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  • 1
    Electronic Resource
    Electronic Resource
    Working the patch (1987)
    [s.l.] : Nature Publishing Group
    Nature 328 (1987), S. 303-303 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] OPTIMALITY modelling in evolutionary biology has not had an altogether smooth ride. This has had little to do with the actual merits or otherwise of optimization models, but a lot to do with the perception of what they set out to achieve. Interpreted naively (or perversely) the notion of optimality ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/328303a0
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  • 2
    Electronic Resource
    Electronic Resource
    Flower choice by honey bees (Apis mellifera L.): sex-phase of flowers and preferences among nectar and pollen foragers (1995)
    Springer
    Oecologia 101 (1995), S. 258-264 
    Details
    ISSN: 1432-1939
    Keywords: Apis mellifera ; Lavandula stoechas ; Pollen content ; Nectar content ; Foraging preference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bees foraging for nectar should choose different inflorescences from those foraging for both pollen and nectar, if inflorescences consist of differing proportions of male and female flowers, particularly if the sex phases of the flowers differ in nectar content as well as the occurrence of pollen. This study tested this prediction using worker honey bees (Apis mellifera L.) foraging on inflorescences of Lavandula stoechas. Female flowers contained about twice the volume of nectar of male flowers. As one would predict, bees foraging for nectar only chose inflorescences with disproportionately more female flowers: time spent on the inflorescence was correlated with the number of female flowers, but not with the number of male flowers. Inflorescence size was inversely correlated with the number of female flowers, and could be used as a morphological cue by these bees. Also as predicted, workers foraging for both pollen and nectar chose inflorescences with relatively greater numbers of both male and female flowers: time spent on these inflorescences was correlated with the number of male flowers, but not with the number of females flowers. A morphological cue inversely associated with such inflorescences is the size of the bract display. Choice of flowers within inflorescences was also influenced predictably, but preferences appeared to be based upon corolla size rather than directly on sex phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317292
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  • 3
    Electronic Resource
    Electronic Resource
    Male crickets increase sperm number in relation to competition and female size (1996)
    Springer
    Behavioral ecology and sociobiology 38 (1996), S. 349-353 
    Details
    ISSN: 1432-0762
    Keywords: Key words Sperm competition ; Crickets ; Acheta domesticus ; Gryllodes supplicans ; Intermale competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There is evidence to suggest that males of various species can respond to the threat of sperm competition by varying the amount of sperm transferred during copulation. We tested this in two species of cricket, Acheta domesticus and Gryllodes supplicans (Orthoptera: Gryllidae) by varying the apparent threat of intermale competition experimentally. The results showed that males of both species increased the amount of sperm transferred as apparent competition increased and that male A. domesticus transferred more sperm when encountering larger females. The results also showed that male G. supplicans produced a larger spermatophylax when a larger ampulla was transferred, a relationship consistent with a sperm protection function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050251
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  • 4
    Electronic Resource
    Electronic Resource
    Competition affects risk-sensitivity in foraging shrews (1985)
    Springer
    Behavioral ecology and sociobiology 16 (1985), S. 379-382 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Studies of risk-sensitive foraging have so far focused only on the effect of food demand on choice of feeding site. We suggest that competition is likely to be another factor influencing risksensitivity. A choice experiment with common shrews showed that, in the absence of competition, risk-aversion increased with increasing food intake relative to requirement. When apparent competitors were present, however, shrews were risk-indifferent regardless of their estimated requirement. The switch to risk-indifference in the presence of competitors appears to be an all-or-nothing rule of thumb which is not modified by experience with reward probability distributions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295552
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  • 5
    Electronic Resource
    Electronic Resource
    Kinship and social tolerance among female and juvenile wild house mice: kin bias but not kin discrimination (1995)
    Springer
    Behavioral ecology and sociobiology 36 (1995), S. 333-342 
    Details
    ISSN: 1432-0762
    Keywords: Mus domesticus ; Kin bias ; Aggression Group territoriality ; Territory invasion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Kin-biased social tolerance among house mice has been interpreted in terms of kin discrimination. However, several lines of evidence suggest it may instead be an incidental artifact of group member discrimination. This leads to very different predictions about the social consequences of relatedness within and between social groups. Social interactions between wild-stock adult female and juvenile house mice (Mus domesticus) established in neighbouring territorial groups within enclosures reveal relatedness to dominant males within groups as the major factor determining social tolerance of juveniles by females. Relatedness to the female herself had no significant independent effect on responses indicating tolerance. Females were generally more aggressive toward neighbouring-group juveniles (all unrelated to females) compared with those from their own group (all related to females), but were most aggressive toward neighbouring juveniles sired by the neighbouring dominant male. They were also more aggressive toward their own-group juveniles that had been sired by the neighbouring dominant but only when encountered in the neighbouring territory and with a greater bias against female juveniles. Females were least aggressive toward own-group juveniles sired by their own-group dominant male. The sire-bias in tolerance among females is similar to that reported among the dominant males themselves in an earlier study. As a result of the combined sire-bias in tolerance by adult males and females, juveniles sired by their own-group dominant males become less likely to intrude into a neighbouring territory with time. Overall, the results suggest that differences in social tolerance reflect discrimination on the basis of social group membership rather than relatedness between interactants and thus provide strong experimental evidence in support of incidental kin bias rather than kin discrimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167794
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  • 6
    Electronic Resource
    Electronic Resource
    Kinship and social tolerance among female and juvenile wild house mice: kin bias but not kin discrimination (1995)
    Springer
    Behavioral ecology and sociobiology 36 (1995), S. 333-342 
    Details
    ISSN: 1432-0762
    Keywords: Key wordsMus domesticus ; Kin bias ; Aggression ; Group territoriality ; Territory invasion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Kin-biased social tolerance among house mice has been interpreted in terms of kin discrimination. However, several lines of evidence suggest it may instead be an incidental artifact of group member discrimination. This leads to very different predictions about the social consequences of relatedness within and between social groups. Social interactions between wild-stock adult female and juvenile house mice (Mus domesticus) established in neighbouring territorial groups within enclosures reveal relatedness to dominant males within groups as the major factor determining social tolerance of juveniles by females. Relatedness to the female herself had no significant independent effect on responses indicating tolerance. Females were generally more aggressive toward neighbouring-group juveniles (all unrelated to females) compared with those from their own group (all related to females), but were most aggressive toward neighbouring juveniles sired by the neighbouring dominant male. They were also more aggressive toward their own-group juveniles that had been sired by the neighbouring dominant but only when encountered in the neighbouring territory and with a greater bias against female juveniles. Females were least aggressive toward own-group juveniles sired by their own-group dominant male. The sire-bias in tolerance among females is similar to that reported among the dominant males themselves in an earlier study. As a result of the combined sire-bias in tolerance by adult males and females, juveniles sired by their own-group dominant males become less likely to intrude into a neighbouring territory with time. Overall, the results suggest that differences in social tolerance reflect discrimination on the basis of social group membership rather than relatedness between interactants and thus provide strong experimental evidence in support of incidental kin bias rather than kin discrimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167794
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  • 7
    Electronic Resource
    Electronic Resource
    Fluctuating asymmetry and sperm transfer in male decorated field crickets (Gryllodes sigillatus) (2000)
    Springer
    Behavioral ecology and sociobiology 47 (2000), S. 287-292 
    Details
    ISSN: 1432-0762
    Keywords: Key words Fluctuating asymmetry ; Body size ; Sperm ; Spermatophylax ; Gryllodes sigillatus ; Mate choice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Fluctuating asymmetry (FA) in limb size in female decorated field crickets (Gryllodes sigillatus) was associated with a reduction in the size of the spermatophore and the amount of sperm transferred by males and an increase in the time taken to transfer a spermatophore following introduction of a female. There was a weaker negative relationship between limb asymmetry in males and sperm number but no significant relationship between asymmetry in either sex and spermatophylax size. In line with a previous study, female size did not appear to influence spermatophore production or mating decisions by males. The results imply that developmental instability affects both gamete production and mating decisions among males, although the relationships between spermatophore size, sperm number and asymmetry in females are unlikely to be the result of males perceiving differences in female FA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050668
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  • 8
    Electronic Resource
    Electronic Resource
    Prey size selection and competition in the common shrew (Sorex araneus L.) (1981)
    Springer
    Behavioral ecology and sociobiology 8 (1981), S. 239-243 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. We examine the idea that predators may sometimes use a rule of thumb (in this case prey size) to estimate relative prey profitability for optimizing diet selection. We provided adult common shrews with a choice between large and small pieces of mealworm, where large pieces were less profitable than small, because of handling time characteristics. 2. The tendency for animals to prefer large prey depended on their encounter rate with large prey, but was not influenced by variation in encounter rate with small prey once a threshold encounter rate with large (about 0.03 encounters/s) had been reached. 3. We also tested the hypothesis that a predator would be less selective when competing with other animals for food. Shrews showed a significant reduction in selectivity when an apparent ‘competitor’ was present during a test.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299836
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  • 9
    Electronic Resource
    Electronic Resource
    Risk-sensitive foraging in common shrews (Sorex araneus L.) (1985)
    Springer
    Behavioral ecology and sociobiology 16 (1985), S. 161-164 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Risk-sensitive foraging theory predicts that predators which face starvation if there is a temporary shortfall in their food supply should choose feeding sites on the basis of variation in as well as mean expected reward rate. For a given mean reward rate they should choose high variance feeding sites (be risk-prone) if they are running below energy requirement, but low variance sites (be risk-averse) if they are running above. Common shrews presented with a choice between constant and variable feeding stations were more likely to visit the variable station when they were running below energy requirement and more likely to visit the constant station when they were running above. However, the tendency towards risk-aversion above requirement was greater than that towards risk-proneness below. When all shrews were considered together, the probability of visiting the variable station correlated negatively and continuously with intake relative to requirement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295150
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  • 10
    Electronic Resource
    Electronic Resource
    The effects of prior residence, competitive ability and food availability on the outcome of interactions between shrews (Sorex araneus L.) (1982)
    Springer
    Behavioral ecology and sociobiology 10 (1982), S. 307-312 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Interactions between pairs of shrews on a foraging grid were analysed to test for the effects of prior residence, food density and differences in competitive ability between individuals on the outcome. Prior residence was an important factor influencing the outcome of interactions but the degree of resident advantage varied both with food density on the grid and the difference in competitive ability between shrews. Payoff and resource holding power (R.H.P.) asymmetry effects can be implied from the influence of food density and competitive ability differences but prior residence may operate as an uncorrelated asymmetry only under certain conditions determined by combinations of the other two asymmetries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302822
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