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  • evolution  (64)
  • oxidation  (64)
  • Springer  (128)
  • 2000-2004  (128)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of ornithology 141 (2000), S. 263-274 
    ISSN: 1439-0361
    Keywords: Systematics ; evolution ; anagenesis ; genealogy ; reference system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Verglichen mit anderen Tiergruppen, scheint die artliche Bestandsaufnahme der rezenten Vögel nahezu abgeschlossen zu sein. Doch ist das System der Vögel weiterhin umstritten und mit vielen Neuerungen konfrontiert. Die Gründe dafür liegen hauptsächlich in neuen, vor allem molekularbiologischen Methoden und in den unerwartet reichen Fossilfunden der jüngsten Zeit. Als Beispiele werden Altgaumenvögel, Kranichvögel, Ibisse, Flamingos, Mausvögel, Hopfe und Sperlingsvögel kurz behandelt. Die hier erzielten Fortschritte lassen die Befürchtung Stresemanns, die Großsystematik der Vögel sei mit den vorhandenen Methoden phylogenetisch nicht interpretierbar, zunächst als unbergründet erscheinen. Doch erwachsen einer solchen Interpretation andere Hindernisse, deren Bedeutung bisher zu wenig beachtet wurde, nämlich Parallelentwicklungen, die viel verbreiteter sind als gemeinhin angenommen. Ihre Häufigkeit lässt sich sogar mit evolutionsbiologischen Argumenten begründen. Es ist deshalb nicht zu erwarten, dass die Diskussionen um das „richtige“ System bald verstummen. Um dennoch die Eindeutigkeit der Information in nicht-systematischen Veröffentlichungen zu wahren, wird empfohlen ein etabliertes Referenzsystem auf Zeit zu wählen.
    Notes: Summary Unlike in most animal classes the inventory of extant species of the class Aves seems to be almost complete. Nevertheless avian systematics is challenged by many novelties and seems far from being settled. This is caused mainly by the application of novel methods of molecular analysis to phylogenetic problems and by the unexpectedly rich fossil record collected within the last 10–20 years. Examples from the Palaeognathae, Gruiformes, Threskiornithidae, Phoenicopteridae, Coliiformes, Upupiformes and Passeriformes are briefly treated. The progress in the field seems to disprove Stresemann's pessimistic view that the phylogeny of higher categories (orders) cannot be reconstructed by the available methods. However, phylogenetic interpretations are impeded by obstacles not considered by Stresemann and highly underestimated in most cases, namely by multiple independent developments leading to identical features. Frequent parallel developments are to be expected for theoretical evolutionary reasons. The diagnosis of such homoplasies can be extremely difficult or even impossible. Therefore we cannot expect the discussion about the “best” system of birds to end in the near future. Considering this dynamic situation in systematics, it is recommended to maintain unambiguousness of information in not strictly systematic publications by refering to a well established system as a temporally limited reference.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta biotheoretica 48 (2000), S. 137-147 
    ISSN: 1572-8358
    Keywords: Sex ; sexual selection ; mate selection ; evolution ; ploidy ; assortative mating ; recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using computer simulations I studied the simultaneous effect of variable environments, mutation rates, ploidy, number of loci subject to evolution and random and assortative mating on various reproductive systems. The simulations showed that mutants for sex and recombination are evolutionarily stable, displacing alleles for monosexuality in diploid populations mating assortatively under variable selection pressure. Assortative mating reduced excessive allelic variance induced by recombination and sex, especially among diploids. Results suggest a novel adaptive value for sex and recombination. They show that the adaptive value of diploidy and that of the segregation of sexes is different to that of sex and recombination. The results suggest that the emergence of sex had to be preceded by the emergence of diploid monosexual organisms and provide an explanation for the emergence and maintenance of sex among diploids and for the scarcity of sex among haploid organisms.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 97 (2000), S. 237-249 
    ISSN: 1570-7458
    Keywords: herbivores ; predators ; parasitoids ; mutualism ; induced defence ; behaviour ; ecology ; evolution ; sensory physiology ; plant fitness ; pathogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Herbivorous and carnivorous arthropods use plant volatiles when foraging for food. In response to herbivory, plants emit a blend that may be quantitatively and qualitatively different from the blend emitted when intact. This induced volatile blend alters the interactions of the plant with its environment. We review recent developments regarding the induction mechanism as well as the ecological consequences in a multitrophic and evolutionary context. It has been well established that carnivores (predators and parasitoids) are attracted by the volatiles induced by their herbivorous victims. This concerns an active plant response. In the case of attraction of predators, this is likely to result in a fitness benefit to the plant, because through consumption a predator removes the herbivores from the plant. However, the benefit to the plant is less clear when parasitoids are attracted, because parasitisation does usually not result in an instantaneous or in a complete termination of consumption by the herbivore. Recently, empirical evidence has been obtained that shows that the plant's response can increase plant fitness, in terms of seed production, due to a reduced consumption rate of parasitized herbivores. However, apart from a benefit from attracting carnivores, the induced volatiles can have a serious cost because there is an increasing number of studies that show that herbivores can be attracted. However, this does not necessarily result in settlement of the herbivores on the emitting plant. The presence of cues from herbivores and/or carnivores that indicate that the plant is a competitor- and/or enemy-dense space, may lead to an avoidance response. Thus, the benefit of emission of induced volatiles is likely to depend on the prevailing faunal composition. Whether plants can adjust their response and influence the emission of the induced volatiles, taking the prevalent environmental conditions into account, is an interesting question that needs to be addressed. The induced volatiles may also affect interactions of the emitting plant with its neighbours, e.g., through altered competitive ability or by the neighbour exploiting the emitted information. Major questions to be addressed in this research field comprise mechanistic aspects, such as the identification of the minimally effective blend of volatiles that explains the attraction of carnivores to herbivore-infested plants, and evolutionary aspects such as the fitness consequences of induced volatiles. The elucidation of mechanistic aspects is important for addressing ecological and evolutionary questions. For instance, an important tool to address ecological and evolutionary aspects would be to have plant pairs that differ in only a single trait. Such plants are likely to become available in the near future as a result of mechanistic studies on signal-transduction pathways and an increased interest in molecular genetics.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 95 (2000), S. 141-149 
    ISSN: 1570-7458
    Keywords: ecology ; reproductive success ; fecundity ; intraspecific competition ; evolution ; pest outbreaks ; pest control ; chemical control ; economic threshold ; oilseed rape ; turnip rape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the rapeseed pollen beetle Meligethes aeneus F. (Col., Nitidulidae) from areas with 0–16 years of history of intensive rapeseed growing were compared for key ecological characters. During the first 16 years of rapeseed cultivation the reproductive success of M. aeneus increased 200–300% over that of the beetles living on the natural host plants, cruciferous weeds. The increase was linear over time and statistically highly significant, and it did not appear to be related to food quality or to the size of the beetles. During the same period the tolerance to intraspecific competition decreased, possibly due to the relative absence of such competition on the new crop. Furthermore, the optimum population density for M. aeneus to maximize the size of its next generation on summer turnip rape was determined to be 0.5–1.0 beetles/plant, which is slightly below the economic threshold for chemical control (1 beetle/plant). Therefore the practical protection of the rapeseed yield also ensures the highest possible pest population size for the next year. These mechanisms may in part explain the particular noxiousness of the species as a pest all over Europe. In general these data show that after the introduction of a new crop plant into a region, significant changes during the recruitment process in a pestiferous insect may take place, contributing to the future pest status of the insect. It is suggested that such genetic and ecological changes in insects may be a more common mechanism than previously thought in initiating and sustaining pest outbreaks, and that conventional pest management methods may enhance that effect.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of insect behavior 13 (2000), S. 71-86 
    ISSN: 1572-8889
    Keywords: copulatory courtship ; behavioral interactions ; songs ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract D. birchii and D. serrata, two endemic Australian Drosophila species, have a copulatory courtship. The males of these species begin to court the female after mounting her and often go on with the courtship after the copulation is over. In the present paper we have described behavioral interactions between the male and the female and analyzed acoustic signals produced by the flies during courtship. Species differences were more pronounced in female than in male behavior. Variation within the species was obvious in the relative proportions of time the flies spent in different behaviors. Even though courtship took place nearly solely during copulation, some remains of precopulatory courtship were observed in both species. It is suggested that copulatory courtship exhibited by D. birchii and D. serrata flies is a derived rather than a primitive character.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 30 (2000), S. 727-731 
    ISSN: 1572-8838
    Keywords: electrosynthesis ; oxidation ; lignin ; vanillin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrochemical oxidative degradation of Kraft lignin was investigated in batch and flow cells on Pt, Au, Ni, Cu, DSA–O2 and PbO2 anodes. Production of vanillin was evaluated by means of formal kinetic analyses. Conversion and chemical yields were found to be dependent mainly on the applied current density, that is on the partial pressure of oxygen at the interface, while the nature of the electrode influenced the reaction rates.
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  • 7
    ISSN: 1572-879X
    Keywords: oxidation ; reduction of palladium catalysts ; chlorine effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pd–chloride precursor salt was used to prepare Pd/Al2O3 catalysts. TPSR measurements showed three distinct reactions for the oxidation of propane on palladium surface under excess of hydrocarbon: complete oxidation, steam reforming and propane hydrogenolysis. Propane oxidation on palladium catalysts was related to the Pd2+ sites observed on Pd/Al2O3 through infrared of adsorbed carbon monoxide. In fresh catalysts reduced by H2, the IR spectra showed the linear and bridge adsorbed CO species on the Pd0 surface. After propane reaction, a new band at 2130 cm-1 related to CO adsorption on Pd2+ species was noted. Carbon monoxide species adsorbed on Pd0 were also observed in all samples after reaction. Our results suggest surface ratios of Pd0/PdO during the propane oxidation. On the other hand, time on stream conversions of the complete oxidation of propane were affected by either the water generated during the reaction or added as a reactant at 10 vol%. The water generated by the reaction helped to eliminate chlorine residues in the form of oxychloride species leading to an increasing of the activity. However, the presence of water into the reaction mixture caused a strong decreasing of the activity. The inhibition mechanism of propane oxidation in the presence of water consisted in the dissociative adsorption of water on palladium sites with the possible formation of palladium hydroxide (Pd–OH) at the surface, diminishing the number of active surface sites. Dynamic fluctuations into the reaction conditions supported the idea that a pseudo‐equilibrium adsorption–desorption of water was reached. After water removal or increasing in the reaction temperature the equilibrium was shifted to the direction of OH–Pd decomposition. This behavior suggests that the inhibitory effect of water is a reversible phenomenon, being a function of the amount of water and the reaction temperature.
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  • 8
    ISSN: 1572-879X
    Keywords: methane ; oxidation ; aliphatic hydrocarbons ; zeolite ; recycle reactor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Conversion of methane in high yields to C4+ nonaromatic hydrocarbons was demonstrated in a recycle system. The principal components of the recycle system included an oxidative coupling reactor with a Mn/Na2WO4/SiO2 catalyst at 800°C for conversion of methane to ethylene, and a reactor with an H-ZSM-5 zeolite at 275°C for subsequent conversion of ethylene to higher hydrocarbons. Total yields of C4+ products were in the range of 60–80%, and yields of C4+ nonaromatic hydrocarbons were in the range of 50–60%.
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  • 9
    ISSN: 1572-9028
    Keywords: oxidation ; oxyacetoxylation ; alloy ; palladium ; bismuth ; benzylacetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Benzylacetate synthesis from toluene, acetic acid and oxygen on Pd–Bi binary catalyst was studied in the liquid phase. By incorporation of Bi with Pd, both the activity and selectivity were improved. Especially better stability was obtained with the catalyst having Pd/Bi = 3. Deactivation of the catalyst was investigated in detail by XRD, XPS, TEM, elemental analysis, EPMA and so on. Comparing the used catalyst with the fresh one, it was indicated that the main cause of deactivation was the dissolution of Pd into the reaction mixture from the most outer surface of the catalyst. By adopting proper reaction conditions to prevent the Pd dissolution, the catalyst having Pd/Bi = 3 was suggested to be used as an industrial catalyst.
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  • 10
    ISSN: 1572-9028
    Keywords: nitric oxide ; ammonia ; oxidation ; X-ray photoelectron spectroscopy ; scanning tunnelling microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The dissociative chemisorption of nitric oxide at Cu(110) has been shown to result in rapid ordering of oxygen adatoms as (2×1)O chains oriented along the 〈100〉 direction while the associated nitrogen adatoms are mainly disordered at 295 K. Surface diffusion of the N adatoms, following bond cleavage, is activated and ordering of the (2×3)N strings occurs on heating to 430 K. A number of distinct reaction pathways have been isolated during the oxidation of ammonia resulting in the formation of either chemisorbed imide or nitrogen adatoms. The latter depending on temperature, may exhibit a (2×3)N, a (3×3)N or both structures may exist simultaneously. The concentration of nitrogen in the complete (2×3)N structure has been determined to be 6.6×1014 cm-2, with only a 25% decrease in nitrogen concentration leading to the transformation to the (3×3)N structure. The oxygen atoms at a Cu(110)–O overlayer, and present at the ends of the (2×1) strings terminating in steps, show specific reactivity when exposed to ammonia at 375 K resulting in the “decoration” of the steps with imide species while the oxygens within the (2×1) strings remain unreactive.
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