variables under investigation. To control the permutation first, a diagonal matrix measureD was defined expressing the size relations of the matrix elements. D is essentially the absolute norm of a matrix where the matrix elements are weighted by their distance to the matrix diagonal. Changing the order of rows and columns increases or decreases D. Monte Carlo technique was used to achieve maximum D in the case of the object distance matrix or even minimal D in the case of the variable correlation matrix to get similar objects or variables close together. Secondly, a local distance matrix was defined, where an element reflects the distances of neighboring objects in a limited subspace of the variables. Due to the maximization of D in the local distance matrix by row and column changes of the original data matrix, the similar objects were arranged close to each other and simultaneously the variables responsible for their similarity were collected close to the diagonal part defined by these objects. This combination of the diagonal measure and the local distance matrix seems to be an efficient tool in the exploration of hidden similarities of a data matrix. Copyright © 2009 John Wiley & Sons, Ltd. [source] A novel semi-empirical topological descriptor Nt and the application to study on QSPR/QSARJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2007Congyi Zhou Abstract A novel semi-empirical topological descriptor Nt was proposed by revising the traditional distance matrix based on the equilibrium electronegativity and the relative bond length. Nt can not only efficiently distinguish structures of organic compounds containing multiple bonds and/or heteroatoms, but also possess good applications of QSPR/QSAR (quantitative structure-property/activity relationships) to a large diverse set of compounds, which are alkanes, alkenes, alkynes, aldehydes, ketones, thiols, and alkoxy silicon chlorides with all the correlation coefficients of the models over 0.99. The LOO CV (leave-one-out cross-validation) method was used to testify the stability and predictive ability of the models. The validation results verify the good stability and predictive ability of the models employing the cross-validation parameters: RCV, SEPCV and SCV, which demonstrate the wide potential of the Nt descriptor for applications to QSPR/ QSAR. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] Evolutionary Relationships of the Dutch Elm Disease Fungus Ophiostoma novo-ulmi to Other Ophiostoma Species Investigated by Restriction Fragment Length Polymorphism Analysis of the rDNA RegionJOURNAL OF PHYTOPATHOLOGY, Issue 9-10 2000N. D. Pipe Restriction fragment length polymorphisms (RFLPs) in the ribosomal RNA gene (rDNA) region were used to assess relationships between the Dutch elm disease fungi Ophiostoma novo-ulmi and Ophiostoma ulmi, the recently described Himalayan Dutch elm disease pathogen, Ophiostoma himal-ulmi, the morphologically similar sapstain fungi, Ophiostoma piceae and Ophiostoma quercus, and several Ophiostoma species from hardwood trees, including Ophiostoma stenoceras and Ophiostoma proliferum. A distance matrix and cluster analysis indicated that the rDNA region of O. himal-ulmi is more closely related to those of O. novo-ulmi and O. ulmi than to those of O. piceae and O. quercus and is more distantly related to O. stenoceras and the other Ophiostoma species, which formed a separate clade. The rDNA region of O. quercus was found to be at least as closely related to that of O. novo-ulmi and O. ulmi as it is to that of O. piceae. The implications of these results for the evolution of the Dutch elm disease fungi are discussed. [source] Detection and visualization of spatial genetic structure in continuous Eucalyptus globulus forestMOLECULAR ECOLOGY, Issue 4 2007TIM H. JONES Abstract Visualizing the pattern of variation using microsatellites within a Eucalyptus globulus forest on the island of Tasmania provided surprising insights into the complex nature of the fine-scale spatial genetic structure that resides in these forests. We used spatial autocorrelation and principal coordinate analysis to compare fine-scale genetic structure between juvenile and mature cohorts in a study area, 140 m in diameter, located within a typical, continuous E. globulus forest. In total, 115 juvenile and 168 mature individuals were genotyped with eight highly polymorphic microsatellite loci. There was no significant difference in the level of genetic diversity between cohorts. However, there were differences in the spatial distribution of the genetic variation. Autocorrelation analysis provided clear evidence for significant spatial genetic structure in the mature cohort and significant, but weaker, structure in the juvenile cohort. The spatial interpolation of principal coordinate axes, derived from ordination of the genetic distance matrix between individuals, revealed a spatially coherent family group which was evident in both cohorts. Direct comparison of the genetic structure within each cohort allowed visualization of a shift in the spatial distribution of genetic variation within the population of approximately 10 m. As the shift coincided with the direction of prevailing winds, it is hypothesized that this phenomenon is due to downwind dispersal of seeds and is indicative of the important role of prevailing winds in forcing eastward gene flow in these high-latitude forests. [source] Comparison of genetic diversity estimates within and among populations of maritime pine using chloroplast simple-sequence repeat and amplified fragment length polymorphism dataMOLECULAR ECOLOGY, Issue 5 2002M. M. Ribeiro Abstract We compared the genetic variation of Pinus pinaster populations using amplified fragment length polymorphism (AFLP) and chloroplast simple-sequence repeat (cpSSR) loci. Populations' levels of diversity within groups were found to be similar with AFLPs, but not with cpSSRs. The high interlocus variance associated with the AFLP loci could account for the lack of differences in the former. Although AFLPs revealed much lower genetic diversity than cpSSRs, the levels of among-population differentiation found with the two types of marker were similar, provided that loci showing fewer than four null-homozygotes, in any population, were pruned from the AFLP data. Moreover, the French and Portuguese populations were clearly differentiated from each other, with both markers. The Mantel test showed that the genetic distance matrix calculated using the AFLP data was correlated with the matrix derived from the cpSSRs. Because of the concordance found between markers we conclude that gene flow was indeed the predominant force shaping nuclear and chloroplastic genetic variation of the populations within regions, at the geographical scale studied. [source] Origin of Fueguian-Patagonians: An approach to population history and structure using R matrix and matrix permutation methodsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2002Rolando González José A complicated history of isolation between Fueguian and Patagonian groups (originated by the appearance of the Straits of Magellan) as much as differences in population structure and life strategies constitute important factors in the clustering pattern of those groups. The aim of this work was to test several hypotheses about population structure and history of Fueguian-Patagonians to propose a model that incorporates predictions for future studies. R matrix methods and matrix permutation analyses were performed upon a data matrix of craniofacial measurements of 441 skulls divided into nine samples pertaining to six Patagonian and three Fueguian populations. Association of biological distances with three matrices representing several settlement patterns was tested using matrix permutation tests. Results of R matrix study show that the minimum genetic distance obtained confirms separation between Fueguians and Patagonians. Moreover, an analysis of residual variances from the expected regression line confirms admixture between Andean and Pampean populations and Araucanian groups, consistent with ethnohistorical observations. A model representing a long history of isolation between Fueguian and Patagonians, rather than a model emphasizing differences in life-strategies, presented the best correlation with the biological distance matrix. Because similar results were already obtained in archaeological, molecular, and morphological studies, a model for the settlement of Tierra del Fuego is proposed. It is summarized by four main hypotheses that can be tested independently by different disciplines in the future. Am. J. Hum. Biol. 14:308,320, 2002. © 2002 Wiley-Liss, Inc. [source] Three social distance measures for film rankingsPROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2003Gregory H. Leazer We describe the use of three alternative methods for ranking films for information retrieval (IR). A large film-person incidence matrix is generated using the principle cast, directors, producers and screenwriters for each film. These attributes are used to measure film-film distances by creating a distance matrix: two films are considered to be adjacent if there is any overlap in the people associated with each film. The distance between any two films is measured by the shortest path used to connect them through their adjacent members. The second and third methods involve the creation of a similarity matrix that expresses the amount of overlap in the people associated with any two films using Dice's coefficient. A "product distance" matrix is then derived that express the distances between any two films based on the product of the similarity weights on a path that connects those films. The highest value is chosen when alternate paths connect the two films. We also describe an "accumulative difference distance" matrix that also expresses the distances among pairs of films. The distance, product distance and accumulative difference distance matrices are used to generate rankings for a random sample of films. [source] Surnames in Siberia: A study of the population of Yakutia through isonymyAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009L. Tarskaia Abstract We studied the isonymic structure of the Republic of Sakha (Yakutia), in the Russian Federation, using the surname distributions of 491,259 citizens above 18 years registered as residents in 2002. These were distributed in 35 districts and 497 towns and settlements of the Republic. The number of different surnames was 44,625. Matrices of isonymic distances between the 35 districts were tested for correlation with the geographic distance between the population centers of gravity of thedistricts. We found that, for the whole of Yakutia, Nei's distance was correlated with geographic distance (r = 0.693 ± 0.027). A dendrogram of the 35 districts was built from the distance matrix, using the UPGMA method. The clusters identified by the dendrogram correlate with the geographic position of the districts. The correlation of random inbreeding calculated from isonymy, FST, with latitude was positive and highly significant but weak (r = 0.23). So, inbreeding was highest in the Arctic districts, and lowest in the South. Average , for 497 towns was 107, for 35 districts it was 311, and for the Republic 433. The value of , was higher for Russian than for the local languages. The geographical distribution of ,, high in the Center and South-East and lower in the North-West, is compatible with the settlement of groups of migrants moving from the South-East toward the center and the North of Yakutia. It is proposed that low-density demic diffusion of human populations results in high inbreeding and may have been a general phenomenon in the early phases of human radiations. Am J Phys Anthropol 2009. © 2008 Wiley-Liss, Inc. [source] Genetic differentiation among the Maculinea species (Lepidoptera: Lycaenidae) in eastern Central EuropeBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2007KATALIN PECSENYE The present study aimed to analyse the level of genetic variation in the eastern Central European (Slovenia, Hungary, and Romania/Transylvania) populations of the Large Blues (Maculinea) to analyse the pattern of differentiation both between and within the species. One objective was to compare the level of differentiation between the two disputed species (Maculinea alcon and Maculinea rebeli) with that among the other species. Imagos were collected from 23 localities in eastern Central Europe in 2002. Enzyme polymorphism was analysed using polyacrylamide gel electrophoresis. Fourteen enzyme loci were studied in all samples. In the analysis of the data, F -statistics and Nei's genetic distances were calculated and a dendrogram (unweighted pair group method with arithmetic mean) was constructed on the basis of the distance matrix. A multivariate analysis of variance was performed to study the pattern of genetic differentiation among the samples. Principal component analysis analysis was also carried out using the allele frequency data of the samples. Our results indicated that the large blues are generally less polymorphic than other European lycaenid butterflies studied. At the same time, the level of genetic differentiation was high, even among local populations within the species. A low level of genetic variation within the populations coupled with strong differentiation among them implies the effect of genetic drift. Strong genetic differentiation of four Maculinea species (M. alcon, Maculinea teleius, Maculinea nausithous, and Maculinea arion) was confirmed. Significant differentiation was not found between M. alcon and M. rebeli. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 11,21. [source] | ||||||||||||||||||||||||||||