Neighbours

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Neighbours

  • nearest neighbour

  • Terms modified by Neighbours

  • neighbour distance
  • neighbour effects
  • neighbour interaction

  • Selected Abstracts


    Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

    JOURNAL OF BIOGEOGRAPHY, Issue 12 2007
    Patrik Mrz
    Abstract Aim, The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post-glacial history of many high-mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems , the Alps and the Carpathians. Location, Alps and Carpathians. Methods, The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results, Neighbour joining and principal coordinate analyses revealed three well-supported phylogeographical groups of populations corresponding to three disjunct geographical regions , the Alps and the western and south-eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within-population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region-diagnostic markers than those from the south-eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south-western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions, Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south-eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long-term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps. [source]


    A mitochondrial phylogeography of Brachidontes variabilis (Bivalvia: Mytilidae) reveals three cryptic species

    JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 4 2007
    M. Sirna Terranova
    Abstract This study examined genetic variation across the range of Brachidontes variabilis to produce a molecular phylogeography. Neighbour joining (NJ), minimum evolution (ME) and maximum parsimony (MP) trees based on partial mitochondrial DNA sequences of 16S-rDNA and cytochrome oxidase (COI) genes revealed three monophyletic clades: (1) Brachidontes pharaonis s.l. from the Mediterranean Sea and the Red Sea; (2) B. variabilis from the Indian Ocean; (3) B. variabilis from the western Pacific Ocean. Although the three clades have never been differentiated by malacologists employing conventional morphological keys, they should be ascribed to the taxonomic rank of species. The nucleotide divergences between Brachidontes lineages (between 10.3% and 23.2%) were substantially higher than the divergence between congeneric Mytilus species (2.3,6.7%) and corresponded to interspecific divergences found in other bivalvia, indicating that they should be considered three different species. Analysis of the 16S-rDNA sequences revealed heteroplasmy, indicating dual uniparental inheritance (DUI) of mtDNA in the species of Brachidontes collected in the Indian Ocean, but not in the species in the Pacific nor in the species in the Red Sea and the Mediterranean Sea. When we employed the conventional estimate of the rate of mitochondrial sequence divergence (2% per million years), the divergence times for the three monophyletic lineages were 6,11 Myr for the Indian Ocean and Pacific Ocean Brachidontes sp. and 6.5,9 Myr for the Red Sea and Indian Ocean Brachidontes sp. Thus, these species diverged from one another during the Miocene (23.8,5.3 Myr). We infer that a common ancestor of the three Brachidontes species probably had an Indo-Pacific distribution and that vicariance events, linked to Pleistocene glaciations first and then to the opening of the Red Sea, produced three monophyletic lineages. Riassunto Lo studio filogeografico stato condotto su tutto l'areale di Brachidontes variabilis (Krauss, 1848) attraverso l'analisi di sequenze mitocondriali (16S-rDNA e COI) che hanno separato i campioni in tre cladi monofiletici. Diversi algoritmi (NJ, ME e MP) hanno elaborato alberi con la stessa topologia, in cui possibile riconoscere: (1) Brachidontes pharaonis s.l. dell'area Mar Mediterraneo , Mar Rosso; (2) Brachidontes variabilis dell' Oceano Indiano; (3) Brachidontesvariabilis dell'Oceano Pacifico. Il loro grado di divergenza sufficientemente alto da potere ascrivere al rango di specie i singoli cladi, nonostante non siano stati ancora individuati i caratteri tassonomici distintivi, a causa della grande variazione morfologica. La divergenza nucleotidica tra le tre linee di Brachidontes era compresa tra 10.3% e 23.2%, in un range di valori superiori a quelli trovati nel confronto tra specie congeneriche di Mytilus sp (2.3,6.7%). Utilizzando il tasso evolutivo, che convenzionalmente viene applicato ai valori di divergenza genetica di geni mitocondriali (2% per milioni di anni), si sono ricavati tempi di divergenza corrispondenti a 6,11 milioni di anni tra Oceano Indiano e Pacifico, e a 6.5,9 milioni di anni tra Mar Rosso e Oceano Indiano. Le tre linee evolutive sembrano essersi separate durante il Miocene. Probabilmente un comune antenato con distribuzione Indo-Pacifica pu essere andato incontro a processi di vicarianza e/o di dispersione legati alle glaciazioni pleistoceniche prima e all'apertura del Mar Rosso dopo. [source]


    ,The Christian as Christ to the Neighbour': On Luther's Theology of Love

    INTERNATIONAL JOURNAL OF SYSTEMATIC THEOLOGY, Issue 2 2004
    Veli-Matti Krkkinen
    In outlining Luther's contrast between the love of God and the human loves, it is argued that Luther nonetheless is still able to value human love. Finally, the relationship between love and faith in Luther is described: love is chief among the many gifts of God that we receive by faith. [source]


    ANGOLA,DR CONGO: Throwing Out the Neighbours

    AFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 10 2009
    Article first published online: 27 NOV 200
    No abstract is available for this article. [source]


    Desire, demand and psychotherapy: on large groups and Neighbours

    PSYCHOTHERAPY AND POLITICS INTERNATIONAL, Issue 3 2008
    Stephen FroshArticle first published online: 24 SEP 200
    Abstract Explanations of the disturbing effects of large groups are sought in the group analytic literature, where there is an emphasis on boundary disturbance, and in contemporary psychoanalytic and social theory, where the peculiar nature of the ,neighbour' has become a topic for investigation. It is argued that the human subject is an ,interrupted' subject, with the other/neighbour being a key figure in creating this interruption. In large groups, the alien nature of the neighbour who is both close and unknowable comes to the fore, disrupting attempts to cover over this ,interruption' and promoting confusion and dislocation. The large group is consequently expressive of specific forms of contemporary sociality, and also suggestive for an ethical practice of psychotherapy that does not reduce to consolation. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Correlates of Self-Directed Behaviour in Wild White-Faced Capuchins

    ETHOLOGY, Issue 4 2000
    Joseph H. Manson
    Elevated rates of self-directed behaviour (SDB) such as self-scratching and autogrooming have been widely used in recent years as an indicator of anxiety in catarrhine primates. This study presents the first examination of correlates of SDB rates in a platyrrhine primate. Subjects were 8 wild female white-faced capuchins at Lomas Barbudal, Costa Rica, who were observed for 119 h of focal individual follows. The subjects performed significantly more self-scratching and autogrooming while in close proximity to conspecifics than while alone, irrespective of whether the neighbour was dominant or subordinate to them. This result was attributable to elevated SDB rates during the 30 s preceding and following allogrooming bouts. Furthermore, subjects engaged in more SDB while in proximity to females (a) that were closer to them in dominance rank and (b) with whom they spent a larger proportion of their time in proximity. Self-directed behaviour rates after conflicts did not differ from non-postconflict rates. Nor were SDB rates above baseline levels during the 30 s before subjects descended to the ground. These results may provide support for the view that SDB rates index anxiety in this species, if grooming decisions signal individuals' current allegiances and are therefore a source of anxiety, even if being groomed is, itself, relaxing. Postconflict preparation for further aggression may mitigate against scratching and autogrooming in a fast-moving arboreal species. [source]


    Relationship between presence of basidiomes, above-ground symptoms and root infection by Collybia fusipes in oaks

    FOREST PATHOLOGY, Issue 1 2000
    B. Maris
    Summary Collybia fusipes is a common cause of root rot on oak in the north of France. Collybia fusipes basidiomes can be as frequent on oaks in stands where no decline of the trees occurs compared with stands where the decline is chronic. This might be explained by differences in the amount of roots damaged by the parasite. To test that hypothesis, 430 oak trees, Quercus petraea, Quercus robur and Quercus rubra, located in six forests were selected. Half of them showed C. fusipes basidiomes at the trunk base. The association between presence of basidiomes and decline of affected trees depended on the forest. The level of infection of each tree by C. fusipes, as well as the crown appearance, the tree height : diameter at breast height ratio, age and sapwood width were determined. The presence of C. fusipes basidiomes was always associated with significant root infections. The crowns of the trees deteriorated with increasing level of root infection and the decline was severe only when the root damage was heavy. Although the decline of trees that were heavily damaged by C. fusipes was severe in some of the stands, in others, it was only mild, and so the differences in tree decline between the stands could not be attributed solely to differences in root infection severity. Trees damaged by C. fusipes seemed not to be subjected to more competition than their undamaged neighbour as reflected by a similar tree height: diameter at breast height ratio. [source]


    Phosphorus uptake, not carbon transfer, explains arbuscular mycorrhizal enhancement of Centaurea maculosa in the presence of native grassland species

    FUNCTIONAL ECOLOGY, Issue 6 2002
    C. A. Zabinski
    Summary 1Previous studies have shown that arbuscular mycorrhizas (AM) enhance the growth of the invasive forb Centaurea maculosa when growing with native grass species. Using 13CO2, we tested the hypothesis that this enhancement is explained by carbon transfer from native species to C. maculosa via mycorrhizal hyphal linkages. 2A C. maculosa plant was paired with one of five native species , three grasses (Festuca idahoensis, Koeleria cristata and Pseudoroegneria spicata) and two forbs (Achillea millefolium and Gaillardia aristata) , in pots that separated the plants with either a mesh barrier (28 m, excludes fine roots but not hyphae) or a membrane barrier (045 m, excludes roots and hyphae). 313CO2 was added to the atmosphere of either Centaurea or the native species after 20 weeks' growth. A 25 min pulse application was followed by 7 days' growth and subsequent harvest. 4The biomass response of C. maculosa was consistent with previous experiments: C. maculosa was larger when growing in mesh barrier pots, when hyphae were able to access the opposite side of the pot; in mesh barrier pots only, biomass varied with neighbouring species. Native plant biomass did not vary between mesh- vs membrane-barrier pots. 5There was no evidence of carbon transfer, either from the native plant to C. maculosa or in the reverse direction. 6Centaurea maculosa contained significantly more phosphorus in mesh-divided pots, but this depended on the neighbouring plant. The P concentration in C. maculosa was significantly higher in mesh-divided pots when growing with a grass and not a forb. Native species contained more P in mesh-divided pots than membrane-divided pots, and P concentration differed between species (higher in forbs than grasses), but did not vary between mesh- and membrane-divided pots. 7Our study suggests that C. maculosa is able to exploit its mycorrhizal symbiosis more effectively than the native grassland species. The mechanism for this appears to be luxury consumption of P through efficient utilization of extra-radical hyphae, but that effect is dependent on neighbouring species, and occurs when growing with a grass neighbour. 8Although no single study can disprove the carbon-transfer hypothesis, our work suggests that AM-mediated neighbour effects are the result of mycorrhizal networks that increase species' access to P. Whether the synergistic effects of neighbours are due to complementarity of AM fungal symbionts utilized by different plant species, or have to do with the structure of AM networks that develop more extensively with multiple host plants, remains to be investigated. [source]


    The capture and gratuitous disposal of resources by plants

    FUNCTIONAL ECOLOGY, Issue 1 2001
    Thomas H.
    Summary 1,Every plant will die if light, water or nutrients are withheld for long enough. It is natural to think of plants in general as having evolved a strong drive for resource acquisition as a survival mechanism. All else being equal, an individual that sequesters more material from the environment than its neighbour must be at a competitive advantage. 2,But the resource capture imperative seems at odds with the profligacy of some characteristic developmental and metabolic processes in many plants. Here, using leaf senescence as a vantage point, we consider whether a kind of wilful inefficiency of resource use may not be essential for success as a terrestrial autotroph. [source]


    Mechanical response of a jointed rock beam,numerical study of centrifuge models

    INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2007
    Michael Tsesarsky
    Abstract In this paper we present a comparison between a set of benchmark centrifuge models of a jointed beam and the predictions of two numerical models: fast Lagrangian analysis of continua (FLAC) and discontinuous deformation analysis (DDA). The primary objective of this paper is a comparison between the measured deformation profiles and thrust evolution to predictions of the numerical methods employed. A secondary objective is an attempt to clarify the issue of compressive arch geometry which is still in controversy among researchers. It is found that both FLAC and DDA result in insufficiently accurate predictions to the measured displacements. The mode of deformation is only partially captured and is dependent on the aspect ratio of the individual blocks which made up the beam. It is shown that the accuracy of the predicted displacements is a function of the assigned interface stiffness. The thrust predicted by both methods is found to be considerably lower than that measured in the model; however, the linear evolution of thrust and equilibrium conditions are correctly captured. The geometry of the compressive arch as predicted by FLAC compares extremely well with the data measured in the physical model. Based on the FLAC analysis it is found that for a beam composed of equidimensional blocks the thickness of the compressive arch varies from 0.8t at the abutment interface to the entire beam thickness (1t) at a distance of a half block width from the abutment face, extending across the interface separating the block and its neighbour, and attains a value of 0.5t at the beam mid span. Copyright 2006 John Wiley & Sons, Ltd. [source]


    Relay communications for Mars exploration

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2007
    Charles D. Edwards
    Telecommunication is an essential and challenging aspect of planetary exploration. For Mars landers, the constraints of mass, volume, power and energy typically limit their communications capabilities on the long-distance link back to Earth. By deploying relay spacecraft in Martian orbit, these landers can achieve much greater data return and can obtain contact opportunities at times when Earth is not in view. Currently, both NASA and European Space Agency (ESA) have pursued this strategy, deploying relay payloads on their Mars science orbiters. This relay infrastructure has significantly benefited the science return from the 2003 Mars Exploration Rovers and is poised to support the Phoenix Lander and Mars Science Laboratory missions later this decade. Longer-term plans call for continued growth in relay capability, greatly increasing data return from the Martian surface to enable exciting new Mars exploration concepts and advance our understanding of our planetary neighbour. Copyright 2007 John Wiley & Sons, Ltd. [source]


    Neighbour-stranger song discrimination in territorial ortolan bunting Emberiza hortulana males

    JOURNAL OF AVIAN BIOLOGY, Issue 4 2007
    Micha, Skierczynski
    Neighbour-stranger discrimination has been demonstrated in many species, but the mechanisms employed in discrimination vary. We tested whether an oscine bird with small repertoire size, the ortolan bunting Emberiza hortulana, discriminated between songs of neighbours and strangers. We performed playback experiments to measure response of males to a repeated single example of a single song type derived from a repertoire of a neighbour or stranger. Thirteen males were tested twice each, and in both cases songs were broadcast from the territory boundary shared by the subject male and the neighbour. Subjects responded more aggressively to songs of strangers than neighbours, i.e. they approached the loudspeaker faster and came closer and did more flights during the playback of stranger song. We found no significant differences in vocal response between treatments. We conclude that ortolan bunting can discriminate between songs of neighbours and strangers. This study provides experimental evidence for ortolan buntings in neighbour-stranger discrimination. It also demonstrates that a single example of song is enough to discriminate between neighbours and strangers. We discuss which song characteristics are the possible acoustic basis for discrimination in the studied species. [source]


    Not everything is everywhere: the distance decay of similarity in a marine host,parasite system

    JOURNAL OF BIOGEOGRAPHY, Issue 2 2009
    Ana Prez-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]


    Contrasting phylogeographies inferred for the two alpine sister species Cardamine resedifolia and C. alpina (Brassicaceae)

    JOURNAL OF BIOGEOGRAPHY, Issue 1 2009
    Judita Lihov
    Abstract Aim, We use Cardamine alpina and C. resedifolia as models to address the detailed history of disjunctions in the European alpine system. These species grow on siliceous bedrock: C. alpina in the Alps and Pyrenees, and C. resedifolia in several mountain ranges from the Sierra Nevada to the Balkans. We explore differentiation among their disjunct populations as well as within the contiguous Alpine and Pyrenean ranges, and compare the phylogeographical histories of these diploid sister species. We also include samples of the closely related, arctic diploid C. bellidifolia in order to explore its origin and post-glacial establishment. Location, European alpine system, Norway and Iceland. Methods, We employed amplified fragment length polymorphisms (AFLPs). AFLP data were analysed using principal coordinates analysis, neighbour joining and Bayesian clustering, and measures of diversity and differentiation were computed. Results, For the snow-bed species C. alpina (27 populations, 203 plants) we resolved two strongly divergent lineages, corresponding to the Alps and the Pyrenees. Although multiple glacial refugia were invoked in the Pyrenees, we inferred only a single one in the Maritime Alps , from which rapid post-glacial colonization of the entire Alps occurred, accompanied by a strong founder effect. For C. resedifolia (33 populations, 247 plants), which has a broader ecological amplitude and a wider distribution, the genetic structuring was rather weak and did not correspond to the main geographical disjunctions. This species consists of two widespread and largely sympatric main genetic groups (one of them subdivided into four geographically more restricted groups), and frequent secondary contacts exist between them. Main conclusions, The conspicuously different histories of these two sister species are likely to be associated with their different ecologies. The more abundant habitats available for C. resedifolia may have increased the probability of its gradual migration during colder periods and also of successful establishment after long-distance dispersal, whereas C. alpina has been restricted by its dependence on snow-beds. Surprisingly, the arctic C. bellidifolia formed a very divergent lineage with little variation, contradicting a scenario of recent, post-glacial migration from the Alps or Pyrenees. [source]


    Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

    JOURNAL OF BIOGEOGRAPHY, Issue 12 2007
    Patrik Mrz
    Abstract Aim, The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post-glacial history of many high-mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems , the Alps and the Carpathians. Location, Alps and Carpathians. Methods, The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results, Neighbour joining and principal coordinate analyses revealed three well-supported phylogeographical groups of populations corresponding to three disjunct geographical regions , the Alps and the western and south-eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within-population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region-diagnostic markers than those from the south-eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south-western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions, Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south-eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long-term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps. [source]


    Differential genetic influences on competitive effect and response in Arabidopsis thaliana

    JOURNAL OF ECOLOGY, Issue 5 2005
    JAMES F. CAHILL JR
    Summary 1Competition plays an important role in structuring populations and communities, but our understanding of the genetic basis of competitive ability is poor. This is further complicated by the fact that plants can express both competitive effect (target plant influence upon neighbour growth) and competitive response (target plant growth as a function of a neighbour) abilities, with these ecological characteristics potentially being independent. 2Using the model plant species Arabidopsis thaliana, we investigated patterns of intraspecific variation in competitive effect and response abilities and their relationships to other plant traits and resource supply rates. 3Both competitive effect and response were measured for 11 genotypes, including the Columbia ecotype and 10 derived mutant genotypes. Plants were grown alone, with intragenotypic competition, and with intergenotypic competition in a replicated blocked design with high nutrient and low nutrient soil nutrient treatments. We quantified competitive effect and response on absolute and per-gram bases. 4Competitive effect and response varied among genotypes, with the relative competitive abilities of genotypes consistent across fertilization treatments. Overall, high rates of fertilization increased competitive effect and competitive response abilities of all genotypes. Both competitive effect and response were correlated with neighbour biomass, though genotype-specific traits also influenced competitive response. 5At the genotype level, there was no correlation between competitive effect and response in either fertilization treatment. Overall patterns in competitive response appeared consistent among inter- and intragenotypic competition treatments, indicating that a target genotype's response to competition was not driven by the genetic identity of the competitor. 6These findings indicate that within A. thaliana, there is the potential for differential selection on competitive effect and response abilities, and that such selection may influence different sets of plant traits. The concept of a single competitive ability for a given plant is not supported by these data, and we suggest continued recognition of these dual competitive abilities is essential to understanding the potential role of competition in influencing intra- and interspecific processes. [source]


    Competitive effects of grasses and woody plants in mixed-grass prairie

    JOURNAL OF ECOLOGY, Issue 4 2001
    Duane A. Peltzer
    Summary 1,Variation in the competitive ability of plant species may determine their persistence and abundance in communities. We quantified the competitive effects of grasses and woody plants in native mixed-grass prairie on the performance of transplant species and on resources. 2,We separated the effects of grasses, shrubs and intact vegetation containing both grasses and shrubs by manipulating the natural vegetation using selective herbicides to create four neighbourhood treatments: no neighbours (NN), no shrubs (NS), no grasses (NG) and all neighbours (AN). Treatments were applied to 2 2 m experimental plots located in either grass- or shrub-dominated habitats. The effects of grasses and shrubs on resource availability (light, soil moisture, soil available nitrogen) and on the growth of transplants of Bouteloua gracilis, a perennial tussock grass, and Elaeagnus commutata, a common shrub, were measured over two growing seasons. 3,Resource availability was two- to fivefold higher in no neighbour (NN) plots than in vegetated plots (NS, NG, AN) with grasses and shrubs having similar effects. Light penetration declined linearly with increasing grass or shrub biomass, to a minimum of about 30% incident light at 500 g m,2 shoot mass. Soil resources did not decline with increasing neighbour shoot or root mass for either grasses or shrubs, suggesting that the presence of neighbours was more important than their abundance. 4,Transplant growth was significantly suppressed by the presence of neighbours, but not by increasing neighbour shoot or root biomass, except for a linear decline in Bouteloua growth with increasing neighbour shoot mass in plots containing only shrubs. Competition intensity, calculated as the reduction in transplant growth by neighbours, was similar in both grass- and shrub-dominated habitats for transplants of Bouteloua, but was less intense in shrub-dominated habitats for the shrub Elaeagnus. Variation in the persistence and abundance of plants in communities may therefore be more strongly controlled by variation in the competitive effects exerted by neighbours than by differences in competitive response ability. [source]


    An inclusive fitness analysis of altruism on a cyclical network

    JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007
    A. GRAFEN
    Abstract A recent model studies the evolution of cooperation on a network, and concludes with a result connecting the benefits and costs of interactions and the number of neighbours. Here, an inclusive fitness analysis is conducted of the only case solved analytically, of a cycle, and the identical result is obtained. This brings the result within a biologically familiar framework. It is notable that the benefits and costs in the inclusive fitness framework need to be derived, and are not the benefits and costs that are the parameters in the original model. The relatedness is a quadratic function of position in a cycle of size N: an individual is related by 1 to itself, by (N , 5)/(N + 1) to an immediate neighbour, and by very close to ,1/2 to the most distant individuals. The inclusive fitness analysis explains hitherto puzzling features of the results. [source]


    Do competing males cooperate?

    JOURNAL OF FISH BIOLOGY, Issue 2003
    Familiarity, its effect on cooperation during predator inspection in male three-spined sticklebacks (Gasterosteus aculeatus)
    We investigated the trade-off between conflict and cooperation, using predator inspection behaviour in sticklebacks as a model system. Male three-spined sticklebacks (Gasterosteus aculeatus) compete for territories during the breeding season and it has been demonstrated that the level of aggression between territorial neighbours declines with time, a phenomenon known as the dear enemy effect. In this experiment we examine whether this increase in familiarity between territorial neighbours can facilitate an increase in cooperation during predator inspection events. This was analyzed using male sticklebacks from four pond populations, two with and two without predatory rainbow trout (Oncorhyncus mykiss). Males were each exposed to five different treatments: (1) the presentation of a live rainbow trout when alone; (2) with a newly revealed territorial neighbour; (3) with this neighbour after two days of familiarization; (4) with another unfamiliar neighbour (termed a ,floater'); and (5) a second solitary trial (to provide controls at the start and end of the experiment). As predicted, fish from predator-sympatric populations showed higher levels of predator inspection and lower rates of misdirected territorial aggression towards the predator throughout. However, familiarity between neighbouring males did not facilitate an increase in predator inspection behaviour. Instead, predator inspection behaviour decreased throughout treatments involving the presence of any sort of neighbouring male. Familiarity between neighbours did not influence their ability to cooperatively inspect, but only the nature of any aggressive territorial behaviours, all of which detracted equally from individual inspection effort. [source]


    Association of tightly locked occlusion with temporomandibular disorders

    JOURNAL OF ORAL REHABILITATION, Issue 3 2007
    M.-Q. WANG
    summary, The association between teeth loss and temporomandibular disorders (TMD) is still inconclusive. A kind of secondary changes of the occlusion after teeth lose called the tightly locked occlusion (TLO), defined as the occluding contact that delivers angled occlusal force on the drifted neighbour and/or the tipped antagonists of the lost posterior teeth, was hypothesized to be association with TMD. The study aimed at investigating the association between the TLO and TMD. A total of 113 posterior-teeth losing patients, 64 with TMD symptoms (group of TMD) and 49 without (group of TMD-Free) were included. Study casts and joint radiographs were made to diagnose the TLO and joint morphological changes. The simultaneous contribution of the potential variables of gender, age, tooth losing number, the TLO, joint symmetry and signs of osteoarthrosis shown on radiographs were tested through binary logistic regression analysis. In women, the TLO entered into logistic model, and had an effect on the incidence of TMD (P = 0008). The odds ratio of with-TLO versus without-TLO is 26 (95% CI: 12, 58) after controlling for the effect of gender. Age, tooth lose number, joint asymmetry or osseous changes had no effect on the incidence of TMD. The tightly locked occlusion is associated with some signs and symptoms of TMD. Randomized controlled trials will be needed in further studies to test the hypothesis that treatment of a TLO, as defined in the present study, will have a beneficial effect on the signs and symptoms of TMD. [source]


    Orthographic analysis of words during fluency training promotes reading of new similar words

    JOURNAL OF RESEARCH IN READING, Issue 2 2007
    Inez E. Berends
    Remediation of a serious lack in reading fluency often takes the form of repeated reading exercises. The present study examines whether transfer of training effects to untrained (neighbour) words can be enhanced by training with an orthographic focus as compared with emphasising semantics. The effect of oral versus silent reading during training is studied as well. Two groups of reading-disabled children (mean age=7 years, 11 months) were given repeated reading training with limited exposure duration (350 ms) in which 15 target words were repeated 20 times in exercises focused on either orthography (N=26) or semantics (N=25). The children were required to either read the target words aloud or perform the exercises silently, but this requirement appeared to have no effect on the training results. The results show that untrained neighbour words benefited more from training targets with an orthographic focus than from exercises with a semantic emphasis. [source]


    The nature of the Sloan Digital Sky Survey galaxies in various classes based on morphology, colour and spectral features , III.

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010
    Environments
    ABSTRACT We present a study on the environments of the Sloan Digital Sky Survey (SDSS) galaxies divided into fine classes based on their morphology, colour and spectral features. The SDSS galaxies are classified into early-type and late-type; red and blue; passive, H ii, Seyfert and low-ionization nuclear emission-line region (LINER), which returns a total of 16 fine classes of galaxies. We estimate the local number density, target-excluded local luminosity density, local colour, close pair fraction and the luminosity and colour of the brightest neighbour, which are compared between the fine classes comprehensively. The morphology,colour class of galaxies strongly depends on the local density, with the approximate order of high-density preference: red early-type galaxies (REGs); red late-type galaxies (RLGs); blue early-type galaxies (BEGs) and blue late-type galaxies (BLGs). We find that high-density environments (like cluster environments) seem to suppress active galactic nucleus activity. The pair fraction of H ii REGs does not show a statistically significant difference from that of passive REGs, while the pair fraction of H ii BLGs is smaller than that of non-H ii BLGs. H ii BLGs show obvious double (red + blue) peaks in the distribution of the brightest neighbour colour, while red galaxies show a single red peak. The brightest neighbours of Seyfert BLGs tend to be blue, while those of LINER BLGs tend to be red, which implies that the difference between Seyfert and LINER may be related to the pair interaction. Other various environments of the fine classes are investigated, and their implications for galaxy evolution are discussed. [source]


    The clustering of narrow-line AGN in the local Universe

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006
    Cheng Li
    ABSTRACT We have analysed the clustering of ,90 000 narrow-line active galactic nuclei (AGN) drawn from the Data Release 4 (DR4) of the Sloan Digital Sky Survey. Our analysis addresses the following questions. (i) How do the locations of galaxies within the large-scale distribution of dark matter influence ongoing accretion on to their central black holes? (ii) Is AGN activity triggered by interactions or mergers between galaxies? We compute the cross-correlation between AGN and a reference sample of galaxies drawn from the DR4. We compare this to results for control samples of inactive galaxies matched simultaneously in redshift, stellar mass, concentration, velocity dispersion and mean stellar age, as measured by the 4000- break strength. We also compare near-neighbour counts around AGN and around the control galaxies. On scales larger than a few Mpc, AGN have almost the same clustering amplitude as the control sample. This demonstrates that AGN host galaxies and inactive control galaxies populate dark matter haloes of similar mass. On scales between 100 kpc and 1 Mpc, AGN are clustered more weakly than the control galaxies. We use mock catalogues constructed from high-resolution N -body simulations to interpret this antibias, showing that the observed effect is easily understood if AGN are preferentially located at the centres of their dark matter haloes. On scales less than 70 kpc, AGN cluster marginally more strongly than the control sample, but the effect is weak. When compared to the control sample, we find that only one in 100 AGN has an extra neighbour within a radius of 70 kpc. This excess increases as a function of the accretion rate on to the black hole, but it does not rise above the few per cent level. Although interactions between galaxies may be responsible for triggering nuclear activity in a minority of nearby AGN, some other mechanism is required to explain the activity seen in the majority of the objects in our sample. [source]


    International rivers and national security: The Euphrates, Ganges,Brahmaputra, Indus, Tigris, and Yarmouk rivers1

    NATURAL RESOURCES FORUM, Issue 4 2008
    Neda A. Zawahri
    Abstract To understand a state's incentives to invest in conflict or cooperation over their international rivers, this paper argues that it is necessary to appreciate the relationships a river can create and the national security threat riparians may confront. Rivers impose interdependent and vulnerable relationships, which can compromise a state's ability to respond effectively to floods and droughts, meet its domestic food and energy needs, dredge the river, maintain its drainage systems, and allocate its domestic water budget. The inability to accomplish these tasks can contribute to social, economic, and political losses that may threaten a state's territorial integrity. Regardless of whether a state is upstream or downstream, from these relationships it acquires leverage to manipulate the interdependence and vulnerability to inflict losses on its riparian neighbour. This argument challenges several assumptions within the existing literature, including the belief that a shortage of freshwater is the initial force producing a national security threat and that an upstream,downstream river bequeaths all advantages on the upstream state and leaves the downstream state purely dependent. As the paper shows, riparians confront a more complex relationship than captured by the existing literature. [source]


    What's at Stake in Natural Law?

    NEW BLACKFRIARS, Issue 1023 2008
    Barrister, David McIlroy M.A. (Cantab.), Mtr Dt (Toulouse)
    Abstract Something like natural law is required if Christians are to say that Jesus Christ is as relevant to human beings of every age and in every place that we have ever existed as a race. There must be something stable about the human condition which means that we are all alike in need of a Saviour. That something is the fact that we are created to love God and to love our neighbour. This much is revealed to all humankind. For the Apostle Paul and Thomas Aquinas the natural law was not given as an alternative method of salvation but rather to explain the justice of God's judgment and the utter gratuity of divine grace. Similarly, natural theology is not an assertion that faith in Christ is optional but rather that all human beings are culpable if they do not recognise that there is a god who created them and rewards those who seek God. Natural theology is the minimum content of faith where Christ has not been proclaimed; it is no substitute for explicit faith in Christ when He has been revealed. [source]


    Competitive ability not kinship affects growth of Arabidopsis thaliana accessions

    NEW PHYTOLOGIST, Issue 1 2010
    Frdric Masclaux
    Summary ,In many organisms, individuals behave more altruistically towards relatives than towards unrelated individuals. Here, we conducted a study to determine if the performance of Arabidopsis thaliana is influenced by whether individuals are in competition with kin or non-kin. ,We selected seven pairs of genetically distinct accessions that originated from local populations throughout Europe. We measured the biomass of one focal plant surrounded by six kin or non-kin neighbours in in vitro growth experiments and counted the number of siliques produced per pot by one focal plant surrounded by four kin or non-kin neighbours. ,The biomass and number of siliques of a focal plant were not affected by the relatedness of the neighbour. Depending on the accession, a plant performed better or worse in a pure stand than when surrounded by non-kin plants. In addition, whole-genome microarray analyses revealed that there were no genes differentially expressed between kin and non-kin conditions. ,In conclusion, our study does not provide any evidence for a differential response to kin vs non-kin in A. thaliana. Rather, the outcome of the interaction between kin and non-kin seems to depend on the strength of the competitive abilities of the accessions. [source]


    Cuticular hydrocarbons in a termite: phenotypes and a neighbour,stranger effect

    PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2002
    Manfred Kaib
    Abstract The composition of cuticular hydrocarbons of different colonies of the fungus-growing termite Macrotermes falciger shows considerable intercolonial variation. Ordination, as well as cluster analyses, separate profiles into three distinct chemical phenotypes. Behavioural tests with major workers reveal no alarm behaviour or mortality in pairings of workers from the same colony but a full range from no alarm to overt aggression, with associated death, when individuals were paired from different colonies. The level of mortality increases with differences in the composition of cuticular hydrocarbons between colonies. However, no mortality occurs in pairings of individuals from neighbouring colonies belonging to different phenotypes. The data thus provide evidence for a ,neighbour,stranger' effect (so-called ,dear-enemy' phenomenon) in termites. [source]


    Desire, demand and psychotherapy: on large groups and Neighbours

    PSYCHOTHERAPY AND POLITICS INTERNATIONAL, Issue 3 2008
    Stephen FroshArticle first published online: 24 SEP 200
    Abstract Explanations of the disturbing effects of large groups are sought in the group analytic literature, where there is an emphasis on boundary disturbance, and in contemporary psychoanalytic and social theory, where the peculiar nature of the ,neighbour' has become a topic for investigation. It is argued that the human subject is an ,interrupted' subject, with the other/neighbour being a key figure in creating this interruption. In large groups, the alien nature of the neighbour who is both close and unknowable comes to the fore, disrupting attempts to cover over this ,interruption' and promoting confusion and dislocation. The large group is consequently expressive of specific forms of contemporary sociality, and also suggestive for an ethical practice of psychotherapy that does not reduce to consolation. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Genetic diversity in a collection of old and new bread wheat cultivars from Iran as revealed by simple sequence repeat-based analysis

    ANNALS OF APPLIED BIOLOGY, Issue 1 2009
    S.A. Mohammadi
    Abstract Genetic diversity in a collection of 70 bread wheat (Triticum aestivum) genotypes was studied using 73 microsatellite [simple sequence repeat (SSR)] loci evenly spaced on wheat chromosomes. A total of 592 alleles with an average of 8.53 allele/locus were detected, of which 185 (31.25%) occurred only in a specific group of genotypes. A set of SSR markers consisted of 22 loci with polymorphic information content values of 0.80 or higher were selected for rapid fingerprinting of many genotypes. Average of gene diversity was 0.74 0.017, and significant difference between observed and maximum theoretical values of gene diversity in the analysed SSR loci was obtained using a paired t -test. Genetic distance-based clustering methods including unweighted pair group method with arithmetic average and neighbour joining (NJ) were used for grouping of genotypes. The resulted dendrogram based on NJ and number of differences coefficient hinted of the existence of three groups. This grouping was in agreement with the pedigree information and confirmed by high within-group bootstrap value. A comparatively higher genetic diversity in the studied wheat collection as revealed by presence of high allelic diversity and large number of specific alleles could be utilised in development of new cultivars with desired characteristics. [source]


    Hopkins Architects' Kroon Hall, Yale University

    ARCHITECTURAL DESIGN, Issue 6 2009
    Jayne Merkel
    Abstract Stone-walled, barrel-vaulted Kroon Hall, the hulking new home of Yale University's pioneering School of Forestry and Environmental Studies, is a living laboratory of energy-efficient design as well as a sympathetic neighbour. Jayne Merkel describes the numerous problems the architects had to solve to make it compatible with the historic campus and actively experimental at the same time. Its pioneering green agenda even determined the character of its interior space warmly and subtly. Copyright 2009 John Wiley & Sons, Ltd. [source]