Scordato, E. S., & Drea, C. M. (2007). Scents and sensibility: information content of olfactory signals in the ringtailed lemur, Lemur catta. Anim. Behav., 73(2), 301–314.
Abstract: The function of olfactory signalling in social species is less well understood than in asocial species. Consequently, we examined olfactory communication in the ringtailed lemur, a socially complex primate that retains a functional vomeronasal organ, has well-developed scent glands and shows a suite of scent-marking behaviour. To assess the information content of different types of scent gland secretions, we decoupled olfactory cues from the visual and behavioural modalities with which scent marking is normally associated. We presented male and female subjects (signal receivers) with a series of choice tests between odours derived from conspecific donors (signal senders) varying by sex, age, social status and reproductive condition. We additionally examined the influence of the receivers' reproductive state and familiarity with the signaller. The reproductive condition, social status and familiarity of senders and receivers affected signal transmission; specifically, male receivers attended most to the odours of conspecifics in breeding condition and to the odours of familiar, dominant animals. By contrast, females varied their responses according to both their own reproductive state and that of the sender. Based on male and female patterns of countermarking, we suggest that scent marking serves a function in intergroup spacing and intrasexual competition for both sexes, as might be expected in a female-dominant species. By contrast, minimal female interest in male odours counters a female mate choice function for scent marking in this species. Nevertheless, scent marks are critical to male-male competition and, therefore, may be subject to sexual selection.
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Nakagawa, S., & Waas, J. R. (2004). 'O sibling, where art thou?' – A review of avian sibling recognition with respect to the mammalian literature. Biological Reviews of the Cambridge Philosophical Society, 79(1), 101–119.
Abstract: Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where 'mixing potential' of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through 'direct familiarisation' (commonly known as associative learning or familiarity); future experiments should also incorporate tests for 'indirect familiarisation' (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic.
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Drummond, H. (2006). Dominance in vertebrate broods and litters. Quarterly Review of Biology, 81(1), 3–32.
Abstract: Drawing on the concepts and theory of dominance in adult vertebrates, this article categorizes the relationships of dominance between infant siblings, identifies the behavioral mechanisms that give rise to those relationships, and proposes a model to explain their evolution. Dominance relationships in avian broods can be classified according to the agonistic roles of dominants and subordinates as “aggression-submission,” “aggression-resistance, ” “aggression-aggression,” “aggression-avoidance,” “rotating dominance,” and “flock dominance.” These relationships differ mainly in the submissiveness/pugnacity of subordinates, which is pivotal, and in the specificity/generality of the learning processes that underlie them. As in the dominance hierarchies of adult vertebrates, agonistic roles are engendered and maintained by several mechanisms, including differential fighting ability, assessment, trained winning and losing (especially in altricial species), learned individual relationships (especially in precocial species), site-specific learning, and probably group-level effects. An evolutionary framework in which the species-typical dominance relationship is determined by feeding mode, confinement, cost of subordination, and capacity for individual recognition, can be extended to mammalian litters and account for the aggression-submission and aggression-resistance observed in distinct populations of spotted hyenas and the “site-specific dominance” (teat ownership) of some pigs, felids, and hyraxes. Little is known about agonism in the litters of other mammals or broods of poikilotherms, but some species of fish and crocodilians have the potential for dominance among broodmates. Copyright © 2006 by The University of Chicago. All rights reserved.
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Bates, L. A., Sayialel, K. N., Njiraini, N. W., Poole, J. H., Moss, C. J., & Byrne, R. W. (2008). African elephants have expectations about the locations of out-of-sight family members. Biol Lett, 4(1), 34–36.
Abstract: Monitoring the location of conspecifics may be important to social mammals. Here, we use an expectancy-violation paradigm to test the ability of African elephants (Loxodonta africana) to keep track of their social companions from olfactory cues. We presented elephants with samples of earth mixed with urine from female conspecifics that were either kin or unrelated to them, and either unexpected or highly predictable at that location. From behavioural measurements of the elephants' reactions, we show that African elephants can recognize up to 17 females and possibly up to 30 family members from cues present in the urine-earth mix, and that they keep track of the location of these individuals in relation to themselves.
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Crowley, P. H., Provencher, L., Sloane, S., Dugatkin, L. A., Spohn, B., Rogers, L., et al. (1996). Evolving cooperation: the role of individual recognition. Biosystems, 37(1-2), 49–66.
Abstract: To evaluate the role of individual recognition in the evolution of cooperation, we formulated and analyzed a genetic algorithm model (EvCo) for playing the Iterated Prisoner's Dilemma (IPD) game. Strategies compete against each other during each generation, and successful strategies contribute more of their attributes to the next generation. Each strategy is encoded on a `chromosome' that plays the IPD, responding to the sequences of most recent responses by the interacting individuals (chromosomes). The analysis reported in this paper considered different memory capabilities (one to five previous interactions), pairing continuities (pairs of individuals remain together for about one, two, five, or 1000 consecutive interactions), and types of individual recognition (recognition capability was maximal, nil, or allowed to evolve between these limits). Analysis of the results focused on the frequency of mutual cooperation in pairwise interactions (a good indicator of overall success in the IPD) and on the extent to which previous responses by the focal individual and its partner were associated with the partner's identity (individual recognition). Results indicated that a fixed, substantial amount of individual recognition could maintain high levels of mutual cooperation even at low pairing continuities, and a significant but limited capability for individual recognition evolved under selection. Recognition generally increased mutual cooperation more when the recent responses of individuals other than the current partner were ignored. Titrating recognition memory under selection using a fitness cost suggested that memory of the partner's previous responses was more valuable than memory of the focal's previous responses. The dynamics produced to date by EvCo are a step toward understanding the evolution of social networks, for which additional benefits associated with group interactions must be incorporated.
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