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Purvis, A. (2006). The h index: playing the numbers game. Trends. Ecol. Evol, 21(8), 422.
Abstract: Article Outline
References
The ‘h index’ was developed recently as a measure of research performance [1]: a researcher's h is the number of his or her papers that have been cited at least h times. In their thoughtful critique of the index, Kelly and Jennions [2] point out many ways in which h is no better than ‘traditional’ bibliometrics, such as total citation counts. However, there is one way in which, for researchers, it could be very much better, especially if (as Hirsch suggests [1]) it is to inform hiring and promotion decisions. The skewed nature of the distribution of citations among publications means that most researchers have several papers that nearly but not quite count. Consequently, h can be distorted much more easily than can total citation count just by finding a subtle way to cite one's own papers that are ‘bubbling under’. Incidentally, bats show broadly the same life-history allometries as other mammalian clades [3].
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Rands, S. A., Cowlishaw, G., Pettifor, R. A., Rowcliffe, J. M., & Johnstone, R. A. (2008). The emergence of leaders and followers in foraging pairs when the qualities of individuals differ. BMC Evol Biol, 8, 51.
Abstract: BACKGROUND: Foraging in groups offers animals a number of advantages, such as increasing their likelihood of finding food or detecting and avoiding predators. In order for a group to remain together, there has to be some degree of coordination of behaviour and movement between its members (which may in some cases be initiated by a decision-making leader, and in other cases may emerge as an underlying property of the group). For example, behavioural synchronisation is a phenomenon where animals within a group initiate and then continue to conduct identical behaviours, and has been characterised for a wide range of species. We examine how a pair of animals should behave using a state-dependent approach, and ask what conditions are likely to lead to behavioural synchronisation occurring, and whether one of the individuals is more likely to act as a leader. RESULTS: The model we describe considers how the energetic gain, metabolic requirements and predation risks faced by the individuals affect measures of their energetic state and behaviour (such as the degree of behavioural synchronisation seen within the pair, and the value to an individual of knowing the energetic state of its colleague). We explore how predictable changes in these measures are in response to changes in physiological requirements and predation risk. We also consider how these measures should change when the members of the pair are not identical in their metabolic requirements or their susceptibility to predation. We find that many of the changes seen in these measures are complex, especially when asymmetries exist between the members of the pair. CONCLUSION: Analyses are presented that demonstrate that, although these general patterns are robust, care needs to be taken when considering the effects of individual differences, as the relationship between individual differences and the resulting qualitative changes in behaviour may be complex. We discuss how these results are related to experimental observations, and how the model and its predictions could be extended.
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List, C. (2004). Democracy in animal groups: a political science perspective. Trends Ecol Evol, 19(4), 168–169.
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Lusseau, D. (2007). Evidence for social role in a dolphin social network. Evol. Ecol., 21(3), 357–366.
Abstract: Abstract Social animals have to take into consideration the behaviour of conspecifics when making decisions to go by their daily lives. These decisions affect their fitness and there is therefore an evolutionary pressure to try making the right choices. In many instances individuals will make their own choices and the behaviour of the group will be a democratic integration of everyone’s decision. However, in some instances it can be advantageous to follow the choice of a few individuals in the group if they have more information regarding the situation that has arisen. Here I provide early evidence that decisions about shifts in activity states in a population of bottlenose dolphin follow such a decision-making process. This unshared consensus is mediated by a non-vocal signal, which can be communicated globally within the dolphin school. These signals are emitted by individuals that tend to have more information about the behaviour of potential competitors because of their position in the social network. I hypothesise that this decision-making process emerged from the social structure of the population and the need to maintain mixed-sex schools.
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Wilson, S. D., Clark, A. B., Coleman, K., & Dearstyne, T. (1994). Shyness and boldness in humans and other animals. Trends. Ecol. Evol, 9(11), 442–446.
Abstract: The shy-bold continuum is a fundamental axis of behavioral variation in humans and at least some other species, but its taxonomic distribution and evolutionary implications are unknown. Models of optimal risk, density- or frequency-dependent selection, and phenotypic plasticity can provide a theoretical framework for understanding shyness and boldness as a product of natural selection. We sketch this framework and review the few empirical studies of shyness and boldness in natural populations. The study of shyness and boldness adds an interesting new dimension to behavioral ecology by focusing on the nature of continuous behavioral variation that exists within the familiar categories of age, sex and size.
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Bergmüller, R. (2010). Animal Personality and Behavioural Syndromes. In P. Kappeler (Ed.), Animal Behaviour – Evolution and Mechanisms (pp. 587–621). Heidelberg: Springer.
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van Schaik, C. P. (2010). Social learning and culture in animals. In P. Kappeler (Ed.), Animal Behaviour: Evolution and Mechanisms (pp. 623–653). Springer Berlin Heidelberg.
Abstract: Most animals must learn some of the behaviours in their repertoire, and some must learn most. Although learning is often thought of as an individual exercise, in nature much learning is social, i.e. under the influence of conspecifics. Social learners acquire novel information or skills faster and at lower cost, but risk learning false information or useless skills. Social learning can be divided into learning from social information and learning through social interaction. Different species have different mechanisms of learning from social information, ranging from selective attention to the environment due to the presence of others to copying of complete motor sequences. In vertical (or oblique) social learning, naïve individuals often learn skills or knowledge from parents (or other adults), whereas horizontal social learning is from peers, either immatures or adults, and more often concerns eavesdropping and public information use. Because vertical social learning is often adaptive, maturing individuals often have a preference for it over individual exploration. The more cognitively demanding social learning abilities probably evolved in this context, in lineages where offspring show long association with parents and niches are complex. Because horizontal learning can be maladaptive, especially when perishable information has become outdated, animals must decide when to deploy social learning. Social learning of novel skills can lead to distinct traditions or cultures when the innovations are sufficiently rare and effectively transmitted socially. Animal cultures may be common but to date taxonomic coverage is insufficient to know how common. Cultural evolution is potentially powerful, but largely confined to humans, for reasons currently unknown. A general theory of culture is therefore badly needed.
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Pusey, A. E. (1987). Sex-biased dispersal and inbreeding avoidance in birds and mammals. Trends. Ecol. Evol, 2(10), 295–299.
Abstract: Sex differences in dispersal distance are widespread in birds and mammals, but the predominantly dispersing sex differs consistently between the classes. There has been persistent debate over the relative importance of two factors -- intrasexual competition and inbreeding avoidance -- in producing sex-biased dispersal, and over the sources of the difference in dispersal patterns between the two classes. Recent studies cast new light on these questions.
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Kerth, G. (2010). Group decision-making in animal societies. In P. Kappeler (Ed.), Animal Behaviour: Evolution and Mechanisms (pp. 241–265). Springer Berlin Heidelberg.
Abstract: Individuals need to coordinate their activities to benefit from group living. Thus group decisions are essential for societies, especially if group members cooperate with each other. Models show that shared (democratic) decisions outperform unshared (despotic) decisions, even if individuals disagree about actions. This is surprising as in most other contexts, differences in individual preferences lead to sex-, age-, or kin-specific behaviour. Empirical studies testing the predictions of the theoretical models have only recently begun to emerge. This applies particularly to group decisions in fission-fusion societies, where individuals can avoid decisions that are not in their interest. After outlining the basic ideas and theoretical models on group decision-making I focus on the available empirical studies. Originally most of the relevant studies have been on social insects and fish but recently an increasing number of studies on mammals and birds have been published, including some that deal with wild long-lived animals living in complex societies. This includes societies where group members have different interests, as in most mammals, and which have been less studied compared to eusocial insects that normally have no conflict among their colony members about what to do. I investigate whether the same decision rules apply in societies with conflict and without conflict, and outline open questions that remain to be studied. The chapter concludes with a synthesis on what is known about group decision-making in animals and an outlook on what I think should be done to answer the open questions.
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Connor, R. C. (1995). Altruism among non-relatives: alternatives to the 'Prisoner's Dilemma'. Trends Ecol Evol, 10(2), 84–86.
Abstract: Triver's model of reciprocal altruism, and its descendants based on the Prisoner's Dilemma model, have dominated thinking about cooperation and altruism between non-relatives. However, there are three alternative models of altruism directed to non-relatives. These models, which are not based on the Prisoner's Dilemma, may explain a variety of phenomena, from allogrooming among impala to helping by non-relatives in cooperatively breeding birds and mammals.
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