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  • Elsevier  (369)
  • Springer  (189)
  • 2000-2004  (304)
  • 1970-1974  (148)
  • 1965-1969  (106)
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  • 1
    Electronic Resource
    Electronic Resource
    Interdemic variation in mixed-species association patterns: common diurnal primates of Kibale National Park, Uganda (2000)
    Springer
    Behavioral ecology and sociobiology 47 (2000), S. 129-139 
    Details
    ISSN: 1432-0762
    Keywords: Key words Polyspecific associations ; Group living ; Ecological constraints model ; Food availability ; Group size ; Social organization ; Cercopithecines ; Colobines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We used interdemic variation in the tendency to form mixed-species groups to examine the costs and benefits of association among the primates of Kibale National Park, Uganda. A year-long survey of six sites revealed that the amount of time that the five common diurnal primates [red colobus (Procolobus tephrosceles), black-and-white colobus (Colobus guereza), redtail monkeys (Cercopithecus ascanius), blue monkeys (Cercopithecus mitis), and grey-cheeked mangabeys (Lophocebus albigena)] spent in mixed-species groups varied dramatically among sites. In many cases, the proportion of time that species associated was positively related to their densities. By using detailed behavioral observations of redtail monkeys and red colobus made over 4 years (2660 h) at four sites, we were able to reject the null hypothesis that associations occur by chance for only one of four sites. However, a correlative approach exploring the costs and benefits of association suggests that ecological variables do influence association patterns. We found that redtail monkeys and red colobus overlapped in diet (19.2% of their foraging effort) and traveled further when in mixed-species groups than when alone. Having demonstrated this, we examined the applicability of the ecological constraints model for predicting the proportion of the time spent in mixed-species groups based on food availability. For this analysis we concentrated on red colobus from the site with 35 months of observation and demonstrated that their tendency to be in mixed- species groups was related to food availability. We used two methods to examine if mixed-species associations function to decrease predation risk. First, chimpanzees are known to prey heavily on red colobus, but rarely kill other primates. The time red colobus spent in mixed-species groups was correlated to chimpanzee density, but it was not for the other monkey species, suggesting that mixed-species groups serve to decrease predation risk. Second, when red colobus groups contain more infants and are presumably at the greatest risk of predation, they form mixed-species groups most often. These results demonstrate that the costs and benefits of mixed-species associations vary dramatically over small spatial and temporal scales. If such variation is generally the case, then studies conducted at different locations or different times could easily highlight the importance of difference selective agents in favoring mixed-species associations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050003
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  • 2
    Electronic Resource
    Electronic Resource
    Constraints on Group Size in Red Colobus and Red-tailed Guenons: Examining the Generality of the Ecological Constraints Model (2000)
    Springer
    International journal of primatology 21 (2000), S. 565-585 
    Details
    ISSN: 1573-8604
    Keywords: colobus ; cercopithecine ; group size ; social organization ; food abundance ; day range ; diet ; group movement ; ecological constraints model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ecological constraints model proposes that an increase in group size will increase intragroup feeding competition and thereby constrain group size. Although this model has received wide acceptance, tests of it are based only on a few studies of species that have similar ecological requirements and social organizations, and there are reasons to question the widespread acceptance of the assumptions underpinning it. Via a 2-year study, we explored determinants of group size in species that feed on markedly different types of foods: the folivorous red colobus (Procolobus pennantii) and the frugivorous/insectivorous red-tailed guenon (Cercopithecus ascanius). We established 4 study sites approximately 15 km apart in Kibale National Park, Uganda, to examine the relationship between average group size and food availability. In both species, we quantified interdemic variation in diet, density of food trees, rate of travel, and group size. Red colobus at all sites relied heavily on leaf resources (75.5%–86.9%), but fruit (6.4%–13.9%) and flowers (2.0%–13.9%) were important in some populations. In general, red-tailed guenons fed on fruit (35.7%–59.7%), insects (14.5%–17.6%), and young leaves (12.2%–32.8%), but the amount of time allocated to these foods varied among sites. Average monthly density of trees bearing food items ranged among sites from 45 to 79 trees/ha for red colobus and from 19.6 to 67.3 trees/ha for red-tailed guenons. For both species, rate of travel was similar among sites, with one exception for red colobus. Average red colobus group size varied among sites from 14 to 40 (28 groups counted). Red-tailed guenon group size varied among sites from 11 to 24 (16 groups counted). As predicted by the ecological constraints model, group size increased with food tree density across sites for both species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005557002854
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  • 3
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    Unknown
    Unfavorable successional pathways and the conservation value of logged tropical forest (2004)
    Springer
    Details
    Publication Date: 2004-10-01
    Print ISSN: 0960-3115
    Electronic ISSN: 1572-9710
    Topics: Biology
    Published by Springer
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  • 4
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    Unknown
    Observations on the biology of fallow deer (Dama dama) in Epping Forest, Essex, England (1969)
    Elsevier
    Details
    Publication Date: 1969-10-01
    Print ISSN: 0006-3207
    Electronic ISSN: 1873-2917
    Topics: Biology
    Published by Elsevier
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  • 5
    Electronic Resource
    Electronic Resource
    Field studies of hearing in teleost fish (1973)
    Springer
    Helgoland marine research 24 (1973), S. 371-390 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary 1. Field measurements of hearing in haddock,Melanogrammus aeglefinus, pollack,Pollachius pollachius and ling,Molva molva, show that they are sensitive to sounds in the frequency range from 30 to 500 Hz, with greatest sensitivity from 100 to 300 Hz. 2. At the most sensitive frequencies the thresholds varied between — 15 to — 25 dB relative to a sound pressure of 1µbar. 3. In all three species, the thresholds at some frequencies were affected by the level of ambient sea noise. A direct correlation between the thresholds and the spectrum level of sea noise was obtained in haddock and pollack. 4. The masking effect of sea noise was confirmed in some experiments on cod,Gadus morbua and haddock, where the background noise level was raised artificially. It was found that the masking of a tone signal was reduced by about 8 dB when the tone and noise were from different directions (85° apart), suggesting that directional discrimination may be well developed in these fish.
    Notes: Kurzfassung Versuche über das Hörvermögen verschiedener mariner Fische — des Schellfischs(Melanogrammus aeglefinus), des Pollacks(Pollachius pollachius), des Kabeljaus(Gadus morhua) und des Lengs(Molva molva) — wurden im Biotop, und zwar in 20 m Tiefe bei Loch Torridon (Schottland) durchgeführt. Die Reaktionen der Fische wurden mit Hilfe einer besonderen Dressurtechnik getestet, wobei dem Tonreiz ein leichter elektrischer Schock folgte; wurde das akustische Signal wahrgenommen, traten Veränderungen im Elektrokardiogramm der Fische auf. Alle 4 Arten wiesen ein ähnliches Hörvermögen auf. Im Niederfrequenzbereich von etwa 60–300 Hz wurde die höchste Empfindlichkeit registriert. Bei höheren Frequenzen stellte sich eine Verminderung der Empfindlichkeit ein; nurMolva molva konnte zuverlässig auf einen Ton von 550 Hz abgerichtet werden. Im Bereich niederer Frequenzen waren alle Fische äußerst empfindlich; es ergaben sich Hinweise, daß die Hörschwellen vom Eigenrauschen des Meeres maskiert wurden. Dies wurde durch Versuche bestätigt, bei denen die Intensität des Eigenrauschens vergrößert wurde, die Mithörschwellen aber in konstantem Abstand zum Störpegel blieben. Ferner wurde festgestellt, daß die Verdeckung reiner Töne wesentlich vermindert wurde, wenn Ton und Störpegel aus verschiedenen Richtungen (im rechten Winkel zueinander) abgestrahlt wurden. Daraus ist zu schließen, daß die Fähigkeit, die Richtung der Schallquellen zu unterscheiden, gut entwickelt sein dürfte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01609527
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of parasitism on a nucleopolyhedrovirus amplified in Spodoptera frugiperda larvae parasitized by Campoletis sonorensis (2000)
    Springer
    Entomologia experimentalis et applicata 97 (2000), S. 257-264 
    Details
    ISSN: 1570-7458
    Keywords: fall armyworm ; baculovirus ; serial passage ; virulence ; genotypic variants ; per capita virus production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We evaluated the consequences of parasitism by the solitary ichneumonid endoparasitoid Campoletis sonorensis(Cameron) towards the replication, genetic composition and virulence of a nucleopolyhedrovirus (Baculoviridae) originating from Spodoptera frugiperda(J. E. Smith) larvae. Parasitism by C. sonorensisand viral infection of third and fourth instar S. frugiperdalarvae resulted in reduced growth compared with nonparasitized control larvae. A positive correlation was observed between virus yield and larval instar at the moment of infection. When larvae were virus-inoculated in the fourth instar, parasitism resulted in a significant reduction in mean per capita virus yield compared to the virus yield from nonparasitized larvae. In an experiment involving 10 serial passages of virus in both parasitized and nonparasitized larvae, restriction endonuclease analysis of viral DNA amplified in nonparasitized larvae revealed the presence of the wild-type virus as well as three additional variants (A, B, and C) diagnosed by the presence of novel submolar PstI fragments of different sizes. In contrast, analysis of viral DNA from parasitized larvae showed the presence of the wild-type virus and two other variants (E and F), each characterized by a different submolar BglII fragment. Southern blot analysis indicated that the submolar fragments of variants E and F contained sequences originating from the viral genome. Bioassay of the different virus variants in S. frugiperdalarvae indicated that their virulence was equal or less than that of the wild-type virus. We conclude that parasitism can affect the quantity of virus produced in dually infected and parasitized larvae, but no adverse effects were detected in terms of the biological activity of the virus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004071811224
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  • 7
    Electronic Resource
    Electronic Resource
    Meal size in nymphs of Locusta migratoria (1972)
    Springer
    Entomologia experimentalis et applicata 15 (1972), S. 399-410 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Nahrungsmenge, die von einer Larve der Wanderheuschrecke, Locusta migratoria L., im fünften Entwicklungsstadium bei einer einzigen Mahlzeit verzehrt wird, wurde ermittelt, indem ihr Darm und Darminhalt sofort nach dem Fressen gewogen wurden. In der Mitte des Entwicklungsstadiums wurden größere Mengen verzehrt, Weibchen fraßen mehr als Männchen, jedoch sind die weiblichen Larven ja auch größer. Die Menge der aufgenommenen Nahrung vergrößerte sich mit der Dauer künstlichen Futterentzuges. Sie erreichte ihren Höhepunkt nach sechs Stunden, nach welcher Zeit der Vorderdarm absolut leer war. Die verzehrten Mengen waren je nach der Art der Nahrung unterschiedlich. Auch stellten die Insekten sich so ein, daß sie von einer bestimmten Nahrung mehr zu sich nahmen, wenn sie daran aufgezogen worden waren. Nach längeren Zeitspannen der Isolierung hatten sie die Tendenz, weniger zu fressen. Temperatur und Feuchtigkeit hatten keinen Einfluß auf die Mengen, die verzehrt wurden, außer bei 40°, bei welcher Temperatur sich das gesamte Verhalten zum Fressen ändert.
    Notes: Abstract Meal size in fifth-instar nymphs of Locusta migratoria L. has been investigated by weighing the gut and its contents immediately after feeding. Larger meals are taken in mid-instar, while females eat more in one meal than males under the same conditions. Bigger meals are also eaten after longer periods of food deprivation, but after deprivation for two hours or less, corresponding with the normal interfeed length, meals are smaller than would be expected from the potential maximum foregut volume. The maximum volume attained varies with the type of food available to the insects and is influenced by previous conditioning. Temperature and humidity do not affect meal size except at 40°, at which temperature the usual pattern of feeding is completely altered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293604
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  • 8
    Electronic Resource
    Electronic Resource
    The yrast spectroscopy of neutron-rich nuclei produced in deep-inelastic processes (2003)
    Springer
    The European physical journal 20 (2003), S. 111-112 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The highly sensitive GASP array at the INFN Legnaro Laboratory was used to study the $\gamma$ -ray de-excitation of neutron-rich nuclei produced in the deep-inelastic processes which occur when 230 MeV 36S ions interact with a target of 176Yb. Yrast decay schemes were identified in over forty target-like fragments and in over twenty projectile-like fragments. Analysis of the data has resulted in extensions to the yrast decay sequences of the target-like species, 176Hf, 166Er, 172Yb, and 152Sm. New transitions have also been observed in a number of projectile-like species including 34P and 41Cl. Experimental results are compared with the results of shell model calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epja/i2002-10334-y
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  • 9
    Electronic Resource
    Electronic Resource
    The regulation of feeding in Locusta migratoria: Internal inhibitory mechanisms (1973)
    Springer
    Entomologia experimentalis et applicata 16 (1973), S. 329-342 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Alle Hauptnerven des Mund- und Rachennervensystems wurden kontrolliert reseziert. Erst wenn die rückwärtigen Rachennerven zerschnitten werden, nehmen die Insekten wesentlich mehr Nahrung zu sich. Solche Insekten versuchen längere Zeit zu fressen. Wenn sich während des Fressens der Vorderdarm füllt, wird keine Nahrung an den Mitteldarm weitergegeben und sein Vorderende ist der letzte Teil, der sich vollständig ausdehnt. Nach Durchtrennung der rückwärtigen Rachennerven sind alle Teile des Vorderdarms offen-sichtlich mehr gedehnt. Eine solche erhöhte Nahrungsaufnahme tritt aber nicht ein, wenn die Nahrung relativ ungünstig ist. Das Abbinden des Kropfes verursacht beim nachträglichen Fressen keine übermäßige Ausdehnung des Vorderteiles. Die Nahrungsaufnahme hat keinen Unterschied im Körpervolumen zur Folge und das Durchtrennen des ventralen Nervenstranges bleibt ohne Einfluß auf die nachträglich aufgenommenen Nahrungsmengen. Das vergrößerte Darmvolumen wird durch Kollaps des Luftsackes kompensiert.
    Notes: Abstract During the course of a meal by insects with an empty gut, food is held in the foregut and the midgut remains empty. The last part of the foregut to fill is the extreme anterior end of the crop, and stretch receptors in this region control the amount eaten. Cutting the posterior pharyngeal nerves isolates these receptors from the frontal garglion and results in hyperphagia pharyngeal nerves isolates these receptors from the frontal garglion and results in hyperphagia during one meal. On unfavourable food, when smaller amounts are eaten, distension of the foregut is not involved in regulating meal size. Feedback from receptors in the body wall is not important in regulating meal size; most of the increase in gut volume resulting from feeding is taken up by the collapse of the air sacs so that there is little or no change in the body volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334244
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  • 10
    Electronic Resource
    Electronic Resource
    The functions of the maxillary palps of Acrididae (Orthoptera) (1970)
    Springer
    Entomologia experimentalis et applicata 13 (1970), S. 363-376 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Funktionen der Maxillartaster von Locusta migratoria migratorioides (R. & F.), Schistocerca gregaria (Forskål) und Chortippus parallelus (Zett.) wurden unter Anwendung verschiedener Verfahren untersucht. Die Tasterbewegungen wurden kinematographisch analysiert und als Schlagen und Tasten klassifiziert; das letztere tritt hauptsächlich kurz vor und nach, aber ebenso gut auch während der Nahrungsaufnahme auf. Die Sensillen an den Tasterenden berühren beim Tasten häufig das Substrat. Vorausgesetzt, daß die Insekten nicht gehungert hatten, wurde Bellis allein nach Betasten abgelehnt; nach längerem Hungern erfolgte jedoch die Ablehnung erst nach Beißen. Weitere Versuche, bei denen Extrakte der Kutikula von Poa oder Bellis verwendet wurden, zeigten, daß Annahme oder Ablehnung von der chemischen Natur des Substrats abhängen, welches von den Tastern berührt wird. Betasten eines geeigneten Substrats führte nicht unmittelbar zum Beißen, ruft aber eine Verhaltensweise hervor, die ihrerseits das Beißen fördert. Daraus wird geschlossen, daß die von den Tastern wahrgenommenen chemischen Reize für die Nahrungswahl der Acrididen wichtig sind, wenn die Insekten normal fressen. Nach Hunger ruft mechanische Reizung der Taster oder anderer Mundteile Beißen auch beim Fehlen geeigneter chemischer Reize hervor. Die häufigen kurzen Kontakte der Palpen mit dem Substrat während des Tastens erlauben offenbar den Sensillen, einen beständigen Strom von Informationen an das Zentralnervensystem zu liefern, ohne selbst angepaßt (ermüdet) zu werden.
    Notes: Abstract The functions of the maxillary palps of acridids have been investigated in experiments with Locusta migratoria migratorioides (R. & F.), Schistocerca gregaria (Forsk.) and Chorthippus parallelus (Zett.). The palp makes small irregular flicking movements and more extensive rapid vibrations described as palpation. Both activities involve the same basic movements of the palp segments. Palpation is essentially related to feeding and in normally feeding insects the palps play an important role in food selection, but as starvation is prolonged they become unimportant. Selection depends on appropriate chemical stimulation from the cuticle on the surface of the leaf. Palpation on this leads to head lowering and to biting if appropriate tactile stimuli are then received. The control of biting is discussed. The frequent but very brief, contacts of the sensilla on the tips of the palps with the substratum during palpation may enable them to relay information to the central nervous system more or less continuously without adapting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333491
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