Phyllis C. Lee

Fission-Fusion Dynamics: New Research Frameworks

Renewed interest in fission‐fusion dynamics is due to the recognition that such dynamics may create unique challenges for social interaction and distinctive selective pressures acting on underlying communicative and cognitive abilities. New frameworks for integrating current knowledge on fission‐fusion dynamics emerge from a fundamental rethinking of the term “fission‐fusion” away from its current general use as a label for a particular modal type of social system (i.e., “fission‐fusion societies”). Specifically, because the degree of spatial and temporal cohesion of group members varies both within and across taxa, any social system can be described in terms of the extent to which it expresses fission‐fusion dynamics. This perspective has implications for socioecology, communication, cognitive demands, and human social evolution.

Allomothering among African elephants

Abstract Elephant, Loxodonta africana, calves are born into stable family units, with a variety of partners with whom they can interact. In a population of elephants with known lineages and calf ages, interactions between calves and other elephants were found to be frequent and consisted of either relaxed, friendly greetings and investigations of others or assistance when calves were threatened or distressed. Juvenile and adolescent females comforted, assisted and protected calves; these females were defined as allomothers. Allomothers tended to be family members but were not always siblings. Siblings maintained close proximity to calves, while calf defence also involved less closely related family members. The early establishment of close caretaking relationships within families may act to enhance the stability of the family through time. Suckling of calves by non-mothers was extremely rare, and unlikely to enhance the nutritional intake of calves.

Behavioral correlates of non-random mortality among free-ranging female vervet monkeys

SummaryOver a 3.5 year period, illness and predation operated in a non-random manner on free-ranging vervet monkeys in Amboseli National Park. As a result, there was no correlation among adult females between dominance rank and reproductive success. Deaths due to illness were concentrated among low-ranking individuals, and appeared to occur as a result of restricted access to food and water during the dry season. In contrast, deaths due to predation were concentrated among high-ranking individuals. The precise cause of such increased vulnerability could not be determined.High-ranking females alarm-called at higher frequencies than low-ranking females, and were also more aggressive than low-ranking females during intergroup encounters. In contrast, low-ranking females were more likely to initiate friendly interactions with the members of other groups. The non-random distribution of causes of mortality suggests that individuals living in the same social group may confront different selective pressures. Perhaps as a result, individuals appear to respond differently to similar social and environmental variables.

Reproductive parameters and maternal investment in mandrills (Mandrillus sphinx)

We report on 14 years of reproductive data for semifree-ranging mandrills (Mandrillus sphinx) in Gabon, and we explore relationships between female rank, age and parity, and reproductive strategies. Most births (61% of 132) occurred during the wet season in Gabon, between January and March. Female rank and parity were unrelated to the timing of parturition. Gestation lengths average 175 days (SE = ±1 day; N = 61) and were similar irrespective of female rank, parity, or sex of offspring. Birth sex ratio did not differ significantly from unity (52% male), and was unrelated to maternal rank or parity. Stillbirths and neonatal mortality tended to be more common among lower-ranking females than among either mid-ranking or dominant females. Median age at first birth is 4.71 years, at a median body mass of 7.6 kg, ca 5 years before females attain their adult body mass (median 12 kg). Age at first reproduction is significantly correlated with dominance rank, with dominant females giving birth on average 1.3 years earlier than lower-ranking females do. Interbirth intervals (IBI) average 405 days (range 184–1159 days, N = 103), and are independent of the sex of the offspring. Infant death within 6 months shortened IBI to 305 days. Increasing age and parity are also associated with short IBI, as is higher rank. Maternal rank and parity appear to influence reproductive success in female mandrills, but there is no apparent differential maternal investment by sex.

Behavioural inbreeding avoidance in wild African elephants

The costs of inbreeding depression, as well as the opportunity costs of inbreeding avoidance, determine whether and which mechanisms of inbreeding avoidance evolve. In African elephants, sex‐biased dispersal does not lead to the complete separation of male and female relatives, and so individuals may experience selection to recognize kin and avoid inbreeding. However, because estrous females are rare and male–male competition for mates is intense, the opportunity costs of inbreeding avoidance may be high, particularly for males. Here we combine 28 years of behavioural and demographic data on wild elephants with genotypes from 545 adult females, adult males, and calves in Amboseli National Park, Kenya, to test the hypothesis that elephants engage in sexual behaviour and reproduction with relatives less often than expected by chance. We found support for this hypothesis: males engaged in proportionally fewer sexual behaviours and sired proportionally fewer offspring with females that were natal family members or close genetic relatives (both maternal and paternal) than they did with nonkin. We discuss the relevance of these results for understanding the evolution of inbreeding avoidance and for elephant conservation.

People and protected areas: a study of local perceptions of wildlife crop-damage conflict in an area bordering the Selous Game Reserve, Tanzania

This paper presents an analysis of perceived patterns of wildlife crop-damage in relation to an on-farm assessment of damage in an area bordering the Selous Game Reserve (SGR) in south-eastern Tanzania. Data from an attitudinal questionnaire survey of 202 households in four villages are used to examine local perceptions of wildlife crop-damage in terms of relative impact and which wildlife species were responsible. We explore the influence of wildlife crop-damage on attitudes to the adjacent game reserve. Data on the frequency of crop-damage events and estimated severity of impacts, recorded during a 6-month programme of crop-damage monitoring in one of the survey villages, are used to describe on-farm patterns of crop-damage. Comparison of the two data sets indicates a disjunction between the nature of the wildlife crop-damage conflict as perceived by local villagers, and as it actually occurs in the study area. This disjunction is discussed in relation to the effect of extreme damage events on local peoples views, the opportunity costs involved in guarding farm plots against crop-damage, and the tenure arrangements for wildlife that define the relationship with the state wildlife management authority.

Association patterns of African elephants in all-male groups: the role of age and genetic relatedness

Strong social bonds are uncommon among male mammals. In many mammals, however, males form all-male groups, providing opportunities for male–male bonds to emerge. We examined association patterns of male African elephants, Loxodonta africana, in all-male groups and assessed the influence of age and genetic relatedness on these associations. We also examined the influence of age and genetic relatedness on the choice of sparring partners in male elephants. Males had many weak and random associations and few valuable relationships. Male associations were positively correlated with genetic relatedness, suggesting that kinship influences patterns of male associations. Male associations were negatively correlated with age disparity, and males were more likely to spar with other males closer in age to themselves. These results suggest that males associate with other males of similar age in part because sparring may facilitate the development and maintenance of motor and psychological responses to sudden and unexpected events that occur during play; this may help prepare males for male–male competition. We also found that older males had high centrality and strength in social networks, suggesting that older males influence the cohesion of male social groups. Consequently, the elimination of older males from elephant populations by poachers or trophy hunters could negatively affect social cohesion in male elephant groups. Finally, we found that age and genetic relatedness were not significantly correlated, suggesting that male associations based on age and relatedness did not overlap. These findings highlight the complexity of male social relationships in all-male groups.

Grooming reciprocity in wild male chimpanzees

Understanding cooperation between unrelated individuals remains a central problem in animal behaviour; evolutionary mechanisms are debated, and the importance of reciprocity has been questioned. Biological market theory makes specific predictions about the occurrence of reciprocity in social groups; applied to the social grooming of mammals, it predicts reciprocity in the absence of other benefits for which grooming can be exchanged. Considerable effort has been made to test this grooming trade model in nonhuman primates; such studies show mixed results, but may be confounded by kin effects. We examined patterns of reciprocity within and across bouts, and tested predictions of the grooming trade model, among wild male chimpanzees, Pan troglodytes: a system with negligible kin effects. In accord with the model’s expectations, we found that some grooming was directed by lower- to higher-ranked individuals, and that, on average, higher-ranked individuals groomed more reciprocally. We found no support, however, for a prediction that more reciprocity should occur between individuals close in rank. For most dyads, reciprocity of effort occurred through unbalanced participation in grooming bouts, but reciprocity varied considerably between dyads and only a small proportion showed strongly reciprocal grooming. Despite this, each male had at least one reciprocal grooming relationship. In bouts where both individuals groomed, effort was matched through mutual grooming, not alternating roles. Our results provide mixed support for the current grooming trade, biological market model, and suggest that it needs to incorporate risks of currency inflation and cheating for species where reciprocity can be achieved through repeated dyadic interactions. 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. Altruistic acts are behaviours that benefit the recipient at an apparent cost to the actor (Trivers 1971). The theory of reciprocal altruism holds that such acts can evolve by natural selection if the roles of actor and recipient are reciprocated such that both incur costs (albeit offset in time) and obtain net fitness benefits. Evidence for the role of this ‘direct reciprocity’ in shaping altruistic behaviour among animal species is limited, however (Clutton-Brock 2009). Originally modelled using the Prisoner’s Dilemma (Trivers 1971), increasingly sophisticated game-theoretical approaches have been developed to accommodate more realistic assumptions. In the Prisoner’s Dilemma, individuals are constrained into interacting with a particular partner, and have only a choice between cooperation or noncooperation, with the value of cooperation equal to both partners (Trivers 1971). In contrast, for animals living in social groups, choice of partners for social interactions is common (Wilkinson 1984; Noe et al. 1991; Emery 2004; Connor 2007;

Personality structure in brown capuchin monkeys (Sapajus apella): comparisons with chimpanzees (Pan troglodytes), orangutans (Pongo spp.), and rhesus macaques (Macaca mulatta).

Species comparisons of personality structure (i.e., how many personality dimensions and the characteristics of those dimensions) can facilitate questions about the adaptive function of personality in nonhuman primates. Here we investigate personality structure in the brown capuchin monkey (Sapajus apella), a New World primate species, and compare this structure to those of chimpanzees (Pan troglodytes), orangutans (Pongo spp.), and rhesus macaques (Macaca mulatta). Brown capuchins evolved behavioral and cognitive traits that are qualitatively similar to those of great apes, and individual differences in behavior and cognition often reflect differences in personality. Thus, we hypothesized that brown capuchin personality structure would overlap more with great apes than with rhesus macaques. We obtained personality ratings from seven sites, including 127 brown capuchin monkeys. Principal-components analysis identified five personality dimensions (Assertiveness, Openness, Neuroticism, Sociability, and Attentiveness), which were reliable across raters and, in a subset of subjects, significantly correlated with relevant behaviors up to a year later. Comparisons between species revealed that brown capuchins and great apes overlapped in personality structure, particularly chimpanzees in the case of Neuroticism. However, in some respects (i.e., capuchin Sociability and Openness) the similarities between capuchins and great apes were not significantly greater than those between capuchins and rhesus macaques. We discuss the relevance of our results to brown capuchin behavior and the evolution of personality structure in primates.

Elephants, ivory, and trade.

Trade decisions made by the Convention on International Trade in Endangered Species must place science over politics. Tanzania and Zambia are petitioning the Convention on International Trade in Endangered Species (CITES) to “downlist” the conservation status of their elephants to allow sale of stockpiled ivory. But just 2 years after CITES placed a 9-year moratorium on future ivory sales (1), elephant poaching is on the rise. The petitioning countries are major sources and conduits of Africas illegal ivory (2–4). The petitions highlight the controversy surrounding ivory trade (5) and broader issues underlying CITES trade decisions.