bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Phosphorus, Light Climate, and Photosynthesis between Two Culturally Eutrophied Bays: Green Bay, Lake Michigan, and the Bay of Quinte, Lake Ontario
Authors: Millard E. S. , Sager P. E.
Published: July 2008

Trophic status, response to phosphorus control, and the underwater light climate were compared for the major bays of Lake Michigan (Green Bay) and Lake Ontario (Bay of Quinte). The Bay of Quinte has shown the greatest response to phosphorus controls, but conditions were not as eutrophic prior to controls as in Green Bay. There were distinct spatial gradients in trophic indicators (chlorophyll a and light extinction) as well as in background light extinction in both bays. Photosynthetic rates remain higher in Green Bay than in the Bay of Quinte, although this is more pronounced for daily photosynthesis per cubic metre at optimal light than for daily rates per square metre. Background light extinction reduced areal photosynthesis in Green Bay because of competition for light absorption between chlorophyll and suspended solids. Potential effects of remedial actions such as reduced phosphorus and suspended loading on phytoplankton photosynthesis were assessed. Lowering chlorophyll would cause a significant decline in areal photosynthesis rates but decreasing background light extinction could lead to higher rates.
Size-Based Structure and Production in the Pelagia of Lakes Ontario and Michigan
Authors: Sprules W. Gary , Goyke Andy P.
Published: July 2008

Analytical solutions to allometric models of predator–prey interactions in aquatic ecosystems indicate that normalized biomass spectra should consist of a smooth quadratic trend around which periodic oscillations occur. We confirm these assertions by showing that parabolas provide good models of normalized biomass as a function of body mass within homogeneous trophic groupings of organisms (phytoplankton, zooplankton, or fish) in the pelagic food webs of Lakes Ontario and Michigan. In addition, we show that the normalized biomass spectrum for the whole pelagic community in these lakes can be modelled by a series of parabolas of constant curvature that are aligned along a smooth quadratic base, as predicted by theory. Total secondary production in Lake Ontario is predicted from these models to be 234 kcal∙m−2∙yr−1 (1 kcal = 4.19 kJ), which compares favourably with sampling estimates of about 154 kcal∙m−2∙yr−1 for the whole community except rotifers and some hypolimnetic organisms, but both are higher than particle-size conversion efficiency estimates of 75–125 kcal∙m−2∙yr−1.
Use of transferableNicotiana tabacumL. microsatellite markers for investigating genetic diversity in the genusNicotiana
Authors: Moon H. S. , Nicholson J. S. , Lewis R. S.
Published: July 2008

The recent development of microsatellite markers for tobacco, Nicotiana tabacum L., may be valuable for genetic studies within the genus Nicotiana . The first objective was to evaluate transferability of 100 N. tabacum microsatellite primer combinations to 5 diploid species closely related to tobacco. The number of primer combinations that amplified scorable bands in these species ranged from 42 to 56. Additional objectives were to assess levels of genetic diversity amongst available accessions of diploid relatives closely related to tobacco (species of sections Sylvestres and Tomentosae), and to evaluate the efficacy of microsatellite markers for establishing species relationships in comparison with existing phylogenetic reconstructions. A subset of 46 primer combinations was therefore used to genotype 3 synthetic tobaccos and an expanded collection of 51 Nicotiana accessions representing 15 species. The average genetic similarity for 7 diverse accessions of tobacco was greater than the average similarity for N. otophora accessions, but lower than the average genetic similarities for N. sylvestris , N. tomentosa , N. kawakamii , and N. tomentosiformis accessions. A microsatellite-based phylogenetic tree was largely congruent with taxonomic representations based on morphological, cytological, and molecular observations. Results will be useful for selection of parents for creation of diploid mapping populations and for germplasm introgression activities.
Nuclear DNA amount and genome downsizing in natural and synthetic allopolyploids of the generaAegilopsandTriticum
Authors: Eilam T. , Anikster Y. , Millet E. , Manisterski J. , Feldman M.
Published: July 2008

Recent molecular studies in the genera Aegilops and Triticum showed that allopolyploidization (interspecific or intergeneric hybridization followed by chromosome doubling) generated rapid elimination of low-copy or high-copy, non-coding and coding DNA sequences. The aims of this work were to determine the amount of nuclear DNA in allopolyploid species of the group and to see to what extent elimination of DNA sequences affected genome size. Nuclear DNA amount was determined by the flow cytometry method in 27 natural allopolyploid species (most of which were represented by several lines and each line by several plants) as well as 14 newly synthesized allopolyploids (each represented by several plants) and their parental plants. Very small intraspecific variation in DNA amount was found between lines of allopolyploid species collected from different habitats or between wild and domesticated forms of allopolyploid wheat. In contrast to the constancy in nuclear DNA amount at the intraspecific level, there are significant differences in genome size between the various allopolyploid species, at both the tetraploid and hexaploid levels. In most allopolyploids nuclear DNA amount was significantly less than the sum of DNA amounts of the parental species. Newly synthesized allopolyploids exhibited a similar decrease in nuclear DNA amount in the first generation, indicating that genome downsizing occurs during and (or) immediately after the formation of the allopolyploids and that there are no further changes in genome size during the life of the allopolyploids. Phylogenetic considerations of the origin of the B genome of allopolyploid wheat, based on nuclear DNA amount, are discussed.
Comparative FISH mapping of two highly repetitive DNA sequences in Hordeum chilense (Roem. et Schult.)
Authors: Marín S. , Martín A. , Barro F.
Published: July 2008

Hordeum chilense Roem. et Schult. (2n = 14) is an autogamous wild barley from Chile and Argentina included in the section Anisolepis Nevski. This species shows interesting agronomic traits that can be incorporated into crop plant species. Hordeum chilense has been successfully crossed with species of the genus Aegilops. Among the amphiploids obtained, the hexaploid tritordeum (2n = 6x = 42, AABBHchHch) is outstanding and shows good agronomic characteristics, suggesting its potential either as a new crop or as a bridge species to introgress interesting traits into cultivated cereals. The aim of the present work was to study the hybridization patterns of the two repetitive DNA probes pAs1 and pSc119.2 to evaluate their utility for the identification of H. chilense chromosomes. Fourteen lines of H. chilense were analyzed with fluorescent in situ hybridization using probes pSc119.2 and pAs1. The probe pAs1 was more widely dispersed than pSc119.2 over the H. chilense (Hch) genome. We found 89 different signals for pAs1, distributed evenly over the whole genome, and 10 for pSc119.2, located mainly over the telomeric regions. Five distinct hybridization signals were found for pAs1 and four distinct signals for pSc119.2. These signals allow the identification of different H. chilense lines. For example, centromeric signals for pAs1 on the short arms of chromosomes 1 and 7 identify line H46, and a telomeric signal for pSc119.2 on the short arm of chromosome 2 identifies line H1. A high degree of polymorphism in the hybridization patterns was found, confirming the extensive variability present in H. chilense. This work provides tools for the identification of H. chilense chromosomes in different genetic backgrounds.
foxois required for resistance to amino acid starvation in Drosophila
Authors: Kramer Jamie M. , Slade Jennifer D. , Staveley Brian E.
Published: July 2008

The ability of an organism to alter its metabolism, growth, and reproductive capacity in response to fluctuations in food availability has likely been an important factor in the course of evolution. The insulin signalling pathway is an evolutionarily conserved mechanism used by metazoan animals to sense and respond to changes in nutrient intake. During conditions of starvation the level of circulating insulin is low. Under conditions of low insulin, the foxo family of transcription factors are activated. Studies in Drosophila suggest that Drosophila foxo may alter the transcriptional profile of cells to allow for maximum survival of the fly during starvation. We have tested this ability in transgenic flies containing a luciferase reporter gene under the control of foxo response elements. We show that foxo activity is increased during amino acid starvation and reduced in the presence of amino acids. In addition, we find that loss of function of foxo leads to reduced survival under conditions of amino acid starvation in both larvae and adult flies. These data provide direct evidence that foxo is activated during amino acid starvation and is critical for optimal survival under these conditions.
Chloroplast DNA diversity reveals the contribution of two wild species to the origin and evolution of diploid safflower (Carthamus tinctorius L.)
Authors: Sehgal Deepmala , Rajpal Vijay Rani , Raina Soom Nath
Published: July 2008

The identity of the wild progenitor of one of the most important oil crop species, Carthamus tinctorius (2n = 2x = 24), commonly known as safflower, has been the subject of numerous studies at morphological, biochemical, cytogenetic, and biosystematic levels, but no definitive conclusions have been made. The nuclear, mitochondrial, and chloroplast genomes of the two botanical varieties of C. tinctorius, C. tinctorius var. tinctorius and C. tinctorius var. inermis, and two wild species, C. palaestinus and C. oxyacantha , were assayed at the nucleotide sequence level and by DNA markers. The nuclear and mitochondrial DNA assays were not helpful in conclusively identifying the diploid ancestor of C. tinctorius. The chloroplast DNA diversity, on the other hand, unambiguously provided new and novel evidence that C. palaestinus and C. oxyacantha contributed their plastomes to the evolution of C. tinctorius var. inermis and C. tinctorius var. tinctorius, respectively. This study, therefore, affirms a startling revelation of a rare event of two wild species contributing to the origin and evolution of safflower, a major world oilseed crop about whose genetics very little is known.
Construction of a genetic linkage map of black gram,Vigna mungo(L.) Hepper, based on molecular markers and comparative studies
Authors: Gupta S. K. , Souframanien J. , Gopalakrishna T.
Published: July 2008

A genetic linkage map of black gram, Vigna mungo (L.) Hepper, was constructed with 428 molecular markers using an F9recombinant inbred population of 104 individuals. The population was derived from an inter-subspecific cross between a black gram cultivar, TU94-2, and a wild genotype, V. mungo var. silvestris. The linkage analysis at a LOD score of 5.0 distributed all 428 markers (254 AFLP, 47 SSR, 86 RAPD, and 41 ISSR) into 11 linkage groups. The map spanned a total distance of 865.1 cM with an average marker density of 2 cM. The largest linkage group spanned 115 cM and the smallest linkage group was of 44.9 cM. The number of markers per linkage group ranged from 11 to 86 and the average distance between markers varied from 1.1 to 5.6 cM. Comparison of the map with other published azuki bean and black gram maps showed high colinearity of markers, with some inversions. The current map is the most saturated map for black gram to date and will provide a useful tool for identification of QTLs and for marker-assisted selection of agronomically important characters in black gram.
Mapping of markers related to self-incompatibility, disease resistance, and quality traits inLolium perenneL.
Authors: Van Daele Inge , Muylle Hilde , Van Bockstaele Erik , Roldán-Ruiz Isabel
Published: July 2008

Several linkage maps, mainly based on anonymous markers, are now available for Lolium perenne . The saturation of these maps with markers derived from expressed sequences would provide information useful for QTL mapping and map alignment. Therefore, we initiated a study to develop and map DNA markers in genes related to self-incompatibility, disease resistance, and quality traits such as digestibility and sugar content in two L. perenne families. In total, 483 and 504 primer pairs were designed and used to screen the ILGI and CLO-DvP mapping populations, respectively, for length polymorphisms. Finally, we were able to map 67 EST markers in at least one mapping population. Several of these markers coincide with previously reported QTL regions for the traits considered or are located in the neighbourhood of the self-incompatibility loci, S and Z. The markers developed expand the set of gene-derived markers available for genetic mapping in ryegrasses.
Axial load transfer for piles in sand. I. Tests on an instrumented precast pile
Authors: Altaee Ameir , Fellenius Bengt H. , Evgin Erman
Published: July 2008

A precast concrete pile was driven 11.0 m into a sand deposit and subjected to three compression and one tension static loading tests. By means of strain-gage instrumentation, the loads imposed in the pile during the tests were determined. The observed load distributions appeared to suggest the existence of a critical depth. However, when the load data were supplemented with the residual load acting before the start of the tests, the appearance of critical depth disappeared. Instead, the analysis of the tests showed that the load distribution was a function of the effective overburden stresses in the soil over the full pile length, with β-ratios ranging from 0.40 through 0.65 and a toe bearing coefficient of 30. The shaft resistance degraded slightly from test to test. The shaft resistance in tension was about equal with the shaft resistance in compression. The β-ratios and the toe bearing coefficient derived from the test were applied unchanged to the results of compression tests on a second test pile, a 15 m long identical pile, and the calculated capacity agreed with the capacity found in the static loading test. Key words : instrumented pile, sand, loading test, residual load, load transfer.
Energy dissipation and dynamic behaviour of clay under cyclic loading
Authors: Cao Y. L. , Law K. T.
Published: July 2008

A laboratory study has been conducted to investigate the dynamic behaviour of Champlain Sea clay from two locations in the Ottawa River valley region. The test program includes cyclic triaxial tests and resonant-column tests. The soil samples were consolidated at a range of pressures before the dynamic shear in order to cover the dynamic behaviour under both the overconsolidated and the normally consolidated states. An energy concept is introduced to interpret the test results. Mathematical relationships have been established for describing the various aspects of dynamic behaviour. These aspects include excess pore pressure, dynamic strength, dynamic shear modulus, and plastic strain. The study shows that the energy concept provides a promising way to analyze dynamic soil behaviour. Key words : energy, dynamic behaviour, clay, cyclic test, earthquake, excess pore pressure, shear modulus, strength.
Field measurement of anchor forces, ground temperatures, and pore-water pressures behind a retaining structure in northwestern Ontario
Authors: Eigenbrod K. D. , Burak J. P.
Published: July 2008

Anchor forces, ground temperatures, and piezometric pressures were measured at a retaining wall in northwestern Ontario over a period of 2 years. The anchor forces were measured with strain gauges attached in pairs directly to the anchor rods. This method appeared practical in the field for time periods of less than 2 years as long as the strain gauges were carefully protected against moisture. The anchor forces increased from an average of 5 kN initially up to values of 50 kN during the winter periods and dropped during the summer periods back to the same values measured initially. The anchor forces were largely independent of pore-water pressure variations behind the wall. Rapid drawdown conditions, however, which were experienced during the second summer, were reflected in a load increase that was equivalent to the associated unloading effect in front of the wall. The pore-water pressures behind the wall were not noticeably affected by rapid drawdown, possibly due to the restraining effect of the anchors and the high rigidity of the low sheet pile wall. Ground temperatures at or below the groundwater table never dropped below 0 °C thus restricting the depth of frost penetration. Key words : anchor loads, freezing pressure, retaining walls, pore-water pressures, ground temperatures, field measurements.
Slope failures associated with the 1988 Saguenay earthquake, Quebec, Canada
Authors: Lefebvre Guy , Leboeuf Denis , Hornych Pierre , Tanguay Luc
Published: July 2008

Nine case records of slope failure during the Saguenay earthquake are documented, including five in granular embankments, two in natural slopes in granular material with small embankments at the top, and two in sensitive clay. The bedrock motion during the earthquake is well documented; each failure is related to the most probable bedrock motion at the site (0.05 to 0.15 g). For the seven cases of failure in granular slopes, the reserve of stability under static conditions was relatively low before the earthquake, and only a small additional undrained loading was necessary to develop failure. Two slope failures occurred in extrasensitive clay deposits containing no visible lens or layer of silt or sand. Silty or sandy materials have been identified only at the clay–till contact. It is believed that in at least one of the sites a portion of the failure surface developed at the inclined clay–till contact. Key words : slope failure, earthquake, sensitive clays, embankment fill, stability, granular material.
Effets du gel sur les infrastructures routières argileuses au Québec
Authors: Roy Marius , Tardif Jean , Leroueil Serge , Larose Gaston , Rochelle Pierre La
Published: July 2008

This study deals with the freeze and thaw effects on the mechanical behaviour of the clayey subgrades exposed by cuts for the placement of road foundations. Twelve cut sites have been analysed in cooperation with the ministère des Transports du Québec. As damages were observed after the first winter on some of the sites, whereas none were apparent on other sites, it was possible to define the factors that may lead to such damages. In particular, the field study confirms the laboratory results showing that criteria based on liquidity index are sufficient to characterize the change of mechanical behaviour of the clayey soils subjected to one freeze–thaw cycle. Key words : clay, liquidity index, freeze-thaw, bearing capacity of roads, heaving, cut. [Translated by the Journal]
Effect of microcracking on the deformation of ice
Authors: Jordaan Ian J. , Stone Barry M. , McKenna Richard F. , Fuglem Mark K.
Published: July 2008

Tests in the field and full-scale experience with arctic structures show that the crushing of ice is accompanied by large fluctuations in load. Field experiments show that, in addition to variations of load in time, significant spatial variations across the contact surface also occur. The deformation is observed to take place in a thin layer of damaged ice, which appears near the structure or indenter surface. It is important to model the deformation and strength of ice in this zone. Various aspects of modelling are discussed in the paper, in particular, measures of damage and the relation to the deformation of ice. The relevance of various components of deformation (elastic, viscous, delayed elastic) is outlined, and two mathematical formulations for the deformation are discussed. The behaviour was investigated by a series of tests at constant strain rate as well as tests in which the strain response to stress of damaged and undamaged ice was measured. The creep rate in damaged ice is shown to be significantly enhanced, even for short-term loading. Comparisons of theory and experiment are given for constant strain-rate tests. The models have been calibrated to the experimental data described in the paper. It is a matter for future research to generalize the models to all damage levels and stress states. Key words : creep, damage, deformation, ice, microcracking, visco-elasticity.
Large-scale mass-wasting events on the Fraser River delta front near Sand Heads, British Columbia
Authors: McKenna G. T. , Luternauer J. L. , Kostaschuk R. A.
Published: July 2008

Although the Fraser River delta front supports coastal structures including ports, a lighthouse, jetties, submarine power cables, and sewage pipelines, the stability of the delta front is little understood. Five large-scale mass-wasting events at the mouth of the Main Channel near Sand Heads have been detected by comparing successive bathymetric surveys conducted by Public Works Canada between 1970 and 1986. These events can involve the downslope movement of more than 1 × 106 m3 of silty sand and the landward retrogression of the delta-front crest of up to 350 m or more. Morphologic and sedimentologic evidence suggests that these events are slope failures which result from the liquefaction of silty sand. Rapid deposition at the river mouth is likely a prerequisite for failure, although interstitial gas, tidal currents, waves, and earthquakes also may contribute to failure. These results have important implications for the foundation stability of the Sand Heads Lighthouse and future coastal structures in the area. Key words : bathymetry, mass wasting, liquefaction, hazard, Fraser River delta.
Shear modulus of cohesionless soil: variation with stress and strain level
Authors: Fahey Martin
Published: July 2008

The value of the secant shear modulus (G) of sand measured in cyclic tests reduces as the amplitude of cycling increases. As a first approximation, it is assumed that the curve joining the extreme points of stress–strain (τ–γ) loops of different amplitudes (a so-called "backbone curve") is hyperbolic. The shear strength (τmax) of sand is directly proportional to the mean effective confining pressure (p′), whereas the maximum shear modulus (G0) is proportional to (p′)n, with n being between 0.4 and 0.5. Based on these assumptions, it is shown that at the same shear strain level, different G/G0 values should be expected at different p′ values. One of the features of a hyperbolic τ–γ curve is that there is a unique linear relationship between G/G0 and normalized shear stress level (defined as τ/τmax), independent of p′. Therefore, considering the normalized shear stress level rather than the shear strain level may be a more logical and unifying way of examining the variation in G/G0. Key words : shear modulus, hyperbolic stress–strain curve, pressuremeter test.
One-dimensional consolidation with uncertain properties
Authors: Hong Han Ping
Published: July 2008

Different reasonable probability distributions can be assigned for the coefficient of consolidation, C. But if no more than the first few probability moments of the excess pore pressure and of the degree of consolidation which are functions of C are of concern, it is advantageous to use a simpler, distribution-free method for matching probability moments of C. In this note, the method of discretization of probability is used to analyze one-dimensional consolidation. The solutions, influenced by the probability moments of third, fourth, and fifth order of C, are presented. Key words : probability, discretization, coefficient of consolidation, excess pore pressure, degree of consolidation, moments, random variable.
Variation in the seasonal selection of resources by woodland caribou in northern British Columbia
Authors: Gustine D. D. , Parker K. L.
Published: July 2008

Conservation planning for species of concern or importance can be aided by resource selection functions (RSFs) that identify important areas or attributes. Models that can be interpreted biologically and provide reasonable predictive capacity may best be based on data from individuals grouped into seasonal selection strategies for particular geographical areas or similarities in topographical and vegetative associations. We used logistic regression, the information–theoretic approach, satellite imagery, and locational data (n = 31 females; 16 803 locations) from global positioning system (GPS) collared woodland caribou ( Rangifer tarandus caribou (Gmelin, 1788)) to model resource selection by animals during calving, summer, fall, breeding, winter, and late-winter seasons. Higher variation in resource use corresponded to times when caribou and their young were most susceptible to predation or when food resources were limited. Even with multiple selection strategies, caribou followed a general progression from higher to lower elevation habitats from calving and summer to late winter. Caribou selected against or completely avoided the burned–disturbed vegetation class in every season except summer. We incorporated RSFs with a raster geographic information system to create selection landscapes. We validated selection landscapes using withheld GPS data (n = 6077), 50 known calving sites, and Spearman’s rank correlation coefficient. Selection models and final selection landscapes performed well in validating use locations of woodland caribou in all seasons (all P < 0.003) and in predicting known calving sites (P < 0.001). When seasonal selection strategies are identified and models are coupled with validation, RSFs are effective tools to assist in conservation planning.
Effect of seasonal changes in upwelling activity on the foraging locations of a wide-ranging central-place forager, the New Zealand fur seal
Authors: Baylis A. M.M. , Page B. , Goldsworthy S. D.
Published: July 2008

Lactating New Zealand fur seals ( Arctocephalus forsteri (Lesson, 1828)) that breed at Cape Gantheaume, South Australia, experience broad-scale seasonal changes in ocean productivity. To assess how seasonal changes in ocean productivity influenced foraging behaviour, 18 lactating New Zealand fur seals were fitted with satellite transmitters and time–depth recorders (TDRs). Using temperature and depth data from TDRs, we used the presence of thermoclines as a surrogate measure of upwelling activity in continental-shelf waters. During the austral autumn 80% of lactating fur seals foraged on the continental shelf (114 ± 44 km from the colony), in a region associated with the Bonney upwelling. In contrast, during winter months seals predominantly foraged in oceanic waters (62%), in a region associated with the Subtropical Front (460 ± 138 km from the colony). Our results indicate that lactating New Zealand fur seals shift their foraging location from continental-shelf to oceanic waters in response to a seasonal decline in productivity over the continental shelf, attributed to the cessation of the Bonney upwelling. This study identified two regions used by lactating New Zealand fur seals: (1) a nearby and seasonally productive upwelling system and (2) a distant and permanent oceanic front.
Expanding the horizon: the Red Queen and potential alternatives
Authors: Tobler M. , Schlupp I.
Published: July 2008

The Red Queen hypothesis (RQH) is one of the most widely accepted hypotheses explaining the persistence of sexual reproduction despite its costs. It posits that sexual species, compared with asexuals, are more adept at countering parasites, because their per-generation recombination rate is higher. Despite theoretical support, current empirical studies have failed to provide unanimous support. Here, we suggest that future tests of the RQH should more thoroughly elucidate its underlying assumptions and potential alternative hypotheses. While the RQH predicts that negative frequency-dependent selection shapes host–parasite interactions, differences between sexuals and asexuals are potentially important. Key assumptions about asexual species and their sexual close relatives include (i) ecological and behavioral traits are similar, (ii) among-individual genetic diversity is greater in sexuals than in asexuals, and (iii) within-individual genetic diversity is similar in asexuals and sexuals. We review current evidence for the RQH, highlight differences between asexual and sexual species and how those differences might translate into differential responses to parasite infections, and discuss how they can influence the results and interpretation of empirical studies. Considering differences between asexual and sexual species in future tests of the RQH will help to refine predictions and eliminate alternative hypotheses.
Intersexual variation in the seasonal behaviour and depth distribution of a freshwater temperate fish, the largemouth bass
Authors: Hanson K. C. , Hasler C. T. , Cooke S. J. , Suski C. D. , Philipp D. P.
Published: July 2008

Because fish are poikilothermic, water temperature is regarded as a primary factor influencing their activity and behaviour. Rarely have field studies been conducted with the spatiotemporal resolution to enable rigorous quantitative assessments of that relationship. Furthermore, there have been few studies that have considered the influence of sex on the seasonal behaviour of fish. Twenty largemouth bass ( Micropterus salmoides (Lacepède, 1802)) were implanted with coded acoustic telemetry transmitters and remotely tracked in near real time in a small lake in Ontario, Canada, via a whole-lake hydrophone array between 1 November 2004 and 30 September 2005. Fish inhabited the deepest waters and were least active during the winter months under ice. During the warmest months, fish were most active and inhabited the littoral zone. Sex-specific differences were noted year-round. Reproductive males were less active and inhabited shallower depths during the spawning and post-reproductive periods. Reproductive males inhabited the deepest depths during winter and fall, with nonreproductive males at the shallowest depths. Throughout the year, the behaviour of nonreproductive males and females was similar. While differences in behaviour of bass are primarily driven by water temperature, sex and reproductive status play important roles year-round, especially during and after the reproductive period.
Pupping-site fidelity among individual Steller sea lions (Eumetopias jubatus) at Chiswell Island, Alaska
Authors: Parker P. , Harvey J. T. , Maniscalco J. M. , Atkinson S.
Published: July 2008

Pupping-site fidelity (defined as pupping within 5.8 m of a previous location in ≥2 years) in Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) was investigated during the breeding seasons from 2001 to 2005 at Chiswell Island, a small rookery in the Gulf of Alaska. Density of females was minimal with 54–80 pups born. Photo-identification of individuals and GPS points, including elevation of the rookery, were used to determine locations of 297 births. Sixty-four percentage (35/55) of the females exhibited pupping-site fidelity, and mean frequency of site fidelity was greater for females that gave birth >3 times. Fifty percentage of the births occurred at 22% of the locations for all years, indicating that multiple births occurred at some locations throughout the breeding season. Competition or aggression among females for specific pupping locations before birth was not observed, and there was no temporal order of pupping locations used, indicating that the rookery was not overcrowded and that many suitable pupping locations existed. Multiparous females gave birth at significantly greater distances from the surf zone than primiparous females. Long-term monitoring of pupping-site fidelity in combination with other measures of maternal care will ultimately determine which factors have the greatest effect on pup survival.
Cyclic dynamics of sympatric lemming populations on Bylot Island, Nunavut, Canada
Authors: Gruyer Nicolas , Gauthier Gilles , Berteaux Dominique
Published: July 2008

We characterized the fluctuations (amplitude, periodicity) of two sympatric species, the brown lemming ( Lemmus sibiricus (Kerr, 1792)) and the northern collared lemming ( Dicrostonyx groenlandicus (Traill, 1823)), in a High Arctic area. Our objective was to determine if these populations were cyclic, and if fluctuations in numbers were synchronized between the two species temporally and spatially. An annual index of lemming abundance was obtained using snap-traps at two sites 30 km apart on Bylot Island (Nunavut, Canada) over 13 years (1993–2005) and 9 years (1997–2005), respectively. The time series were analyzed by spectral analyses and autoregressive modelling. At the site with the longest record, brown lemming showed regular population fluctuations of large amplitude (>40-fold), but collared lemming fluctuations were of much smaller amplitude (4-fold). At the other site, the collared lemming population was higher than at the main site, but brown lemmings were still most abundant in the peak year. Models with a second-order function obtained from a spectral analysis were highly correlated with the observed abundance index in both species at the site with the longest time series, and provide evidence of cyclic dynamic. The periods of the cycles were estimated at 3.69 ± 0.04 (SE) years for brown lemmings and 3.92 ± 0.24 (SE) years for collared lemmings, but the amplitude of the cycle was weak in the latter species. Fluctuations in abundance at the same site were relatively well synchronized between the two species, but the evidence for synchrony between sites was equivocal.
Genetic diversity and structure in Canadian northern leopard frog (Rana pipiens) populations: implications for reintroduction programs
Authors: Wilson G. A. , Fulton T. L. , Kendell K. , Scrimgeour G. , Paszkowski C. A. , Coltman D. W.
Published: July 2008

The northern leopard frog ( Rana pipiens Schreber, 1782) underwent a large decline in the western portion of its range and only occurs in 20% of historically occupied sites in Alberta. Its absence may reflect an inability to disperse to these sites because of habitat fragmentation, and human-mediated translocation has been proposed. In this study, we used three criteria to examine the genetic suitability of potential translocation sources: diversity, similarity to area of reintroduction, and evolutionary history. We genotyped 187 samples and sequenced 812 bp of the mitochondrial NADH dehydrogenase 1 gene from 14 Canadian northern leopard frog populations. Nuclear and mitochondrial diversity were highest in Manitoba and western Ontario and declined westward. There was no significant relationship between genetic and geographic distance, suggesting that genetic drift is a driving force affecting the genetic relationships between populations. Regions separated by more than ~50 km were quite differentiated. Therefore, source populations similar to the original inhabitants of an area for reintroduction may be uncommon. Mitochondrial analyses revealed that all populations share a close evolutionary history, belonging to the western haplotype group. While genetic criteria support the use of Manitoba and Ontario as sources, the desirability of environmental similarity to the reintroduction site suggests that ecologically exchangeable Alberta populations should also be considered.
Avoidance responses to scents of snakes that pose different risks of predation by adult natterjack toads, Bufo calamita
Authors: Gonzalo Adega , López Pilar , Martín José
Published: July 2008

Many antipredator behaviors are mediated by the ability of prey to recognize chemical cues from predators. Adult amphibians mainly use vision to detect predators, but the ability to detect chemicals of predators and conspecifics could be advantageous, especially when assessing safety of potential refuges where the use of visual cues is limited. We analyzed in the laboratory whether refuge choice by adult natterjack toads ( Bufo calamita Laurenti, 1768) was influenced by the presence in the refuge of chemical cues from conspecifics or from two different snake predators ( Natrix maura (L., 1758) and Natrix natrix (L., 1758)). Natterjack toads avoided refuges scented by snakes and spent less time in refuges with snake scent than in refuges with conspecific scent. Toads also seemed to have different hiding behaviors depending on the snake species that they found. We concluded that adult natterjack toads were able to recognize and avoid chemical cues of dangerous snakes, but it was not clear whether toads discriminated between chemicals of the two snake species, even though these two snakes might pose different risks of predation.
Why do female Columbian ground squirrels (Spermophilus columbianus) give an estrus call?
Authors: Manno T. G. , Nesterova A. P. , DeBarbieri L. M. , Dobson F. S.
Published: July 2008

Female Columbian ground squirrels ( Spermophilus columbianus (Ord, 1815)) sometimes emit a repetitive vocalization after copulation. We examined two possible explanations for why sexual selection would favor expression of these “estrus calls”: to encourage sperm competition through mating with additional males and to increase mate guarding by the consort male as a mechanism of postcopulatory female mate choice. During three annual mating periods, we observed mating behaviour, estrus calls, and postcopulatory behavioural interactions of free-ranging individuals. Predictions of the advertisement hypothesis were supported, as females typically solicited courtship interactions with nonconsort males directly after emitting an estrus call. Thus, females that emitted an estrus call were more likely to acquire additional matings than noncalling females, particularly if calls were emitted after the female’s first mating. These results were not consistent with predictions of the postcopulatory female mate choice hypothesis, as calling females should initiate social contact with the consort male and stay proximate to the copulatory site after copulation if they are encouraging mate guarding. For reasons that remain unclear, the probability that an estrus call would follow mating increased linearly with the age of the consort male. However, our results taken together suggest that estrus advertisement is the most likely social context of female postcopulatory calling.
The effect of constant and fluctuating incubation temperatures on the phenotype of black ratsnakes (Elaphe obsoleta)
Authors: Patterson L. D. , Blouin-Demers G.
Published: July 2008

According to the maternal manipulation hypothesis, females manipulate the phenotypes of their offspring by selecting favourable incubation conditions. In oviparous black ratsnakes ( Elaphe obsoleta Say in James, 1823), females manipulate offspring phenotype through nest-site selection. This study aimed to determine whether the thermal mean and variance of the incubation regime affect fitness-related traits in hatchlings. We incubated 136 eggs in a split-clutch design at two thermal means (26 and 29 °C) and variances (constant and ±3 °C). Hatchlings incubated at higher temperatures hatched earlier, were longer, faster, and less defensive. Hatchlings incubated at constant temperatures hatched earlier and were longer. For athletic performance, there was a significant interaction between temperature mean and variance: hatchlings incubated at 29 °C swam faster, had a lower muscular strength, and righted themselves equally fast when incubated at constant temperatures, whereas hatchlings incubated at 26 °C were stronger, swam faster, and righted themselves more slowly. Overall, constant incubation temperatures produced hatchlings with phenotypes favouring higher survival than fluctuating temperatures, but the effect of thermal variance was not as pronounced as the effect of thermal mean. Therefore, we found some support for the hypothesis that black ratsnakes prefer communal over single-female nests because communal nests have higher, more constant temperatures.
Correlates of postfledging survival, the timing of dispersal, and local recruitment in American Dippers
Authors: Middleton Holly A. , Green David J.
Published: July 2008

Natal dispersal is a complex process that involves decisions about when to leave the natal territory, how to move through the landscape, and where to settle. We investigated what factors influence the timing of dispersal and local recruitment of American Dippers ( Cinclus mexicanus Swainson, 1827) in Chilliwack, British Columbia. We monitored 102 fledglings from 30 broods between 2003 and 2005. Survival to 5 days after fledging was high (>80%), but individuals fledging early in the season and at an older age had higher survival than those fledging later and younger. Fifty-four percentage of surviving fledglings dispersed within 14 days of nest departure. Females and individuals that spent more time foraging were more likely to disperse within 14 days than males and individuals that foraged less. For those that dispersed, individuals that fledged early in the season and at older ages spent less time in their natal territory. Approximately 10% (10/82) of dispersing individuals were known to recruit locally. Local recruitment of individuals that delayed dispersal was higher than local recruitment of individuals dispersing early. Our study demonstrates that fitness benefits associated with extended natal philopatry are not restricted to cooperatively breeding birds.
THE KEY ROLE OF SHORTCUTS OF SMALL-WORLD NETWORK IN OPINION FORMATION
Authors: GUO LONG , CAI XU
Published: July 2008

In this paper, we analyze the average magnetization and spatial correlation of opinion formation in small-world network and in the regular lattice. We construct NW small-world network through adding shortcuts on the regular lattice. With computer simulation, we find that there exists short- and long-range spatial correlation of the average magnetization m(t) in NW small-world network and the evolution trend of opinion is dependent on the initial opinion condition by comparing with that in regular lattice. On the other hand, we analyze the average magnetization m(t) using the time series analysis, and find the Hurst exponent H ≃ 0.5 in NW small-world network and H = 0 in regular lattice. All the results show the important role of shortcuts in the NW small-world network, which reflects some interesting aspects in our real society indirectly.
THE INVESTIGATION OF THE TRAFFIC FLOW BEHAVIOR IN TOLLBOOTHS USING CELLULAR AUTOMATON MODEL
Authors: JETTO K. , EZ-ZAHRAOUY H. , BENYOUSSEF A.
Published: July 2008

Tollbooths are used to collect tolls and to control traffic flow. However, the presence of these tollbooths will slow down traffic, especially in heavily traveled roads. As a consequence, drivers and goods will spend more time and fuel waiting in a long queue. Unfortunately, there are a few papers in the literature, which have been addressed the effect of tollbooths on the traffic flow; whereas in this paper is, the properties of traffic flow inside the tollbooths are investigated. The proposed cellular automaton traffic model, with open boundaries, is based on some changing lane rules, which are inspired on the situations inside the toll plaza. The vehicles enter the plaza with an injecting rate α, and they leave with an extracting rate β, which is inversely proportional to the time service Tw. The simulation results show the existence of three phases in the phase diagram (α, β), namely: the low density phase, the congested phase, and the jamming phase. Furthermore, it is found that the vehicles does not spend the same time Tmin the plaza, even if they have the same time service. This analysis states clearly that the existence of the congested phase and the fluctuation Tmare due to the non-zero values of the probability P of changing the lane. Such phenomena disappear when P = 0, i.e., the drivers move without changing their lane. In other words, the human behavior (spontaneous changing lanes) is responsible for the congestion observed in the tollbooth.
PHASE TRANSITION IN SEXUAL REPRODUCTION AND BIOLOGICAL EVOLUTION
Authors: ZAWIERTA MARTA , WAGA WOJCIECH , MACKIEWICZ DOROTA , BIECEK PRZEMYSŁAW , CEBRAT STANISŁAW
Published: July 2008

Using Monte Carlo model of biological evolution it is discovered that populations can switch between two different strategies of their genomes' evolution: Darwinian purifying selection and complementing the haplotypes. The first one is exploited in the large panmictic populations while the second one in the small highly inbred populations. The choice depends on the crossover frequency. There is a power law relation between the critical value of crossover frequency and the size of panmictic population. Under constant inbreeding this critical value of crossover does not depend on the population size and has a character of phase transition. Close to this value sympatric speciation is observed.
EXPLICIT EIGHTH ORDER NUMEROV-TYPE METHODS WITH REDUCED NUMBER OF STAGES FOR OSCILLATORY IVPs
Authors: Th. FAMELIS I.
Published: July 2008

Using a new methodology for deriving hybrid Numerov-type schemes, we present new explicit methods for the solution of second order initial value problems with oscillating solutions. The new methods attain algebraic order eight at a cost of eight function evaluations per step which is the most economical in computational cost that can be found in the literature. The methods have high amplification and phase-lag order characteristics in order to suit to the solution of problems with oscillatory solutions. The numerical tests in a variety of problems justify our effort.
SAND DENSITY AS SANDPILE DESCRIPTOR
Authors: SHAPOVAL A. B. , SHNIRMAN M. G.
Published: July 2008

We investigate a collection of one-parametric families of isotropic sandpile models. The models involve the square lattice slowly accumulating the grains and quickly transferring them as the local piles become over-critical. The paper groups the sand-piles with respect to two features influencing the model dynamics. They are the value of the local transfer's stochasticity and the number of the transferred grains. Every pair generates one-parametric family of the sand-piles. The parameter reflects the relative height of an over-critical pile with respect to the incoming flow of sand. If the stochasticity disappears with the growth of the parameter, the families with the fixed number of the transferred grains have much in common with Bak et al.'s sand-pile [Phys. Rev. Lett.59, 381 (1987)], while the families, whose over-critical piles lose all their grains, tend to the Zhang sand-pile [Phys. Rev. Lett.63, 470 (1989)]. The families with non-disappearing variance give rise to new properties described in terms of the probability distribution of the pile heights.
RISK-SEEKING VERSUS RISK-AVOIDING INVESTMENTS IN NOISY PERIODIC ENVIRONMENTS
Authors: NAVARRO-BARRIENTOS J. EMETERIO , WALTER FRANK E. , SCHWEITZER FRANK
Published: July 2008

We study the performance of various agent strategies in an artificial investment scenario. Agents are equipped with a budget, x(t), and at each time step invest a particular fraction, q(t), of their budget. The return on investment (RoI), r(t), is characterized by a periodic function with different types and levels of noise. Risk-avoiding agents choose their fraction q(t) proportional to the expected positive RoI, while risk-seeking agents always choose a maximum value q max if they predict the RoI to be positive ("everything on red"). In addition to these different strategies, agents have different capabilities to predict the future r(t), dependent on their internal complexity. Here, we compare "zero-intelligent" agents using technical analysis (such as moving least squares) with agents using reinforcement learning or genetic algorithms to predict r(t). The performance of agents is measured by their average budget growth after a certain number of time steps. We present results of extensive computer simulations, which show that, for our given artificial environment, (i) the risk-seeking strategy outperforms the risk-avoiding one, and (ii) the genetic algorithm was able to find this optimal strategy itself, and thus outperforms other prediction approaches considered.