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Spatial Distribution Patterns (spatial + distribution_pattern)
Selected AbstractsANALYSIS ON THE DYNAMICS OF SPATIAL DISTRIBUTION PATTERN OF MIXED SPIDER POPULATION IN RICE FIELDINSECT SCIENCE, Issue 4 2004Zhi Wang Abstract The results make it clear that there are total 11 families, 29 genera and 43 species of spiders in the rice field of Dong Fang Hong Farm. Among them, there are 8 families, 19 genera and 28 species in the early rice field, and 10 families, 27 genera and 36 species in the late rice field. The spatial distribution pattern of mixed spider populations in rice fields was different during different development stages of rice plant. During the prophase, metaphase and anaphase of early rice plant development, the spatial distribution pattern of mixed spider populations was aggregative, random and aggregative respectively. During the prophase, metaphase and anaphase of late rice plant development, the spatial distribution pattern was uniform, aggregative and uniform respectively. [source] Spatial Distribution Patterns of Jumping Spiders Associated with Terrestrial BromeliadsBIOTROPICA, Issue 4 2004Gustavo Q. Romero ABSTRACT The jumping spiders Eustiromastix native, Psecas sumptuosus, and Uspachus sp. n. (Salticidae) live on terrestrial bro-meliads in areas with different phytophysiognomies in southeastern and northeastern Brazil. To understand these spider,plant interactions, we investigated if (1) these spiders were associated specifically with bromeliads, (2) the spiders utilized particular bromeliad species, and (3) plant size and density of bromeliads affected spider distribution. The jumping spiders were not found outside bromeliads, indicating a strict spider,plant association. Eustiromastix and Uspachus occupied bromeliads in open areas, whereas Psecas was found on forest bromeliads. Eustiromastix occurred at a higher frequency on larger bromeliads and in patches with higher bromeliad density. This is one of the few studies to demonstrate specific relationships between jumping spiders and a particular plant type. RESUMO As aranhas saltadoras Eustiromastix native, Psecas sumptuosus e Uspachus sp. n. (Salticidae) vivem sobre bromélias terrestres em áreas com diferentes fitofisionomias no sudeste e nordeste do Brasil. Para compreender estas interaçóes aranha-planta, nós investigamos se (1) estas aranhas estavam associadas especificamente a bromélias, (2) as aranhas utilizam espécies particulares de bromélias e (3) tamanho e densidade das bromélias afetam a distribuiçáo das aranhas. As aranhas saltadoras não foram encontradas fora das bromélias, indicando uma associaçáo estrita entre aranha e planta. Eustiromastix e Uspachus ocuparam bromelias em areas abertas enquanto Psecas foi encontrada em bromélias de floresta. Eustiromastix ocorreu em maior freqüéncia sobre bromélias maiores e em manchas com maior densidade de bromélias. Este estudo é um dos poucos a demonstrar relaço,es especificas entre aranhas saltadoras e um tipo particular de planta. [source] Habitat selection and diel distribution of the crustacean zooplankton from a shallow Mediterranean lake during the turbid and clear water phasesFRESHWATER BIOLOGY, Issue 3 2007BRUNO B. CASTRO Summary 1. The fish fauna of many shallow Mediterranean Lakes is dominated by small-bodied exotic omnivores, with potential implications for fish,zooplankton interactions still largely unknown. Here we studied diel variation in the vertical and horizontal distribution of the crustacean plankton in Lake Vela, a shallow polymictic and eutrophic lake. Diel sampling was carried out on three consecutive days along a horizontal transect, including an open-water station and a macrophyte (Nymphaea alba) bed. Since transparency is a key determinant of the predation risk posed by fish, the zooplankton sampling campaigns were conducted in both the turbid (autumn) and clear water (spring) phases. 2. In the turbid phase, most taxa were homogeneously distributed along the vertical and horizontal axes in the three consecutive days. The only exception was for copepod nauplii, which showed vertical heterogeneity, possibly as a response to invertebrate predators. 3. In the clear water phase, most zooplankton taxa displayed habitat selection. Vertically, the general response consisted of a daily vertical migration (DVM), despite the limited depth (1.6 m). Horizontally, zooplankters showed an overall preference for the pelagic zone, independent of the time of the day. Such evidence is contrary to the postulated role of macrophytes as an anti-predator refuge for the zooplankton. 4. These vertical (DVM) and horizontal (macrophyte-avoidance) patterns were particularly conspicuous for large Daphnia, suggesting that predation risk from size-selective predators (fish) was the main factor behind the spatial heterogeneity of zooplankton in the spring. Thus, the difference in the zooplankton spatial distribution pattern and habitat selection among seasons (turbid and clear water phases) seems to be mediated the predation risk from fish, which is directly related to water transparency. 5. The zooplankton in Lake Vela have anti-predator behaviour that minimises predation from fish. We hypothesise that, due to the distinct fish community of shallow Mediterranean lakes, aquatic macrophytes may not provide adequate refuge to zooplankters, as seen in northern temperate lakes. [source] ANALYSIS ON THE DYNAMICS OF SPATIAL DISTRIBUTION PATTERN OF MIXED SPIDER POPULATION IN RICE FIELDINSECT SCIENCE, Issue 4 2004Zhi Wang Abstract The results make it clear that there are total 11 families, 29 genera and 43 species of spiders in the rice field of Dong Fang Hong Farm. Among them, there are 8 families, 19 genera and 28 species in the early rice field, and 10 families, 27 genera and 36 species in the late rice field. The spatial distribution pattern of mixed spider populations in rice fields was different during different development stages of rice plant. During the prophase, metaphase and anaphase of early rice plant development, the spatial distribution pattern of mixed spider populations was aggregative, random and aggregative respectively. During the prophase, metaphase and anaphase of late rice plant development, the spatial distribution pattern was uniform, aggregative and uniform respectively. [source] Spatial structure and genetic diversity of two tropical tree species with contrasting breeding systems and different ploidy levelsMOLECULAR ECOLOGY, Issue 3 2004Kevin K. S. Ng Abstract Analyses of the spatial distribution pattern, spatial genetic structure and of genetic diversity were carried out in two tropical tree species with contrasting breeding systems and different ploidy levels using a 50-ha demographic plot in a lowland dipterocarp forest in Peninsular Malaysia. Shorea leprosula is a diploid and predominantly outcrossed species, whereas S. ovalis ssp. sericea is an autotetraploid species with apomictic mode of reproduction. Genetic diversity parameters estimated for S. leprosula using microsatellite were consistently higher than using allozyme. In comparisons with S. leprosula and other tropical tree species, S. ovalis ssp. sericea also displayed relatively high levels of genetic diversity. This might be explained by the lower pressure of genetic drift due to tetrasomic inheritance, and for autotetraploids each locus can accommodate up to four different alleles and this allows maintenance of more alleles at individual loci. The observed high levels of genetic diversity in S. ovalis ssp. sericea can also be due to a random retention of more heterogeneous individuals in the past, and the apomictic mode of reproduction might be an evolutionary strategy, which allows the species to maintain high levels of genetic diversity. The spatial distribution pattern analyses of both species showed significant levels of aggregation at small and medium but random distribution at the big diameter-class. The decrease in magnitude of spatial aggregation from small- to large-diameter classes might be due to compensatory mortality during recruitment and survival under competitive thinning process. Spatial genetic structure analyses for both species revealed significant spatial genetic structure for short distances in all the three diameter-classes. The magnitude of spatial genetic structure in both species was observed to be decreasing from smaller- to larger-diameter classes. The high spatial genetic structuring observed in S. ovalis ssp. sericea at the small-diameter class is due primarily to limited seed dispersal and apomictic mode of reproduction. The similar observation in S. leprosula, however, can be explained by limited seed and pollen dispersal, which supports further the fact that the species is pollinated by weak fliers, mainly of Thrips and Megalurothrips in the lowland dipterocarp forest. [source] Human impacts on the species,area relationship in reef fish assemblagesECOLOGY LETTERS, Issue 9 2007Derek P. Tittensor Abstract The relationship between species richness and area is one of the oldest, most recognized patterns in ecology. Here we provide empirical evidence for strong impacts of fisheries exploitation on the slope of the species,area relationship (SAR). Using comparative field surveys of fish on protected and exploited reefs in three oceans and the Mediterranean Sea, we show that exploitation consistently depresses the slope of the SAR for both power-law and exponential models. The magnitude of change appears to be proportional to fishing intensity. Results are independent of taxonomic resolution and robust across coral and rocky reefs, sampling protocols and statistical methods. Changes in species richness, relative abundance and patch occupancy all appear to contribute to this pattern. We conclude that exploitation pressure impacts the fundamental scaling of biodiversity as well as the species richness and spatial distribution patterns of reef fish. We propose that species,area curves can be sensitive indicators of community-level changes in biodiversity, and may be useful in quantifying the human imprint on reef biodiversity, and potentially elsewhere. [source] The effects of dispersal mode on the spatial distribution patterns of intertidal molluscsJOURNAL OF ANIMAL ECOLOGY, Issue 4 2001M. P. Johnson Summary 1As many species of marine benthic invertebrates have a limited capacity for movement as adults, dispersal mode is often considered as a determinant of geographical ranges, genetic structure and evolutionary history. Species that reproduce without a larval stage can only disperse by floating or rafting. It is proposed that the colonization processes associated with such direct developing species result in spatial distributions that show relatively greater fine scale patchiness than the distributions of species with a larval dispersal stage. This hypothesis was tested by collecting molluscs at different spatial scales in the Isle of Man. 2Spatial distribution patterns supported the predictions based on dispersal mode. Estimated variance components for species with larval dispersal suggested that the majority of the spatial variation was associated with variation between shores. In comparison, there was relatively more variability within shores for abundance counts of species with direct development. 3Multivariate analyses reflected the univariate results. An assemblage of direct developers provided a better discrimination between sites (100 m separation) but the group of species with larval dispersal gave a clearer separation of shores (separated by several km). 4The fine scale spatial structure of direct developing species was reflected in higher average species diversity within quadrats. Species richness also reflected dispersal mode, with a higher fraction of the regional species pool present for direct developers in comparison to species with larval dispersal. This may reflect the improved local persistence of taxa that avoid the larval dispersal stage. [source] Spatial distribution of ants (Hymenoptera: Formicidae), vine mealybugs and mealybug parasitoids in vineyardsJOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2010N. Mgocheki Abstract The mutualistic association between some ant species and honeydew-producing Hemiptera has been shown to influence the distribution patterns and abundance of these hemipterans and their natural enemies. We studied the spatial distribution patterns of three ant species, mealybugs and mealybug parasitoids for two consecutive growing seasons on three wine grape farms in the Western Cape, South Africa. During the study period, no ant or mealybug controls were applied. Ant and mealybug monitoring was conducted on a total of 21 ha using a presence/absence sampling system, while parasitoids were collected from infested mealybug females. Spatial analysis by distance indices was used to analyse spatial distribution of insects and ArcViewÔ was used to map the gap, patch and local association indices where significant association and disassociation occurred. Significant associations were found between some ants and parasitoids, while significant disassociations between the ants Crematogaster peringueyi and Linepithema humile; and also between Crematogaster peringueyi and Anoplolepis steingroeveri were found. Interspecific competition between ant species could play a role in the distribution of parasitoids and mealybugs. Our results stress the importance of monitoring for ants and mealybugs and further highlight the importance of restricted chemical applications against ants during the growing season. [source] Spatial variations in the composition and abundance of zooplankton in the Bahir Dar Gulf of Lake Tana, EthiopiaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Tunde Ohiokhioya Thadeus Imoobe Abstract The zooplankton in the littoral and open water zones of Bahir Dar Gulf, Lake Tana, collected in June and July 2007, were investigated using basic statistical measurement of diversity indices and one way analysis of variance to characterize the zooplankton fauna, with respect to its composition, abundance and spatial distribution patterns. The zooplankton composition was typical of a tropical freshwater lake, with a total of 44 species made up of sixteen rotifers, sixteen c1adocerans and twelve copepods and their developing stages in the following order of dominance; Rotifera > Cladocera > Cylopoida > Calanoida. Variation in spatial distribution was noticeable, the abundance of zooplankton was significantly higher (P < 0.05) at the littoral zone (Stations 2 and 3) than the open water (Station 1) as a result of the preponderance of the small-bodied nauplii stages, small rotifers and c1adocerans particularly Bosmina longirostris. Species richness, evenness, and diversity also increased as abundance increased in the littoral zones of the lake. The rotifers, particularly the brachionids Keratella and Brachionus spp., which are considered good indicators of lake trophic status constituted the dominant zooplankton group in terms of abundance and diversity, thus indicating that the lake has a high fisheries potential. Résumé Le zooplancton des berges et des eaux ouvertes du golfe de Bahir Dar, récolté en juin et juillet 2007 dans le lac Tana, a étéétudié en utilisant des indices de mesures statistiques de base et une analyse de la variance à une voie, pour caractériser la faune du zooplancton, tant au point de vue de la composition que de l'abondance et du schéma de distribution spatiale. La composition du zooplancton était typique d'un lac d'eau douce tropical, avec un total de 44 espèces réparties entre 16 rotifères, 16 cladocères et 12 copépodes à différents stades de développement dans l'ordre de prépondérance qui suit : Rotifères > Cladocères > Cylopoïdes > Calanoïdes. Il y avait une variation notable de la distribution spatiale : l'abondance de zooplancton était significativement plus grande (P < 0.05) dans la zone littorale (Stations 2 et 3) qu'en haute eau (Station 1), suite à la prépondérance des petits corpuscules comme les stades nauplius, les petits rotifères et cladocères, et particulièrement Bosmina longirostris. La richesse en espèces, l'uniformité et la diversité augmentaient aussi en même temps que l'abondance dans les zones littorales du lac. Les rotifères, et particulièrement Keratella et Brachionus spp., qui sont considérés comme de bons indicateurs du statut trophique du lac étaient le groupe de zooplancton dominant en termes d'abondance et de diversité, ce qui indique que le lac a un fort potentiel piscicole. [source] Genetic population structure, queen supersedure and social polymorphism in a social HymenopteraJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2007K. BARGUM Abstract In social insects, the emergence of multiple queening is linked to changes in a suite of traits such as the reproductive life span of queens, mating patterns and population structure. We investigated queen turnover, colony longevity, spatial distribution patterns and genetic differentiation in a population of the socially polymorphic ant Formica fusca. Genetic differentiation between the social forms was absent, and mating patterns were similar in the two forms. The spatial distribution of single- and multi-queen colonies indicated an absence of colony reproduction by budding in both colony types. However, the rate of queen supersedure was high in multi-queen colonies and absent in single-queen ones. The social structure of colonies remained stable across years, but colony mortality did not differ between the two social forms. These results imply that differences between social types may appear and persist also in sympatry, and that these differences may occur in some traits, but not others, despite the presence of homogenizing gene flow. [source] Johansson revisited: the spatial structure of epiphyte assemblagesJOURNAL OF VEGETATION SCIENCE, Issue 1 2007Gerhard Zotz Abstract Question: Vertical zonation schemes are widely used in biodiversity studies with vascular epiphytes as a tool to capture spatial distribution patterns, the one most commonly used was proposed by Johansson more than 30 years ago. Does a survey of the epiphytes found on larger trees really yield a representative sample of the local community? Location: Lowland rainforest of the San Lorenzo Crane Plot, Republic of Panama. Methods: A complete census of the vascular epiphytes on all trees > 1 cm DBH in 0.4 ha of undisturbed lowland forest was analysed with both cluster and discriminant analysis to detect groupings of epiphyte species. Results: Six different groups of species were detected, five of them preferring different substrates on larger trees (as defined by (1) the height above ground at the attachment site, (2) the diameter of the substrate and (3) the occurrence on stem vs branches/twigs) and resembling to some extent the original Johansson zones. A sixth group of epiphytes, comprising ca. 10% of all taxa, was almost always found on small diameter stems and branches of trees with small DBH at lower and intermediate heights within the forest. Conclusions: Applying pre-established zonation schemes may lead to misleading results in biodiversity studies with epiphytes. Important aspects of spatial distribution patterns may be missed, and the determination of relative species abundances may carry a strong quantitative and qualitative bias when analyses rely completely on epiphytic plants found on larger trees. [source] Spatial patterns and associations in a Quercus-Betula forest in northern ChinaJOURNAL OF VEGETATION SCIENCE, Issue 3 2004J.H. Hou Abstract: Question: Are species-specific regeneration strategies and competition the dominant processes facilitating species coexistence in a Quercus liaotungensis dominated temperate deciduous forest? Location: Dongling Mountains, North China, 1300 m a.s.l. Methods: Ripley's K -function was used to characterize the spatial patterns and spatial associations of two dominant tree species, Quercus liaotungensis and Betula dahurica, and a common subcanopy species, Acer mono, at different growth stages (adult, sapling, seedling). Results: Seedlings, saplings and adults of all three species exhibited clumped distributions at most spatial scales. Quercus seedlings and saplings were positively associated with conspecific adult trees and spatially independent of dead trees suggesting that seed dispersal and vegetative regeneration influenced the spatial patterning of Quercus trees. Betula seedlings and saplings were positively associated with both live and dead trees of conspecific adults at small scales (<5 m) but negatively associated with live and dead trees of other species indicating sprouting as an important mechanism of reproduction. Saplings of Acer had a strong spatial dependence on the distribution of conspecific adult trees indicating its limited seed dispersal range. Negative associations between adult trees of Betula and Quercus demonstrated interspecific competition at local scales (<5 m). Conclusions: Different regeneration strategies among the three species play an important role in regulating their spatial distribution patterns, while competition between individuals of Betula and Quercus at the adult stage also contributes to spatial patterning of these communities. The recruitment limitations of Betula and Quercus may affect the persistence of these species and the long-term dynamics of the forest. [source] Actual status of the sea urchin Diadema aff. antillarum populations and macroalgal cover in marine protected areas compared to a highly fished area (Canary Islands,eastern Atlantic Ocean)AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2008José Carlos Hernández Abstract 1.The aim was to determine the status of subtidal rocky benthic assemblages in three marine protected areas (MPAs) of the Canary Islands: (1) La Graciosa; (2) Mar de Las Calmas; (3) La Palma. Sea urchin (Diadema aff. antillarum) populations and non-crustose macroalgal cover were surveyed, and used as an indicator of conservation status in the three MPAs as well as in a highly fished area (HFA-Tenerife Island). 2.Comparing characteristics between each MPA and the HFA, and considering issues of management and design, it was concluded that the three MPAs each have a different conservation status. ,Mar de Las Calmas' marine reserve was found to have the most desirable conservation status, followed by ,La Palma' marine reserve based on sea urchin populations and non-crustose macroalgae assemblages. 3.Conversely, ,La Graciosa' had the highest density of D. aff. antillarum and the lowest cover of non-crustose macroalgae out of the three MPAs. Values were comparable to those at the HFA, which shows ,La Graciosa' to have the undesired conservation status. 4.Different spatial distribution patterns of non-crustose macroalgal as well as different algal composition cover were observed between the three MPAs and the HFA. These differences were principally attributed to the intensity of grazing activity of the key herbivore D. aff. antillarum. It is suggested that the different study areas correspond to different phase shifts that imply differing resilience of systems that should be taken into a count in future conservation strategies. Copyright © 2007 John Wiley & Sons, Ltd. [source] ASSESSING WHAT LIES BENEATH THE SPATIAL DISTRIBUTION OF A ZOOARCHAEOLOGICAL RECORD: THE USE OF GIS AND SPATIAL CORRELATIONS AT EL MIRÓN CAVE (SPAIN)*ARCHAEOMETRY, Issue 3 2009A. B. MARÍN ARROYO Geographical Information Systems (GIS) are being incorporated into archaeology as a technique to improve the understanding of spatial organization and the relationships among finds within specific areas. Although their use as a basic tool in predicting the location of archaeological sites or in assessing the extent of their catchment areas is relatively common, in general, they have less often been applied to the study of the spatial distribution of archaeological remains within individual deposits, and in particular to faunal assemblages. Despite this, they can prove essential to understanding dispersion and grouping patterns within deposits fully, and, together with various correlation analytical techniques, they provide valuable information about the economic organization of settlements and inhabitant lifeways. To demonstrate the potential of this methodology, a zooarchaeological GIS has been prepared for the Middle and Late Magdalenian and Azilian layers in El Mirón Cave (eastern Cantabria, Spain), and the spatial distribution patterns of various attributes of the archaeological record have been analysed. Significant conclusions in terms of type and duration of human occupation have been drawn. [source] Local and regional spatial distribution of an eruptive and a latent herbivore insect speciesAUSTRAL ECOLOGY, Issue 2 2003Katia T. Ribeiro Abstract In this work, we investigated the spatial distribution of two sessile insect herbivores over the entire range of their host plant, Coccoloba cereifera, a sclerophyllous shrub endemic to Serra do Cipó, Brazil. The two insects have very distinct life histories and dispersal behaviours and we hypothesized that their classification into behavioural syndromes could be used to predict their spatial distribution patterns. Abgrallaspis cyanophylli (Homoptera) is an armoured scale insect that fits well into the eruptive syndrome. Stenapion aff. contrarium (Coleoptera) is a petiole borer with wide search capabilities, which fits into the latent syndrome. We expected that Abgrallaspis would follow the host plant aggregation pattern whereas Stenapion would be distributed more uniformly through the region and be less affected by host aggregation. We counted the number of attacked and non-attacked ramets within two perpendicular belt transects as well as within a 20 m × 20 m quadrat placed over a dense shrub aggregation. Local quadrat covariance methods were used to estimate the spatial pattern of each insect. At fine scales, we found Stenapion evenly distributed over the host plant and Abgrallaspis with a significantly aggregated pattern. This finding is in accordance with our hypothesis. At larger scales, however, this pattern was lost and the results were largely variable. We conclude that the classification of insects into behavioural syndromes may be useful to predict distribution patterns at fine scales. At larger scales, however, history and chance events may be more important. [source] | |||||||||||||||||||||||||