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Dugatkin, L. A., & Alfieri, M. (1991). Guppies and the TIT FOR TAT strategy: preference based on past interaction. Behav. Ecol. Sociobiol., 28(4), 243–246.
Abstract: The evolution of cooperation requires either (a) nonrandom interactions, such that cooperators preferentially interact with other cooperators, or (b) conditional behaviors, such that individuals act cooperatively primarily towards other cooperators. Although these conditions can be met without assuming sophisticated animal cognition, they are more likely to be met if animals can remember individuals with whom they have interacted, associate past interactions with these individuals, and base future behavior on this information. Here we show that guppies (Poecilia reticulata), in the context of predator inspection behavior, can identify and remember (for at least 4 h) the “more cooperative” among two conspecifics and subsequently choose to be near these individuals in future encounters.
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Dugatkin, L. A. (2001). Bystander effects and the structure of dominance hierarchies. Behav. Ecol., 12(3), 348–352.
Abstract: Prior modeling work has found that pure winner and loser effects (i.e., changing the estimation of your own fighting ability as a function of direct prior experience) can have important consequences for hierarchy formation. Here these models are extended to incorporate “bystander effects.” When bystander effects are in operation, observers (i.e., bystanders) of aggressive interactions change their assessment of the protagonists' fighting abilities (depending on who wins and who loses). Computer simulations demonstrate that when bystander winner effects alone are at play, groups have a clear omega (bottom-ranking individual), while the relative position of other group members remains difficult to determine. When only bystander loser effects are in operation, wins and losses are randomly distributed throughout a group (i.e., no discernible hierarchy). When pure and bystander winner effects are jointly in place, a linear hierarchy, in which all positions (i.e., {alpha} to {delta} when N = 4) are clearly defined, emerges. Joint pure and bystander loser effects produce the same result. In principle one could test the predictions from the models developed here in a straightforward comparative study. Hopefully, the results of this model will spur on such studies in the future.
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Dugatkin, L. A. (1992). Tendency to inspect predators predicts mortality risk in the guppy (Poecilia reticulata). Behav. Ecol., 3(2), 124–127.
Abstract: Although predator inspection behavior in fishes has become a model system for examining game theoretical strategies such as Tit for Tat, the direct costs of inspection behavior have not been quantified. To begin quantifying such costs, I conducted an experiment that examined mortality due to predation as a function of predator inspection in the guppy (Poecilia reticulata). Before being subjected to a “survivorship” experiment, guppies were assayed for their tendency to inspect a predator. Groups were then composed of six guppies that differed in their tendency to inspect. These groups were placed into a pool containing a predator, and survivorship of guppies with different inspection tendencies was noted 36 and 60 h later. Results indicate that individuals that display high degrees of inspection behavior suffer greater mortality than their noninspecting shoalmates.
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Dugatkin, L. A. (1997). Winner and loser effects and the structure of dominance hierarchies. Behav. Ecol., 8(6), 583–587.
Abstract: In the literature on dominance hierarchies, “winner” and “loser” effects usually are denned as an increased probability of winning at time T, bated on victories at time T-l, T-2, etc, and an increased probability of losing at time T, based on losing at T-1, T-2, etc., respectively. Despite some early theoretical work on winner and loser effects, these factors and how they affect the structure of dominance hierarchies have not been examined in detail. I developed a computer simulation to examine winner and loser effects when such effects are independent of one another (as well as when they interact) and when combatants assess each other's resource-holding power. When winner effects alone were important, a hierarchy in which all individuals held an unambiguous rank was found. When only loser effects were important, a dear alpha individual always emerged, but the rank of others in the group was often unclear because of the scarcity of aggressive interactions. Increasing winner effects for a given value of the loser effect increase the number of individuals with unambiguous positions in a hierarchy and the converse is true for increasing the value of the loser effect for a given winner effect Although winner and loser effects have been documented in a number of species, no study has documented both winner and loser effects (using some controlled, pairwise testing system) and the detailed nature of behavioral interactions when individuals are in groups. I hope the results of this model will spur such studies in the future.
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Dugatkin, L. A. (1991). Dynamics of the TIT FOR TAT strategy during predator inspection in the guppy (Poecilia reticulata). Behav. Ecol. Sociobiol., 29(2), 127–132.
Abstract: One well-known solution to the iterated Prisoner's Dilemma is the TIT FOR TAT strategy. This strategy has three “characteristics” associated with it. TIT FOR TAT is nice (cooperates on the first move of a game), retaliatory (plays defect against an individual that defected on the prior move), and forgiving (cooperates with an individual which has defected in the past but cooperates in the present). Predator inspection behavior in guppies (Poecilia reticulata) was examined in order to determine whether guppies displayed these three characteristics. Results indicate that while it can be quite difficult to translate the abstract concepts of niceness, retaliation, and forgiveness into measurable behaviors, the data support the hypothesis that guppies display the three characteristics associated with the TIT FOR TAT strategy.
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Doutrelant, C., McGregor, P. K., & Oliveira, R. F. (2001). The effect of an audience on intrasexual communication in male Siamese fighting fish, Betta splendens. Behav. Ecol., 12, 283–286.
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Dingemanse, N. J., & de Goede, P. (2004). The relation between dominance and exploratory behavior is context-dependent in wild great tits. Behav. Ecol., 15(6), 1023–1030.
Abstract: Individual differences in personality affect behavior in novel or challenging situations. Personality traits may be subject to selection because they affect the ability to dominate others. We investigated whether dominance rank at feeding tables in winter correlated with a heritable personality trait (as measured by exploratory behavior in a novel environment) in a natural population of great tits, Parus major. We provided clumped resources at feeding tables and calculated linear dominance hierarchies on the basis of observations between dyads of color-ringed individuals, and we used an experimental procedure to measure individual exploratory behavior of these birds. We show that fast-exploring territorial males had higher dominance ranks than did slow-exploring territorial males in two out of three samples, and that dominance related negatively to the distance between the site of observation and the territory. In contrast, fast-exploring nonterritorial juveniles had lower dominance ranks than did slow-exploring nonterritorial juveniles, implying that the relation between dominance and personality is context-dependent in the wild. We discuss how these patterns in dominance can explain earlier reported effects of avian personality on natal dispersal and fitness.
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Cant, M. A., & Field, J. (2005). Helping effort in a dominance hierarchy. Behav. Ecol., 16(4), 708–715.
Abstract: In many cooperatively breeding species, group members form a dominance hierarchy or queue to inherit the position of breeder. Models aimed at understanding individual variation in helping behavior, however, rarely take into account the effect of dominance rank on expected future reproductive success and thus the potential direct fitness costs of helping. Here we develop a kin-selection model of helping behavior in multimember groups in which only the highest ranking individual breeds. Each group member can invest in the dominant's offspring at a cost to its own survivorship. The model predicts that lower ranked subordinates, who have a smaller probability of inheriting the group, should work harder than higher ranked subordinates. This prediction holds regardless of whether the intrinsic mortality rate of subordinates increases or decreases with rank. The prediction does not necessarily hold, however, where the costs of helping are higher for lower ranked individuals: a situation that may be common in vertebrates. The model makes two further testable predictions: that the helping effort of an individual of given rank should be lower in larger groups, and the reproductive success of dominants should be greater where group members are more closely related. Empirical evidence for these predictions is discussed. We argue that the effects of rank on stable helping effort may explain why attempts to correlate individual helping effort with relatedness in cooperatively breeding species have met with limited success.
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Cameron, E. Z., Linklater, W. L., Stafford, K. J., & Minot, E. O. (2000). Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser? Behav. Ecol. Sociobiol., 47(4), 243–249.
Abstract: In many mammalian species, female success in raising offspring improves as they age. The residual reproductive value hypothesis predicts that each individual offspring will be more valuable to the mother as she ages because there is less conflict between the current and potential future offspring. Therefore, as mothers age, their investment into individual offspring should increase. Empirical evidence for an influence of declining residual reproductive value on maternal investment is unconvincing. Older mothers may not invest more, but may be more successful due to greater experience, allowing them to target their investment more appropriately (targeted reproductive effort hypothesis). Most studies do not preclude either hypothesis. Mare age significantly influenced maternal investment in feral horses living on the North Island of New Zealand. Older mares, that were more successful at raising foals, were more protective for the first 20 days of life, but less diligent thereafter. Total maternal input by older mothers did not seem to be any greater, but was better targeted at the most critical period for foal survival and a similar pattern was observed in mares that had lost a foal in the previous year. In addition, older mothers were more likely to foal in consecutive years, supporting the hypothesis that they are investing less than younger mares in individual offspring. Therefore, older mothers seem to become more successful by targeting their investment better due to experience, not by investing more in their offspring.
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Cameron, E. Z.,, Linklater, W. L.,, Stafford, K. J.,, & Minot, E. O.,. (2003). Social grouping and maternal behaviour in feral horses (Equus caballus): the influence of males on maternal protectiveness. Behav. Ecol. Sociobiol., 53(2), 92–101.
Abstract: The risk of infant injury or mortality influences maternal behaviour, particularly protectiveness. Mares are found in bands with a single stallion or bands with more than one stallion in which paternity is less certain. We investigated maternal behaviour in relation to band type. Mares in bands with more than one stallion were more protective of their foals, particularly when stallions and foals approached one another. The rate of aggression between the stallion and foal was a significant predictor of maternal protectiveness, and mare protectiveness was significantly correlated with reduced reproductive success in the subsequent year. Mares that changed band types with a foal at foot, or had their band type experimentally altered, were more protective of their foal in multi-stallion bands than they were in single-stallion bands. Equids are unusual amongst ungulates in that infanticide and feticide have been reported. Both occur where paternity has been uncertain, and equid social structure is similar to other species in which infanticide has been reported. Stallions benefit from infanticide as the mare has greater reproductive success in the subsequent year. Stallion aggression is a significant modifier of mare behaviour and maternal effort, probably due to the risk of infanticide.
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