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  • Springer  (401)
  • 2020-2022  (69)
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  • 2015-2019  (283)
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  • 1
    Electronic Resource
    Electronic Resource
    A neural network for processing olfactory-like stimuli (1991)
    Springer
    Bulletin of mathematical biology 53 (1991), S. 805-823 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Several critical issues associated with the processing of olfactory stimuli in animals (but focusing on insects) are discussed with a view to designing a neural network which can process olfactory stimuli. This leads to the construction of a neural network that can learn and identify the quality (direction cosines) of an input vector or extract information from a sequence of correlated input vectors, where the latter corresponds to sampling a time varying olfactory stimulus (or other generically similar pattern recognition problems). The network is constructed around a discrete time content-addressable memory (CAM) module which basically satisfies the Hopfield equations with the addition of a unit time delay feedback. This modification improves the convergence properties of the network and is used to control a switch which activates the learning or template formation process when the input is “unknown”. The network dynamics are embedded within a sniff cycle which includes a larger time delay (i.e. an integert s 〈1) that is also used to control the template formation switch. In addition, this time delay is used to modify the input into the CAM module so that the more dominant of two mingling odors or an odor increasing against a background of odors is more readily identified. The performance of the network is evaluated using Monte Carlo simulations and numerical results are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02461485
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  • 2
    Electronic Resource
    Electronic Resource
    Sex ratio genetics and the competitiveness of parasitic wasps (1992)
    Springer
    Bulletin of mathematical biology 54 (1992), S. 295-311 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In the first part of the paper we analyse dynamics of the genetic mechanisms responsible for maintaining biased sex ratios in host-parasitoid interactions. We begin by reviewing recent results relating to the maintenance of sibmating in haplo-diploid populations. We then investigate the evolutionary stable sex ratio in populations in which all or some of the females mate with their brothers. In particular, we derive a diallelic one-locus model for studying evolutionary stable sex ratios in partially sibmating haplo-diploid populations. In the second part of the paper we review the impact of sex ratio on host-parasitoid populations. We then analyse how the sex ratio strategy of one parasitoid species may affect its interaction with another parasitoid species competing for the same host. In particular we show that, although a female biased sex ratio may enhance the inherent competitiveness of one species, it may also destabilize the ecological interaction of the three species so that all become extinct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02464835
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of seed size on seedling size in Virola surinamensis; a within and between tree analysis (1982)
    Springer
    Oecologia 53 (1982), S. 347-351 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We conducted a greenhouse study of the effects of initial seed mass on seedling characteristics in a Panamanian population of Virola surinamensis, a canopy tree in which mean seed mass of different individuals ranges from 1.34 to 4.04g. The system is of particular interest because birds preferentially eat fruits of small-seeded plants, leaving seedlings of large-seeded individuals under conditions of potentially severe sibling competition (Howe and Vande Kerckhove 1980). Effects of differences of mean seed mass between trees are explored using an analysis of variance, while effects of seed-mass variation within crops are demonstrated with a regression analysis. A two-way analysis of variance decisively shows effects of parental source and light condition on seedling height, leaf length, and dry shoot mass (all P〈0.0001). A posteriori tests show that differences in seedling characteristics reflect differences in initial seed mass, with especially strong differences apparent in shoot mass. Regression of seedling characteristics on initial seed mass shows that variation of seed size within a crop is sufficient to influence shoot mass at 15 weeks (P〈0.0001). Effects of size differences of seeds that land adjacent to each other, either under the parent or in monkey droppings, are documented with growth of pairs of seedlings in pots. Differences in shoot height and mass at 15 weeks are evident when seeds of average size differ by only 0.2 g, and dramatic differences are evident when paired seeds differ by an average of 1.5 g. Seedlings grow more when isolated than when planted with conspecifics. These experimental results offer indirect support for the hypothesis that small-seeded Virola parents secure an advantage in reproduction through differential dispersal, while large-seeded plants produce more competitive seedlings under their own crowns — an advantage most likely to be of importance when frugivores are scarce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389011
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  • 4
    Electronic Resource
    Electronic Resource
    Conditioning honeybees to discriminate between heritable odors from full and half sisters (1986)
    Springer
    Journal of comparative physiology 159 (1986), S. 251-256 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Differential conditioning of the proboscis extension reflex in honeybees is used to assess whether worker honeybees can be trained to discriminate between volatile odors emanating from different kin groups consisting of 2 or 20 workers. These odor source group workers are all reared and maintained under identical environmental conditions. They are the progeny of a queen that has been instrumentally inseminated so that eclosing adult workers can be sorted into colormorph full sister patrilines (workers are half sisters across patrilines). We demonstrate that workers are able to discriminate between the odors from groups of 20 individuals only if the groups represent individuals from different patrilines. However, discrimination occurs between groups of 2 individuals even if groups do not represent different patrilines. A number of environmental control experiments are also conducted. From our results we infer that there is heritable variation in the production of volatile odors by worker honeybees at a level that can be detected by the workers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612307
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  • 5
    Electronic Resource
    Electronic Resource
    Olfactory sensitivity and discrimination of mixtures in the honeybeeApis mellifera (1987)
    Springer
    Journal of comparative physiology 160 (1987), S. 239-245 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The work reported here is motivated by questions relating to the perception of olfactory cues in the discrimination of nestmates and kin in the honeybeeApis mellifera. Two sets of experiments are discussed. The first deals with the perception of individual compounds in mixtures made up from various pairs of volatile (citral, geraniol, linalool, and limonene) and nonvolatile (un- and dodecanoic acids) compounds. The second deals with the ability of worker honeybees to discriminate between mixtures made up from the same two compounds (un- and dodecanoic acids; tri- and pentacosane) combined in different proportions. All experiments employ differential conditioning of the proboscis extension reflex as an assay of the ability of workers to discriminate between two odors. Results show that workers can relate mixtures to their component parts, and that workers can discriminate between mixtures of two very similar compounds as long as the proportions are relatively dissimilar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609729
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  • 6
    Electronic Resource
    Electronic Resource
    Olfactory perception in honeybees: Concatenated and mixed odorant stimuli, concentration, and exposure effects (1991)
    Springer
    Journal of comparative physiology 169 (1991), S. 215-230 
    Details
    ISSN: 1432-1351
    Keywords: Differential conditioning ; Proboscis extension reflex ; Learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Here we present results obtained from 7 different series of experiments, all employing odor conditioning of proboscis extension in worker honeybees and each designed to address a particular question involving olfactory perception. The questions relate to: temporal complexity of odor cues; effects of concentration, suppression, and/or potentiation in mixture perception; acquisition and extinction rates, as well as levels of generalization associated with aliphatic compounds that have the same functional groups or same alkyl radical length; and the effects of continuous exposure to odorants in the first several days of adult life on various learning and discrimination tasks involving olfactory perception. From the data obtained in these experiments we were able to conclude the following: First, worker honeybees have a limited ability to perceive complex temporal odor-quality patterns in olfactory stimuli — they learn to associate the quality of only the last part of the stimulus with a sucrose reward. Second, we confirm that citral is qualitatively different in several perceptual contexts involving odor learning and conditioning and our results help elucidate the nature of these differences as they relate to learning, discrimination, mixture perception, and continuous exposure to particular odorants. Third, we appear to have uncovered some important perceptual differences between functional groups attached to the first as opposed to the second carbon atom of alkyl radicals. Finally, we failed to uncover any significant effects relating to continuous exposure to odorants during the first several days of a worker's adult life, despite evidence that considerable sensory development takes place during this period. Thus ontogenetic changes to the peripheral system due to environmental effects appear to leave basic perceptual systems unaltered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215869
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of genes encoding hydroxypyruvate reductase in cucumber (1991)
    Springer
    Plant molecular biology 17 (1991), S. 941-947 
    Details
    ISSN: 1573-5028
    Keywords: hydroxypyruvate reductase ; light regulation ; peroxisomal enzymes ; photorespiration ; plant gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several clones corresponding to the gene encoding NADH-dependent hydroxypyruvate reductase have been isolated from a cucumber genomic library. Restriction mapping indicates the presence of two HPR genes, hpr-A and hpr-B, in the cucumber genome. Examination of the DNAs of individual plants suggests that hpr-A and hpr-B are most likely alleles at a single locus. The sequence of a 6.7 kb genomic fragment that includes the entire transcribed region, 2.2 kb of 5′ flanking sequence, and about 0.8 kb of 3′ flanking sequence reveals the presence of 12 introns in hpr-A. These introns are AT-rich relative to the exons. The donor sequence at the 5′ end of the sixth intron contains an unusual dinucleotide, GC, rather than the nearly invariant GT. Primer extension analysis maps the transcription initiation site to 61 nucleotides upstream of the translation initiation codon. An AT-rich stretch is centered at position −31 with respect to the transcription initiation site, and a potential CCAAT box is centered at position −138. Several elements that are homologous to regulatory elements of other plant genes have been identified in the flanking regions of hpr-A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037078
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  • 8
    Electronic Resource
    Electronic Resource
    Isolation, characterization and sequence analysis of a full-length cDNA clone encoding NADH-dependent hydroxypyruvate reductase from cucumber (1989)
    Springer
    Plant molecular biology 13 (1989), S. 139-150 
    Details
    ISSN: 1573-5028
    Keywords: cDNA ; gene expression ; hydroxypyruvate reductase ; light regulation ; peroxisomal enzyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length cDNA encoding NADH-dependent hydroxypyruvate reductase (HPR), a photorespiratory enzyme localized in leaf peroxisomes, was isolated from a λgt11 cDNA library made by reverse transcription of poly(A)+ RNA from cucumber cotyledons. In vitro transcription and translation of this clone yielded a major polypeptide which was identical in size, 43 kDA, to the product of in vitro translation of cotyledonary poly(A)+ RNA and subsequent immunoprecipitation with HPR antiserum. Escherichia coli cultures transformed with a plasmid construct containing the cDNA insert were induced to express HPR enzyme activity. RNA blot analysis showed that HPR transcript levels rise significantly in the first eight days of light-grown seedling development. This closely resembles the pattern seen for HPR-specific translatable mRNA. DNA blot analysis indicated that a single HPR gene is likely present per haploid genome. Nucleotide sequence analysis revealed an open reading frame of 1146 bases which encodes a polypeptide with a calculated molecular weight of 41.7 kDa. The derived amino acid sequence from this open reading frame is 26% identical and 50% similar to the amino acid sequence of the E. coli enzyme phosphoglycerate dehydrogenase, which catalyzes a similar reaction and functions in a related pathway. Statistical analyses show that this similarity is significant (z〉10). The derived amino acid sequence for HPR also contains the characteristics of an NAD-binding domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016133
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  • 9
    Electronic Resource
    Electronic Resource
    Kin structure and the swarming behavior of the honey bee Apis mellifera (1982)
    Springer
    Behavioral ecology and sociobiology 10 (1982), S. 265-270 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experimental hives obtained from cordovan queens that were instrumentally inseminated with semen from one cordovan and one Italian drone were set up and allowed to swarm. Cordovan provides a resessive genetic marker system (cuticle color) so that the workers from the cordovan and Italian male lines are distinguishable. Our results show that these patrilineal worker groups segregate non-randomly during colony fission and this segregation cannot be explained by observed age structure. Evidence of innate kin recognition in bees has been previously established. We argue that kin recognition could be responsible for the observed non-random grouping of kin during swarming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302815
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  • 10
    Electronic Resource
    Electronic Resource
    Evolutionarily stable dispersal of a waterstrider in a temporally and spatially heterogeneous environment (1989)
    Springer
    Evolutionary ecology 3 (1989), S. 283-298 
    Details
    ISSN: 1573-8477
    Keywords: Evolutionarily stable strategy ; risk-spreading ; dispersal behavior ; flight muscle histolysis ; waterstrider
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Evolutionary stable dispersal and wing muscle histolysis strategies are studied in the waterstriderGerris thoracicus. These strategies relate to spreading reproductive risk. Overwintering individuals have the choice of dispersing to either a brackish sea bay or a rock pool habitat. The former is reproductively more favorable than the latter during warm dry years and less favorable during cool wet years. After spring migration, individuals may histolyse their flight muscles and lay all their eggs in one pool or they may retain their flight ability and lay fewer eggs in total but spread them in several pools. We use a simple two-habitat model to examine the question of habitat dispersal. Our results indicate that, although the value of the evolutionary stable dispersal depends on the degree of variability in the environment and on the probability of local extinctions in either habitat, the population always disperses to both habitats as a consequence of density dependent growth. We use a more detailed multiple-rockpool habitat model to examine the question of wing muscle histolysis as a response to density dependence. Our results indicate that a wing muscle histolysis response to population density is an evolutionarily stable strategy when compared with the two alternatives of females always histolysing or never histolysing their flight muscles. The application of evolutionarily stable theory to stochastic problems presents a number of difficulties. We discuss these difficulties in the context of computing evolutionarily stable strategies for the problems at hand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02285260
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