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  • Articles: DFG German National Licenses  (24)
  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The individual positions of 200 intertidal chitons [Acanthopleura brevispinosa (Sowerby) and A. gemmata (Blainville)] were recorded throughout 55 low tides on a Somalian shore, using a discrete sampling method. Both species feed during nocturnal low tide and rest during the day and high tide. Due to this activity rhythm, individual positions recorded during diurnal and nocturnal low tides give information on the rest habits of the chitons and on their movements, respectively. The resting and feeding fixes were analyzed with two new complementary methods. Both species show a distinct homing behaviour with periodical shift to new homes more frequent in A. brevispinosa than in A. gemmata. The latter species shows a stronger constancy to its feeding ground. The two species differ most in the orientation and length of their excursions. Due to their different movement pattern the two species minimize zonal overlapping during the night, which in turn reduces the interspecific competition for food.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 24 (1986), S. 437-449 
    ISSN: 1432-1416
    Keywords: Comb building ; Self-organization ; Gain-sheet fast Fourier procedure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We developed a mathematical model and an algorithm for numerical treatment of a model of honeycomb construction in a beehive. The model contains essential features of the bee-bee and bee-wax interactions, and in a qualitative way captures the dynamics of parallel comb construction. The construction is represented by a set of dynamical coupled partial differential equations for the density of bees situated on the hive ceiling, and the quantity of wax distributed by the bees. A spectral algorithm is invented for treatment of these equations, based on a modified thin-sheet gain scheme and a fast Fourier transform technique.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1939
    Keywords: Foraging benefit ; Capture rate ; Competition tate ; Food flow ; Foraging area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A model of individual foraging in social insects as presented that formalises the dynamics of foraging and concentrates on the collective rather than the individual benefit, quantifying the relationships between a colony's foraging area, number of foragers and foraging energy budget and the food sources' rate of arrival, disappearance and capture. A series of experiments, in which a number of prey were offered to colonies of the individually foraging antPachycondyla (ex-Neoponera) apicalis confirm the hypotheses implicit in the model and measured the rates of capture and competition. 60 days observation of 3P. apicalis colonies' foraging activity are summarised and used in conjunction with the model to obtain estimations of the density and rate of arrival of available prey in the foraging area. We examine how a colony's foraging benefit may be influenced by its foraging area, the number of foragers, and the forager/non-forager ratio and show that a colony's jocial structure strongly limits its potential foraging benefit. Within these limits,P. apicalis does not appear to be an optimal forager.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1420-9098
    Keywords: Orientation ; individual memory ; chemical communication ; Formicidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relative contribution of visual and chemical components in the orientation ofLasius niger andIridomyrmex humilis (Argentine ant) workers during mass recruitment to newly discovered food sources is analyzed over short time intervals. While both species orient in response to the trail pheromone, a large number ofL. niger foragers rapidly switch to a more individual orientation, based on their memory of environmental cues.I. humilis workers, on the other hand, predominantly use collective chemical cues. The effect of the number of reinforcements on visual learning and its interference with chemical communication show that olfactory cues always prevail in the Argentine ant. InL. niger, the proportion of ants orienting to visual cues is independent of the trail concentration. Detailed observations of the trail-laying behavior of individually marked foragers show that nearly all theI. humilis workers initially lay a trail, whereas only half theL. niger foragers do so. This proportion decreases considerably with the number of trips performed byL. niger workers, while remaining constant for the Argentine ants. These results are interpreted with respect to the species' behavioral ecology.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les ouvrières deLeptothorax unifasciatus utilisent des repères chimiques et des repères visuels au cours des activités de fourragement. Cependant, une orientation ménotactique (ampoule lumineuse de 60 watt) et reposant sur des repères visuels ambiants domient une orientation chimique. Un trajet effectué vers la nourriture suffit aux ouvrières pour s'orienter ensuite sur une ampoule lumineuse. Les ouvrières tracent une piste au cours du fourragement n'ayant pas fonction de recrutement, mais agissant comme repère orientationnel individuel. Ces pistes sont distinguées et préférées même lorsqu'elles sont superposées à plusieurs autres. Néanmoins, les ouvrières acceptent de suivre les pistes de leurs congénères en l'absence de leur propre piste. Les ouvrières nouvellement recrutées sont incapables de s'orienter sur les pistes chimiques.
    Notes: Summary Leptothorax unifasciatus workers use both chemical and visual cues when foraging. A visual orientation based on menotactical cues (60 watt light-bulb) and environmental cues (laboratory surroundings) dominate over a chemical orientation. The learning response to a 60 watt light-bulb cue occurs after a single trip to the food source. Workers lay down a trail when foraging which helps them to orient themselves but does not recruit other nestmates. Such trails are distinguished and preferred even when superposed by several other nestmates' trails. Nevertheless, the foragers are able to follow their nestmates' trails if their own is somehow missing. Newly recruited ants are unable to orient along chemical trails.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 39 (1992), S. 59-72 
    ISSN: 1420-9098
    Keywords: Hymenoptera ; Formicidae ; Lasius niger ; food recruitment ; trail laying behaviour ; collective decision making
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The trail-laying behaviour of foragers of the antLasius niger was observed in the laboratory on a 20 cm bridge between the nest and the food source. We measured both the frequency of trail laying, as defined by the proportion of trips during which trail laying occurred, and its intensity, as defined by the number of marks laid during one bridge crossing. Foragers do not exhibit trail-laying behaviour until a food source is discovered. Trail laying then occurs more or less equally both to and from the nest, and both its frequency and intensity decrease as the recruitment proceeds. Foragers from very small colonies less than a year old appear to have quantitatively the same trail laying behaviour as those from older and much larger colonies. Groups of recruiters and recruits were individually marked. Their trail laying intensity was similar, both for trips to and from the nest, and for an ant's first, second, third and fourth trip. The frequency diminished rapidly with the number of trips made by each individual, and was 2–3 times higher for recruiters than for recruits, for trips both to and from the nest. Even though foragers stop marking after a variable number of passages, they continue to move between the nest and the food source, and other ants start marking. Different foragers appear to have widely different levels of trail laying, although we cannot say whether these differences are stable between different recruitments. Trail laying is strongly affected by the foragers' position on the bridge, especially for ants returning to the nest which lay up to five times more on the segment closest to the source than that closest to the nest. Foragers on a weakly marked trail appear to mark more than those on a well-marked trail. However, this effect is weak and could partly be attributed to their lower speed. Finally, a model using the experimental data gathered on the individuals' trail-laying behaviour reproduced satisfactorily the colony's overall trail laying.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 45 (1998), S. 191-195 
    ISSN: 1420-9098
    Keywords: Key words: Group effect, latency time, fungus-growing termites, building behavior, bees, aggressiveness.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: We suggest that group effect need not be invoked to explain the differences in latency times exhibited by groups of different sizes in the initiation of building in the termite Macrotermes subhyalinus (Rambur). A simple, alternative, model is presented, that is fully consistent with experimental data.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les ouvrières deLeptothorax unifasciatus différencient de nouvelles aires de celles précédemment explorées. En effet, un comportement de «va-et-vient» apparaît plus fréquent sur un papier vierge que sur un papier familier à la colonie. La chute d'activité sur un papier vierge après quelques heures indique que ce dernier devient rapidement familier à la colonie dans le dispositif expérimental utilisé. Les expériences suggèrent que le territoire est modifié chimiquement par l'activité des fourmis, mais la possibilité d'un marquage chimique n'a toutefois pas été explorée. Trois facteurs contrôlent le niveau d'activité de fourragement chezL. unifasciatus: 1o la nature de l'aire de récolte (connue ou inconnue); 2o la taille de la société; 3o le temps de séjour de la société dans un même nid. Des sociétés établies récemment dans leur nid montrent un niveau d'activité de fourragement plus élevé sur une aire de récolte inconnue que sur une aire familière. Dans tous les cas, il existe une relation linéaire liant la taille de la société et son activité. Des sociétés établies depuis longtemps dans un même nid montrent toujours une activité inférieure aux sociétés récemment établies. Aucune différence n'est observée entre une aire de récolte inconnue et familière. De plus, la taille de la société apparaît être moins influente sur son activité générale que pour une société récemment établie dans son nid. Ces résultats sont interprétés en termes éco-éthologiques, tenant compte d'une caractéristique biologique essentielle des sociétés deL. unifasciatus: les déménagements fréquents, saisonniers ou liés à la précarité des nids.
    Notes: Summary Leptothorax unifasciatus workers differentiate new areas from those previously explored. Indeed, a “coming and going” behaviour appears more frequent on a virgin paper than on a familiar one. The decrease of activity on a new paper after some hours indicates that this species rapidly gets to known such an area in the experimental device used here. The experiments suggest that the area is chemically modified by the ants' activity, but the possibility of a specific marking behaviour was not further investigated. Three factors control the level of foraging activity inL. unifasciatus: 1o. The nature of the foraging area (familiar or virgin). 2o. The size of the society. 3o. The age of the nest-site. Societies newly established in their nest show a higher level of foraging activity on a virgin area than on a familiar one. In every case, there is a linear relation between the size of the society and its activity. Long-settled societies always show a lower activity than recently established ones, and no difference was observed when they recruited on a virgin and a familiar area. Moreover, the society size appears to be less important in determining the general level of activity than for recently-settled societies. These results are tentatively interpreted in eco-ethological terms, taking into account a main biological characteristic ofLeptothorax societies: frequent nest emigrations that are either seasonal or due to fragile nest-sites.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 30 (1983), S. 347-360 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Une étude du recrutement global, menée chezTetramorium impurum, a mis en évidence ses principales caractéristiques. La croissance de la population participant au recrutement est de typè logistique. De plus, des oscillations amorties sont observées. Celles-ci ont deux origines: les délais temporels dans les recrutements et l'effet de l'encombrement à la source. Un modèle mathématique permettant de reproduire ces différents effets et de quantifier les paramètres pertinents est présenté.
    Notes: Summary A study of global recruitment inTetramorium impurum has shown its main characteristics. The growth of population in the neighbourhood of the food source is a logistic curve. Damped oscillations are observed. These oscillations are the result of time delay in recruitment and crowding around the food source. A mathematical model is able to reproduce these different effects and it allows one to identify and give quantitative values to pertinent parameters.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 36 (1989), S. 339-347 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume On présente un modèle simple de choix du secteur de fourragement par des fourmis. Ce choix se fait en fonction de la quantité de phéromone associée à chaque secteur, et est autocatalytique puisque les fourrageuses qui trouvent de la nourriture dans un secteur y ajoutent de la phéromone. Quand la nourriture d'un secteur est épuisée, les fourrageuses transfèrent spontanément leur activité vers le secteur adjacent. Si la richesse en nourriture augmente, le modèle passe d'un fourragement aléatoire à la formation d'une piste qui tourne autour du nid. Plus la richesse est élevée, plus la piste tourne lentement, jusqu'à devenir figée en un secteur. Ces résultats correspondent aux observations faites sur la fourmiMessor pergandei parBernstein (1975),Rissing etWheeler (1976). reconcilient une apparente contradiction entre eux.
    Notes: Summary A simple model is described wherein ant foragers choose a foraging sector as a function of the pheromone concentration associated with each sector. The choice is autocatalytic, as foragers that find food in a sector add to its pheromone. As a sector's food runs out, the foragers spontaneously switch to the adjacent sector. With increasing food abundance, the model passes from random foraging to the formation of a trail that rotates about the nest. The greater the abundance the more slowly the trail rotates until it finally becomes fixed on one sector. These results agree with experimental observations made on the harvester antMessor pergandei byBernstein (1975) andRissing andWheeler (1976), and reconcile an apparent contradiction between them.
    Type of Medium: Electronic Resource
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