@inbook{3564, author = {Edelsbrunner, Herbert}, booktitle = {Überblicke Informationsverarbeitung }, editor = {Maurer, Hermann}, isbn = {9783411016587}, pages = {55 -- 109}, publisher = {BI Wissenschaftsverlag}, title = {{Neue Entwicklungen im Bereich Datenstrukturen}}, year = {1983}, } @article{3598, author = {Barton, Nicholas H and Jones, Steve}, issn = {1476-4687}, journal = {Nature}, pages = {317 -- 318}, publisher = {Springer Nature}, title = {{Mitochondrial DNA: new clues about evolution}}, doi = {10.1038/306317a0}, volume = {306}, year = {1983}, } @article{3666, abstract = {We have made an extensive allozyme survey of 21 enzyme and protein loci in populations of the alpine grasshopper Podisma pedestris. This species occurs in two races, differing by a chromosomal fusion which separates the ancestral XO/XX race from a derived neo-XY race. These races also differ in DNA content, and hybrids between them have reduced viability. Electrophoresis reveals that the amount of genetic differentiation between these races is no greater than the variation among populations within each race. Both larger-scale surveys and a detailed survey of an area where the races hybridize, show that the chromosomal change is not correlated with gene frequency changes at any of the 21 loci studied. These findings are consistent with recently developed theory concerning the strength of the barrier to gene flow posed by a hybrid zone with characteristics such as those measured experimentally in Podisma. It is argued that hybrid zones in other species which involve allozymic differences do so because of stronger selection against hybrids rather than through mating isolation.}, author = {Halliday, Bruce and Barton, Nicholas H and Hewitt, Godfrey}, issn = {1095-8312}, journal = {Biological Journal of the Linnean Society}, keywords = {Hybrid zone, Electrophoresis, Podisma pedestris, Polymorphism}, number = {1}, pages = {51 -- 62}, publisher = {Oxford University Press}, title = {{Electrophoretic analysis of a chromosomal hybrid zone in the grasshopper Podisma pedestris}}, doi = {10.1111/j.1095-8312.1983.tb00776.x}, volume = {19}, year = {1983}, } @article{3667, abstract = {Populations of the grasshopper Podisma pedestris were collected from two ends of a zone of hybridization between two chromosome races, at Seyne and Tende in southern France. 21 enzyme and protein loci were detected by gel electrophoresis. Six of these loci showed widespread polymorphism, and a further eleven had very little or no variation. Two loci (Idh, 6Pgd) had rare alleles in different frequencies in the two areas surveyed. The remaining two loci (Mdh-1, Mdh-2) showed a marked increase in the frequency of rare variants, from 1 per cent outside the hybrid zone, up to 5 per cent at its centre. This region of increased electrophoretic variation coincided with the chromosomal cline between the two races, and with a region of decreased viability. It was spread over about the same width as the chromosomal cline. Possible explanations for this extra variation include intragenic recombination and elevated mutation rates.}, author = {Barton, Nicholas H and Halliday, Bruce and Hewitt, Godfrey}, issn = {1365-2540}, journal = {Heredity}, number = {2}, pages = {139 -- 146}, publisher = {Nature Publishing Group}, title = {{Rare electrophoretic variants in a hybrid zone}}, doi = {10.1038/hdy.1983.15}, volume = {50}, year = {1983}, } @article{3668, abstract = {When two populations which differ at many loci meet, the degree of introgression of alleles across the boundary will depend on the selection acting on each locus (s), the rate of recombination between adjacent loci (r), and the number of loci involved (n). Simple scaling arguments suggest that the behavior of the system should depend on the ratio of selection to recombination (θ = s/r), and on n. This is borne out by mathematical analysis of two demes which exchange individuals at a low rate; when selection is stronger than recombination (θ > 1), the effective selection on each locus is comparable to the total selection over the whole genome (s* ∼ ns). When selection is weaker than recombination (θ < 1), the effective selection is much weaker, but is still stronger than the selection on each locus alone (s* \sim sn20 for small θ). When n is very large, these two regimes are separated by a sharp threshold at θ = 1. The results are extended to two taxa which meet in a continuous habitat; the effective selection pressure, which determines the width of the hybrid zone, behaves in the same way as for the simpler case above. Even when selection is weak compared to recombination, multilocus clines have a sharp step at their center, flanked by tails of introgression in which the alleles behave independently of each other. The set of clines acts as a barrier to gene flow, and it is shown that the barrier is strongest when selection is spread over many loci. The implications of the results for divergence and speciation are discussed.}, author = {Barton, Nicholas H}, issn = {1558-5646}, journal = {Evolution; International Journal of Organic Evolution}, number = {3}, pages = {454 -- 471}, publisher = {Society for the Study of Evolution}, title = {{Multilocus clines}}, doi = {10.2307/2408260}, volume = {37}, year = {1983}, } @inproceedings{4124, author = {Edelsbrunner, Herbert and Welzl, Emo}, booktitle = {International Colloquium on Automata, Languages, and Programming}, keywords = {Voronoi diagram, Asymptotic bound, Straightforward counting, Affine trans, Neighbor Voronoi diagram}, location = {Barcelona, Spain}, pages = {182 -- 187}, publisher = {Springer}, title = {{On the number of equal-sized semispaces of a set of points in the plane}}, doi = {10.1007/BFb0036908}, volume = {154}, year = {1983}, } @article{4125, abstract = {Let S denote a set of n points in the plane such that each point p has assigned a positive weight w(p) which expresses its capability to influence its neighbourhood. In this sense, the weighted distance of an arbitrary point x from p is given by de(x,p)/w(p) where de denotes the Euclidean distance function. The weighted Voronoi diagram for S is a subdivision of the plane such that each point p in S is associated with a region consisting of all points x in the plane for which p is a weighted nearest point of S. An algorithm which constructs the weighted Voronoi diagram for S in O(n2) time is outlined in this paper. The method is optimal as the diagram can consist of Θ(n2) faces, edges and vertices. }, author = {Aurenhammer, Franz and Edelsbrunner, Herbert}, issn = {1873-5142}, journal = {Pattern Recognition}, number = {2}, pages = {251 -- 257}, publisher = {Elsevier}, title = {{An optimal algorithm for constructing the weighted Voronoi diagram in the plane}}, doi = {10.1016/0031-3203(84)90064-5}, volume = {17}, year = {1983}, } @article{4126, abstract = {Rectangle intersections involving rectilinearly-oriented (hyper-) rectangles in d-dimensional real space are examined from two points of view. First, a data structure is developed which is efficient in time and space and allows us to report all d-dimensional rectangles stored which intersect a d-dimensional query rectangle. Second, in Part II, a slightly modified version of this new data structure is applied to report all intersecting pairs of rectangles of a given set. This approach yields a solution which is optimal in time and space for planar rectangles and reasonable in higher dimensions.}, author = {Edelsbrunner, Herbert}, issn = {1029-0265}, journal = {International Journal of Computer Mathematics}, number = {3-4}, pages = {209 -- 219}, publisher = {Taylor & Francis}, title = {{A new approach to rectangle intersections part 1}}, doi = {10.1080/00207168308803364}, volume = {13}, year = {1983}, } @article{4127, abstract = {The study begun in Part I is completed by providing an algorithm which reports all intersecting pairs of a set of rectangles in d dimensions. This approach yields a solution which is optimal in time and space for planar rectangles and reasonable in higher dimensions.}, author = {Edelsbrunner, Herbert}, issn = {1029-0265}, journal = {International Journal of Computer Mathematics}, number = {3-4}, pages = {221 -- 229}, publisher = {Taylor & Francis}, title = {{A new approach to rectangle intersections part 2}}, doi = {10.1080/00207168308803365}, volume = {13}, year = {1983}, } @article{4128, abstract = {A generalization of the convex hull of a finite set of points in the plane is introduced and analyzed. This generalization leads to a family of straight-line graphs, " \alpha -shapes," which seem to capture the intuitive notions of "fine shape" and "crude shape" of point sets. It is shown that a-shapes are subgraphs of the closest point or furthest point Delaunay triangulation. Relying on this result an optimal O(n \log n) algorithm that constructs \alpha -shapes is developed.}, author = {Edelsbrunner, Herbert and Kirkpatrick, David and Seidel, Raimund}, issn = {1558-0814}, journal = {IEEE Transactions on Information Theory}, number = {4}, pages = {551 -- 559}, publisher = {IEEE}, title = {{On the shape of a set of points in the plane}}, doi = {10.1109/TIT.1983.1056714 }, volume = {29}, year = {1983}, } @inbook{4328, abstract = {The hybrid zone which forms when two partially incompatible populations meet acts as a barrier to gene flow. We discuss electrophoretic and theoretical evidence on the strength of such barriers. Hybrid zones generally involve considerable electrophoretic divergence. The enzyme clines are consistent in position and width; in some cases, they show consistently asymmetric patterns of introgression. This consistency suggests that the clines are maintained primarily by the indirect effects of selection at linked loci, rather than by the effect of each individual locus on fitness. A cline at a single locus will present some barrier, regardless of the selective mechanism which maintains it. However, unless the locus induces virtually complete assortment or hybrid unfitness, the barrier will be weak. Spreading the same selection over more clines gives a stronger barrier. If the clines are staggered, this barrier is still unlikely to be significant; if they coincide, and if selection is stronger than recombination, then the barrier will be very strong; its strength and asymmetry will be consistent over different loci. Thus, the taxonomic status of divergent populations cannot be inferred just from the total amount of pre- or post-mating isolation; the number of genetic differences, and the interactions between them are equally important in determining rates of gene flow.}, author = {Barton, Nicholas H and Hewitt, Godfrey}, booktitle = {Protein polymorphism: Adaptive and taxonomic significance}, editor = {Oxford, Geoffrey and Rollinson, David}, isbn = {978-0-1253-1780-1}, issn = {0309-2593}, keywords = {chemotaxonomy}, location = {University of York, United Kingdom}, pages = {341 -- 359}, publisher = {Academic Press}, title = {{Hybrid zones as barriers to gene flow}}, volume = {24}, year = {1983}, } @misc{4329, author = {Barton, Nicholas H}, booktitle = {Animal Behaviour}, issn = {1095-8282}, number = {2}, pages = {626 -- 627}, publisher = {Elsevier}, title = {{The extended phenotype: the gene as the unit of selection (review of Dawkins R 1982)}}, doi = {10.1016/S0003-3472(83)80100-6}, volume = {31}, year = {1983}, } @misc{4330, author = {Barton, Nicholas H}, booktitle = {Heredity}, issn = {1365-2540}, pages = {213 -- 213}, publisher = {Springer Nature}, title = {{Gene flow and speciation (abstract)}}, doi = {10.1038/hdy.1983.24}, volume = {50}, year = {1983}, } @article{3669, abstract = {The dispersal rate of the grasshopper Podisma pedestris has been measured, with the aim of interpreting the width of a chromosomal cline. 171 adults were marked individually, and released within the cline. 169 movements were seen over three subsequent scorings; the distribution of distances, after correction for the loss of long distance dispersants, was close to a normal curve, but there was an initial shift of ten metres, perhaps towards a better habitat. The linear variance increased at about 214 m2 day- 1, which corresponds to a standard deviation of 207 m gen- 1/2 over a 20 day life span. Statistical uncertainty in this estimate can be expressed using a distribution-free maximum likelihood method, which gives support limits of 186- 270 m gen- 1/2. However, the main errors come from extrapolating from this experiment to the cline as a whole.}, author = {Barton, Nicholas H and Hewitt, Godfrey}, issn = {1365-2540}, journal = {Heredity}, number = {2}, pages = {237 -- 249}, publisher = {Springer Nature}, title = {{A measurement of dispersal in the grasshopper Podisma pedestris (Orthoptera: Acrididae)}}, doi = {10.1038/hdy.1982.29}, volume = {48}, year = {1982}, } @article{4129, abstract = {An algorithm for the geometric problem of determining a line (called a stabbing line) which intersects each ofn given line segments in the plane is presented. As a matter of fact, the algorithm computes a description of all stabbing lines. A purely geometric fact is proved which infers that this description requiresO(n) space to be specified. Our algorithm computes it inO(n logn) time which is optimal in the worst case. Using the description of the stabbing lines, we are able to decide inO(logn) time whether or not a specified line is a stabbing line. Finally, the problem of maintaining the description of all stabbing lines while inserting and deleting line segments is addressed.}, author = {Edelsbrunner, Herbert and Maurer, Hermann and Preparata, Franco and Rosenberg, Arnold and Welzl, Emo and Wood, Derick}, issn = {1572-9125}, journal = {BIT Numerical Mathematics}, number = {3}, pages = {274 -- 281}, publisher = {Springer Nature}, title = {{Stabbing line segments}}, doi = {10.1007/BF01934440}, volume = {22}, year = {1982}, } @article{4130, author = {Edelsbrunner, Herbert and Maurer, Hermann and Kirkpatrick, David}, issn = {1872-6119}, journal = {Information Processing Letters}, number = {2}, pages = {74 -- 79}, publisher = {Elsevier}, title = {{Polygonal intersection searching}}, doi = {10.1016/0020-0190(82)90090-4}, volume = {14}, year = {1982}, } @article{4131, author = {Edelsbrunner, Herbert and Overmars, Mark}, issn = {1872-6119}, journal = {Information Processing Letters}, number = {3}, pages = {124 -- 127}, publisher = {Elsevier}, title = {{On the equivalence of some rectangle problems}}, doi = {10.1016/0020-0190(82)90068-0}, volume = {14}, year = {1982}, } @article{4331, author = {Barton, Nicholas H}, issn = {1558-5646}, journal = {Evolution}, number = {4}, pages = {863 -- 866}, publisher = {Wiley}, title = {{The structure of the hybrid zone in Uroderma bilobatum (Chiroptera: Phyllostomatidae)}}, doi = {10.1111/j.1558-5646.1982.tb05452.x}, volume = {36}, year = {1982}, } @article{3670, abstract = {The grasshopper Podisma pedestris includes two chromosomal races, which differ by a Robertsonian fusion involving the sex chromosome. The two races meet in a cline which runs for 100 km across the Alpes Maritimes in south-eastern France. An intensive study of the easternmost end of this cline shows that it is about 800 m wide; the cline is not smooth, containing substantial spikes in chromosome frequency which might be due to sampling drift. Though the cline seems narrow, it is wide compared with the dispersal rate of the insect; a selective force of only 0.5% would be enough to maintain the cline. It is difficult to determine the nature of this force, but some evidence comes from the position of the cline, and from the presence of coincident clines at other loci. An estimate of the distribution of Podisma has been made, and the cline seems to follow, for the most part, a region of low population density, suggesting that it is maintained by hybrid unfitness. However, in the one region where the cline is relatively free to move, the XY race bulges forwards more than would be expected if hybrids are unfit. The observation of severe inviability in crosses between the races, though it is not associated with the chromosomal difference, also indicates that this cline is the result of some sort of genetic incompatibility.}, author = {Barton, Nicholas H and Hewitt, Godfrey}, issn = {1558-5646}, journal = {Evolution; International Journal of Organic Evolution}, number = {5}, pages = {1008 -- 1018}, publisher = {Wiley-Blackwell}, title = {{A chromosomal cline in the grasshopper Podisma pedestris}}, doi = { 10.1111/j.1558-5646.1981.tb04966.x}, volume = {35}, year = {1981}, } @article{3671, author = {Barton, Nicholas H}, issn = {1365-2540}, journal = {Heredity}, pages = {279 -- 282}, publisher = {Nature Publishing Group}, title = {{The width of the hybrid zone in Caledia captiva}}, doi = {10.1038/hdy.1981.86}, volume = {47}, year = {1981}, }