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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.10.014 Byline: Nobuyuki Kutsukake (a)(b)(c), Tim H. Clutton-Brock (a) Abstract: In social mammals, grooming is used not only for hygienic purposes; it also serves social functions. We examined the grooming patterns of dominant males in groups of cooperatively breeding meerkats, Suricata suricatta, to test the hypothesis that the distribution of grooming reflects the value of social relationships. Grooming between dominant individuals was the most commonly observed interaction. Grooming by the dominant male was less common when the dominant female was in oestrus. Grooming between dominant males and subordinates was asymmetrical, with dominant males receiving more grooming and providing less grooming to subordinates. Because subordinate males defend the group against extragroup males, the dominant male was predicted to groom subordinate males more often than to groom subordinate females. Although the sex of a subordinate did not affect the probability of grooming occurring, dominant males groomed subordinate males for longer than they groomed subordinate females. The duration of grooming by a dominant male was longer in small groups than large groups, suggesting that grooming activity is constrained by time. In contrast, subordinates groomed dominant males for longer in larger groups, and as a result, the asymmetry of grooming exchanges was exaggerated in larger groups. This result is consistent with the biological market theory, which predicts that the value of subordinates is dependent on group size and that subordinates will alter grooming efforts accordingly. These results suggest that meerkat grooming serves several social functions, such as the maintenance of valuable and/or fitness-enhancing relationships. Author Affiliation: (a) Large Animal Research Group, Department of Zoology, University of Cambridge, U.K. (b) Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, Japan (c) PRESTO, Japan Science and Technology Agency, Japan Article History: Received 2 February 2009; Revised 26 February 2009; Accepted 5 October 2009 Article Note: (miscellaneous) MS. number: 09-00070R

Explanations of cooperation between non-kin in animal societies often suggest that individuals exchange resources or services and that cooperation is maintained by reciprocity. But do cooperative interactions between unrelated individuals in non-human animals really resemble exchanges or are they a consequence of simpler mechanisms? Firm evidence of reciprocity in animal societies is rare and many examples of cooperation between non-kin probably represent cases of intra-specific mutualism or manipulation., As Darwin appreciated, cooperative behaviour--actions adapted to assist others that involve costs to the fitness of participants--poses a fundamental problem to the traditional theory of natural selection, which rests on [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.03.011 Byline: Joah R. Madden (a), Hans-Joerg P. Kunc (b), Sinead English (a), Tim H. Clutton-Brock (a) Abstract: Begging by young provokes adults to provide food for them. However, eventually begging by young and provisioning by adults cease and young become nutritionally independent. Why do young cease begging and so forgo food brought to them by adults? Three explanations have been proposed: (1) adults may not respond to begging anymore and cease feeding begging young; (2) young may voluntarily switch from begging to independent foraging as they gain more rewards from this; (3) young may become unable to produce stimulating begging calls. We tested these three explanations using meerkat, Suricata suricatta, pups. Playback of begging calls at groups where begging had naturally ceased provoked adults to resume provisioning, suggesting that adults had not stopped responding to begging. Experimental provision of food to pups mimicking either natural pup feeding or foraging success produced no differences in subsequent changes in begging or foraging behaviour, suggesting that pups were not assessing the most rewarding means of obtaining food and switching from begging to foraging accordingly. The begging calls of pups (aged 40-60 days) were acoustically different to those produced when they were juveniles (aged 100-120 days), and adults discriminated between rate-controlled playbacks of the two age classes of calls, delivering less food to calls of a juvenile than to the same individual's calls recorded when a pup. Adult meerkats paid attention to the acoustic structure of begging calls, and ceased provisioning when the call structure changed. We suggest that older pups are unable to produce stimulating begging calls. Author Affiliation: (a) Large Animal Research Group, Department of Zoology, University of Cambridge, U.K. (b) Verhaltensbiologie, Zoologisches Institut, Universitat Zurich-Irchel, Switzerland Article History: Received 4 December 2008; Revised 19 January 2009; Accepted 27 March 2009 Article Note: (miscellaneous) MS. number: 08-00775R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.08.026 Byline: Tim Clutton-Brock Abstract: Darwin developed the theory of sexual selection to account for the evolution of weaponry, ornamentation and other secondary sexual characters that are commonly more developed in males and which appeared unlikely to contribute to survival. He argued that these traits had evolved either through intrasexual competition between males to monopolize access to females or through consistent female preferences for mating with superior partners. Since 1871, a substantial body of research has confirmed his explanation of the evolution of secondary sexual characters in males, although sex differences in reproductive behaviour are more diverse and the evolutionary mechanisms responsible for them are more complex than was initially recognized. However, secondary sexual characters are also widespread in females but, as yet, their evolution and distribution have received relatively little attention from evolutionary biologists. Here, I suggest that the mechanisms responsible for the evolution of secondary sexual characters in females are similar to those operating in males and include intrasexual competition between females for breeding opportunities, male mating preferences and female competition to attract mates. Unlike males, females often compete more intensely for resources necessary for successful reproduction than for access to mating partners and the development of secondary sexual characters in females may be limited by costs to fecundity rather than to survival. Author Affiliation: Department of Zoology, University of Cambridge, U.K. Article History: Received 28 April 2008; Revised 25 May 2008; Accepted 27 August 2008 Article Note: (miscellaneous) MS. number: 08-00267

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.07.027 Byline: Marta B. Manser, Joah R. Madden, Hansjoerg P. Kunc, Sinead English, Tim Clutton-Brock Abstract: In many bird species with biparental care for young in the nest, hungry chicks beg repeatedly and parents adjust their feeding rate to the call rate of young. Repetitive calling also occurs in fledglings and in some mammals where offspring follow provisioners. It is not yet clear whether, in mobile systems with dispersed young where adults cannot compare the vocal behaviour of all young simultaneously, the calls represent a signal of need. We investigated repetitive begging by cooperatively reared meerkat, Suricata suricatta, pups that foraged with the group. Pups produced two types of begging calls: repeat calls over long periods and high-pitched calls mainly confined to feeding events. Food-deprived pups stayed closer to feeders, and begged for longer and more intensely by calling at a higher rate. Hungry pups increased both the rate of repeat calls, which were given continually, and the number of high-pitched bouts, but adults increased their food allocation only in relation to the rate of repeat calls. Our study indicates that hunger may lead to several changes in vocal behaviour, only some of which may be used by adults to assess need. Author Affiliation: (a) Verhaltensbiologie, Zoologisches Institut, Universitat Zurich, Switzerland (a ) Mammal Research Institute, University of Pretoria, South Africa (a ) Department of Zoology, University of Cambridge, U.K. Article History: Received 8 January 2008; Revised 14 March 2008; Accepted 29 July 2008 Article Note: (miscellaneous) MS. number: 08-00015R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2007.09.018 Byline: Nobuyuki Kutsukake, Tim H. Clutton-Brock Abstract: Group-living primates and other animals use postaggression (PA) behavioural strategies to reduce the social costs of aggression. However, the relative frequency with which individuals use these conflict management strategies is unclear in many species, and functional analyses of these behaviours are rare. We observed aggression by dominant individuals against group members in cooperatively breeding meerkats, Suricata suricatta, and examined the incidents and effects of PA affiliation between the opponents (reconciliation), avoidance and submission. Aggression had a negative effect on the social relationship between opponents because of an elevated probability of aggression occurrence and an increased time interval until the first nonagonistic PA encounter compared to nonagonistic (control) encounters. The probability of aggression reoccurrence did not decrease with increasing time interval until the first PA encounter, indicating that aggression had long-lasting negative effects on social relationships. Evidence of reconciliation following aggression was not confirmed in this species. Avoidance and submission by the victim characterized the social behaviour following aggression. Although avoidance by victims in the first PA encounter reduced the probability of aggression reoccurrence, submission during aggression neither reduced the probability of aggression reoccurrence nor shortened the time interval until the first PA encounter. These results suggest that avoidance is the only behavioural option for victims of aggression to deal with PA hostility. Reconciliation and other forms of conflict management may be more important in species with low reproductive skew and with opportunities for negotiating relationships between group members than in despotic singular cooperative breeders. Author Affiliation: (a) Large Animal Research Group, Department of Zoology, University of Cambridge, U.K. (a ) Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, Japan Article History: Received 12 January 2007; Revised 2 March 2007; Accepted 27 September 2007 Article Note: (miscellaneous) MS. number: 9232R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2006.02.016 Byline: Nobuyuki Kutsukake, Tim H. Clutton-Brock Abstract: In social mammals, grooming may be used in care of offspring, to maintain pair bonds, or to placate dominant individuals. We examined grooming patterns in groups of the cooperatively breeding meerkat, Suricata suricatta. Dominant females produce over 80% of litters, but older subordinate females occasionally breed. Grooming between dominant individuals was the most common and symmetrical interaction. The dominant female received more and gave less in grooming interactions with subordinates. The dominant female groomed younger subordinates more frequently than older subordinates, suggesting that grooming by dominant females represents parental care, and also reflects the reproductive conflict between females. Older subordinates groomed the dominant female more frequently than did younger subordinates. Subordinates that were frequently attacked by the dominant female groomed her for longer durations than those that were not, and the duration of dominant female grooming by subordinates increased as birth of the dominant female's pups approached. These results support the idea that subordinates use grooming to placate the dominant female. Analysis of 'immediate reciprocity' (whether the groomee returned grooming of the groomer within the grooming bout) showed that subordinate females reciprocated more frequently than subordinate males when the dominant female initiated grooming. However, the dominant female reciprocated subordinate females less frequently than she did subordinate males. This suggests that the need to placate the dominant female may be higher for subordinate females than for subordinate males, possibly because of the risk of eviction caused by reproductive conflict between females. Author Affiliation: (a) Large Animal Research Group, Department of Zoology, University of Cambridge, U.K. (a ) Department of Biological Science, Graduate School of Sciences, University of Tokyo, Japan Article History: Received 19 September 2005; Revised 25 October 2005; Accepted 25 February 2006 Article Note: (miscellaneous) MS. number: 8679

Knowledge of relatedness between pairs of individuals plays an important role in many research areas including evolutionary biology, quantitative genetics, and conservation. Pairwise relatedness estimation methods based on genetic data from highly variable molecular markers are now used extensively as a substitute for pedigrees. Although the sampling variance of the estimators has been intensively studied for the most common simple genetic relationships, such as unrelated, half- and full-sib, or parent--offspring, little attention has been paid to the average performance of the estimators, by which we mean the performance across all pairs of individuals in a sample. Here we apply two measures to quantify the average performance: first, misclassification rates between pairs of genetic relationships and, second, the proportion of variance explained in the pairwise relatedness estimates by the true population relatedness composition (i. e., the frequencies of different relationships in the population). Using simulated data derived from exceptionally good quality marker and pedigree data from five long-term projects of natural populations, we demonstrate that the average performance depends mainly on the population relatedness composition and may be improved by the marker data quality only within the limits of the population relatedness composition. Our five examples of vertebrate breeding systems suggest that due to the remarkably low variance in relatedness across the population, marker-based estimates may often have low power to address research questions of interest.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2005.01.019 Byline: Andrew J. Young, Anne A. Carlson, Tim Clutton-Brock Abstract: Males commonly face a trade-off between investment in offspring care and time spent seeking additional breeding opportunities. Although this trade-off is central to our understanding of the evolution of male parental care, it has been largely ignored by studies of male alloparental care in cooperative societies, where male helpers could face a similar problem. We investigated whether male helpers in cooperative societies of meerkats Suricata suricatta trade off their cooperative contributions to pup feeding against extraterritorial prospecting for mating and dispersal opportunities. Not only did male helpers spend extended periods away from the group during pup care periods, but those that spent most time prospecting also contributed least to pup feeding when present in the group. Regular prospectors lost the most weight over the pup-feeding period and male testosterone levels increased in association with prospecting. As both reduced body condition and elevated testosterone have been shown to compromise the expression of offspring care, these findings provide likely explanations for the reduced pup-feeding rates of regular prospectors. Despite their lapses in contributions to cooperative activities, we found no evidence for punishment of prospectors by other group members, suggesting that helpers are able to adjust their contributions according to their own optima. These findings reveal that male helpers in cooperative species can face similar trade-offs to male parents in noncooperative species, between investment in offspring care and alternative fitness-maximizing tactics such as prospecting. We discuss the broader implications of this work for our understanding of both individual variation and sex differences in contributions to cooperative behaviour. Author Affiliation: Department of Zoology, University of Cambridge, U.K. Article History: Received 1 October 2004; Revised 18 November 2004; Accepted 19 January 2005 Article Note: (miscellaneous) MS. number: 8292

In cooperatively breeding vertebrates, nonbreeding helpers raise young produced by dominant breeders. Although the evolution of cooperative breeding has often been attributed primarily to kin selection (whereby individuals gain 'indirect' benefits to their fitness by assisting collateral relatives), there is increasing evidence that helpers can be unrelated to the young they are raising. Recent studies also suggest that the indirect benefits of cooperative behavior may often have been overestimated while the direct benefits of helping to the helper's own fitness have probably been underestimated. It now seems likely that the evolutionary mechanisms maintaining cooperative breeding are diverse and that, in some species, the direct benefits of helping may be sufficient to maintain cooperative societies. The benefits of cooperation in vertebrate societies may consequently show parallels with those in human societies, where cooperation between unrelated individuals is frequent and social institutions are often maintained by generalized reciprocity., Kin selection (1) is widely thought to play a dominant role in the evolution of specialized cooperative societies, where breeding individuals rely on the assistance of nonbreeding helpers to raise [...]