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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 54 (1979), S. 225-233 
    ISSN: 1432-2242
    Keywords: Heliothis virescens ; Genetic control ; Population model ; Hybrid sterility ; Tobacco budworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A model was developed which corrects and extends an earlier one proposed for the control of the tobacco budworm, Heliothis virescens (F.), through hybrid male sterility. Population suppression is effected through the release into natural populations of the backcross progeny of a hybrid between H. virescens and a related species. Thereafter, the system perpetuates itself in nature through continual backcrossing of the fertile backcross females to native H. virescens males. When the proportion of backcross hybrid females in the total population is large enough to draw off the insemination potential of the native males, the native females fail to replace themselves. The present model demonstrated that the ratio of released backcross hybrids to natural H. virescens remains constant in a closed population. Furthermore it was shown that the release ratio necessary to achieve extinction of a closed population is related to the number of females that a male can inseminate and to the population growth rate. Release ratios required to slow natural population growth and to lessen the impact damage of releases on crop plants were also examined. Effects of selection against the backcross females on the predictions of the model were explored.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9071
    Keywords: Mitochondrial DNA ; RFLP ; Leptinotarsa decemlineata ; Colorado potato beetle ; population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study demonstrates variability in restriction enzyme cleavage sites of mitochondrial DNA (mtDNA) among four popalations of Colorado potato beetle (CPB). A suite of three enzymes (EcoRI,HpaI,PstI) was sufficient to discriminate among the populations tested. Individuals heteroplasmic for restriction enzyme patterns were found in some populations. Variability in CPB mtDNA should prove useful in efforts to trace the origin and dispersal of the species in North America.
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  • 3
    Publication Date: 2017-03-10
    Description: Filtration of planktonic algal cells from the water column into permeable sublittoral sediment and the fate of the cells in the shallow sands were studied during a red tide produced by the dinoflagellate Peridinella catenata at Hel Peninsula/Baltic in May 2004. Advective porewater flows associated with ripple topography of the bed caused rapid transport of algal cells down to 5 cm sediment depth. Sedimentary concentrations of algal cells mirrored algal concentrations in the overlying water column with increases and decreases within the upper 3 cm of the bed occurring within a few hours. Sedimentary algal uptake and release significantly differed between stations only 15 m laterally apart. Laboratory sediment-column experiments with 13C-labeled algal cells revealed algal decomposition at rates of up to 0.2% 13C h–1 in percolated sands originating from the study site. This was 2 orders of magnitude lower than observed decreases in sediment algal cell C abundance of up to 23% C h–1 after a drop in cell concentrations in the water column. Because bioturbation and ripple migration were negligible, we conclude that advective flushing of the uppermost sediment layer could rapidly remove cells from the sediment. Our results demonstrate close spatial and temporal coupling between algal cell concentrations in the boundary layer and those in the upper 6 cm of permeable sand sediment, and suggest that permeable beds can act as short-term storage buffer for phytoplankton. During passage through the sediment, planktonic algae may benefit from the higher nutrient concentrations available in the porewater.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 4
    Publication Date: 2017-03-10
    Description: Insight in the biogeochemistry and ecology of sandy sediments crucially depends on a quantitative description of pore water flow and the associated transport of various solutes and particles. We show that widely different problems can be modelled by the same flow and tracer equations. The principal difference between model applications concerns the geometry of the sediment-water interface and the pressure conditions that are specified along this boundary. We illustrate this commonality with four different case studies. These include biologically and physically induced pore water flows, as well as simplified laboratory set-ups versus more complex field-like conditions: [1] lugworm bio-irrigation in laboratory set-up, [2] interaction of bio-irrigation and groundwater seepage on a tidal flat, [3] pore water flow induced by rotational stirring in benthic chambers, and [4] pore water flow induced by unidirectional flow over a ripple sequence. The same two example simulations are performed in all four cases: (a) the time-dependent spreading of an inert tracer in the pore water, and (b) the computation of the steady-state distribution of oxygen in the sediment. Overall, our model comparison indicates that model development for sandy sediments is promising, but within an early stage. Clear challenges remain in terms of model development, model validation, and model implementation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 5
    Publication Date: 2017-03-06
    Description: This paper presents a new non-invasive technique for measuring sediment O2 uptake that, in its concept, differs fundamentally from other methods used to date. In almost all natural aquatic environments, the vertical transport of O2 through the water column toward the sediment surface is facilitated by turbulent motion. The new technique relies on measuring 2 parameters simultaneously and at the same point in the water above the sediment: the fluctuating vertical velocity using an acoustic Doppler velocimeter and the fluctuating O2 concentration using an O2 microelectrode. From these 2 parameters, which typically are measured 10 to 50 cm above the sediment surface for a period of 10 to 20 min and at a frequency of 15 to 25 Hz, the vertical flux of O2 toward the sediment surface is derived. Based on measurements performed under actual field conditions and comparisons with in situ flux-chamber measurements, we believe that this new technique is the optimal approach for determining O2 uptake by sediments. The technique is superior to conventional methods as measurements are done under true in situ conditions, i.e. without any disturbance of the sediment and under the natural hydrodynamic conditions. Furthermore, this technique can be used for bio-irrigated or highly permeable sediments, such as sands, where traditional methods often fail. While this paper only focuses on O2 uptake by sediments, the technique can also be applied to other solutes that can be measured at a sufficiently high temporal resolution.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 6
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A numerical investigation has been undertaken to characterize the axisymmetric laminar flow generated by a rotating disk inside a cylinder with an open top, containing a viscous fluid above as layer of fluid-saturated porous medium. The mathematical model is based on a continuum approach for both fluid and porous regions. Attention is focussed on conditions favouring steady, stable, axisymmetric solutions of the Darcy-Brinkman-Lapwood equation. The accuracy of the method is verified by solving some vortex flow problems in disk-cylinder geometries and comparing the results with: (a) existing numerical solutions and, (b) experimental pressure measurements in a similar geometry. Calculations are performed to investigate the fluid exchange between the porous region (porewater) and the overlying water. Results indicate that flow through composite (fluid-sediment) systems can be handled with good accuracy by the method presented here. With our approach the magnitude of advective porewater transport in sediments may be predicted. This finding is important for improved designs of flux chambers and also for understanding advective transport phenomena.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] An interesting underwater landscape created by the mud shrimp, Callianassa truncata, was found in a shallow bay off the coast of the Italian island, Giglio, in the Mediterranean Sea (Fig. 1). Conspicuous mounds and funnels covered the sea bed at an average density of 120 mounds per square metre ...
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  • 8
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Thioploca mats, sediment and water chemistry were studied along a shelf transect off the Chilean coast during late summer, March 1994 (Fig. 1). In the densest Thioploca mat, at 87m water depth, the wet weight of sheathed Thioploca reached nearly 1 kg m2, of which the total bacterial ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-8248
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Les insectes élevés au laboratoire et destinés à être utilisés dans des programmes de lutte biologique doivent présenter des comportements similaires à ceux des insectes sauvages. De façon à étudier les modifications de comportement ainsi que les adaptations aux conditions d'élevage, deux souches de la Mouche antillaise des fruitsAnastrepha suspensa (Loew) ont été comparées. L'une recueillie dans la nature et l'autre adaptée aux conditions d'élevage ont été suivies pendant 5 générations au cours desquelles ont été étudiés la fertilité des œufs, le poids et le nombre de pupes formées, la longévité, le sex-ratio, la fréquence des accouplements, la fécondité et la production de CO2 chez les insectes parfaits. Pendant les 5 génerations les insectes issus de la nature ont présenté par rapport aux insectes d'élevage une fécondité réduite de 51% une durée de développement supérieure de 16% et une production de CO2 pendant la photophase diminuée de 16%.
    Notes: Abstract Insects that are colonized for use in biological control programs must be behaviorally functional with respect to target field populations. To quantify adaptation during colonization and identify some of the behavioral changes that occur during the process, comparable colonies of field-collected and laboratory-adapted Caribbean fruit flies,Anastrepha suspensa (Loew) were monitored through 5 generations for fertility of eggs, weights and yields of pupae, and viability, sex ratio, insemination frequency, fecundity and CO2 production of adults. After five generations, the wild strain still produced 57% fewer eggs, required 6–7 extra days per cycle (16% longer), and produced 16% less CO2 per generation
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 14 (1988), S. 2047-2061 
    ISSN: 1573-1561
    Keywords: 11-Tetradecenyl acetate ; population genetics behavioral genetics ; Ostrinia nubilalis European corn borer ; Lepidoptera ; Pyralidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The sex pheromone communication system of the European corn borer moth varies intraspecifically. Analyses of pheromonal extracts of wild females, collected in a region where the types (each producing a different isomeric proportion ofZ- andE-11-tetradecenyl acetate) are sympatric, showed that theZ pheromone-production allele frequency was ca. 4 times greater than theE allele. The paucity ofE production and response alleles in the population indicates that moths inheriting those alleles concomitantly inherit some undefined disadvantage. The types interbreed, but the frequency of heterozygous pheromone-production types among wild females was less than predicted by Hardy-Weinberg equilibrium and was evidence of positive assortative mating. Rates of male captures in field traps baited with females of the three pheromonal types also evidenced assortative mating in the population. Progeny tests with males captured in the traps provided circumstantial evidence that pheromone response and production functions in the species are regulated by separate genetic loci and that the loci are not always complementary; i.e., a male can carry an allele coding for production of one pheromonal isomer ratio but can be genetically predisposed to respond to another.
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