Luc-Alain Giraldeau

Publications (121) View all

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  Available from: Luc-Alain Giraldeau

  Dataset: Barrette S & Giraldeau

  Maryse Barrette, Guy Boivin, Jacques Brodeur, Luc-Alain Giraldeau
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  Available from: Luc-Alain Giraldeau

  Dataset: dubois et giraldeau 2007

  Frédérique Dubois, Luc-Alain Giraldeau
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  Available from: Luc-Alain Giraldeau

  Article: Food sharing among retaliators: sequential arrivals and information asymmetries

  Frédérique Dubois, Luc-Alain Giraldeau
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  ABSTRACT: Many animals share food, that is, to tolerate competitors at a defensible clump. Most accounts of resource sharing invoke special evolutionary processes or ecological circumstances that reduce their generality. Surprisingly, the Hawk–Dove game has been unable to address in a simple and general way why so many group foraging animals share food. We modify the Hawk–Dove game by allowing a finder the opportunity of retaliating if joiners escalate and by considering the consequences of information asymmetries concerning resource value among players. Introducing the first change, the retaliator strategy was sufficient to predict widespread sharing in habitats where food clumps are of intermediate richness. When information asymmetry between finder and joiner is created by allowing the quality of clumps to vary, we show that the conditions for sharing are even more easily met and apply to a wider range of resource qualities. Our model therefore offers one of the most parsimonious and potentially general evolutionary accounts of the origin of non-aggressive resource sharing.
  Behavioral Ecology and Sociobiology 04/2012; 62(2):263-271. · 3.18 Impact Factor
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  Available from: Kimberley J. Mathot

  Article: Family-related differences in social foraging tactic use in the zebra finch (Taeniopygia guttata)

  Kimberley J. Mathot, Luc-Alain Giraldeau
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  ABSTRACT: When animals forage in groups, they can search for food themselves (producer tactic), or they can search for opportunities to exploit the food discoveries of others (scrounger tactic). Both theoretical and empirical work have shown that group-level use of these alternative tactics is influenced by environmental conditions including group size and food distribution, and individual tactic use can be influenced by several measures of individual state, including body condition. Because body condition has been shown to be heritable for various species, social foraging tactics may also be heritable. We looked for evidence of heritability in social foraging tactic use in the zebra finch (Taeniopygia guttata) by testing whether: (1) natural variation in body condition correlates with tactic use, (2) there are family-related differences in body condition, and (3) there are family-related differences in observed tactic use. Tactic use in the zebra finch was significantly related to body condition; individuals with lower body condition scores had a significantly higher use of the scrounger tactic as predicted from variance-sensitive producer–scrounger models. Body-condition scores differed significantly between families, suggesting that this aspect of individual state may have a heritable component. Finally, we recorded significant family-related differences in the use of producer and scrounger alternatives. These results are consistent with heritability in observed tactic use resulting from an inheritance of individual state, in this case body condition, which itself influences tactic use. Understanding how and why individuals differ in their use of alternative tactics is fundamental as it may provide important insights into inter-individual variation in fitness. KeywordsSocial foraging-Producer–scrounger-Conditional strategy-Alternative tactics-Family effects-Heritability
  Behavioral Ecology and Sociobiology 04/2012; 64(11):1805-1811. · 3.18 Impact Factor
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  Available from: Luc-Alain Giraldeau

  Article: Travel time affects optimal diets in depleting patches

  Maryse Barrette, Guy Boivin, Jacques Brodeur, Luc-Alain Giraldeau
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  ABSTRACT: Models of prey choice in depleting patches predict an expanding specialist strategy: Animals should start as specialists on the most profitable prey and then at some point during patch exploitation switch to a generalist foraging strategy. When patch residence time is long, the switch to a generalist diet is predicted to occur earlier than when patch residence time is short. We tested these predictions under laboratory conditions using female parasitoids (Aphidius colemani) exploiting patches of mixed instars aphid hosts (Myzus persicae, L1 and L4). The duration of patch exploitation was manipulated by changing travel time between patches. As predicted, patch residence times increase with travel time between patches. Our results provide empirical support for the expanding specialist prediction: Parasitoid females specialized initially on the more profitable hosts (L4), and as the patch depleted, they switched to a generalist diet by accepting more frequently the less profitable hosts (L1). The point at which they switched from specialist to generalist occurred later when travel times and hence patch residence times were short. By affecting the patch exploitation strategy, travel time also determines the composition of hosts left behind, the “giving up composition.” The change in the relative density of remaining host types alters aphid populations’ age structure.
  Behavioral Ecology and Sociobiology 04/2012; 64(4):593-598. · 3.18 Impact Factor