The evolution of female social relationships in nonhuman primates

Considerable interspecifc variation in female social relationships occurs in gregarious primates, par- ticularly with regard to agonism and cooperation be- tween females and to the quality of female relationships with males. This variation exists alongside variation in female philopatry and dispersal. Socioecological theories have tried to explain variation in female-female social relationships from an evolutionary perspective focused on ecological factors, notably predation and food dis- tribution. According to the current ``ecological model'', predation risk forces females of most diurnal primate species to live in groups; the strength of the contest component of competition for resources within and be- tween groups then largely determines social relationships between females. Social relationships among gregarious females are here characterized as Dispersal-Egalitarian, Resident-Nepotistic, Resident-Nepotistic-Tolerant, or Resident-Egalitarian. This ecological model has suc- cessfully explained differences in the occurrence of for- mal submission signals, decided dominance relation- ships, coalitions and female philopatry. Group size and female rank generally affect female reproduction success as the model predicts, and studies of closely related species in different ecological circumstances underscore the importance of the model. Some cases, however, can only be explained when we extend the model to incor- porate the effects of infanticide risk and habitat satura- tion. We review evidence in support of the ecological model and test the power of alternative models that in- voke between-group competition, forced female phi- lopatry, demographic female recruitment, male inter- ventions into female aggression, and male harassment. Not one of these models can replace the ecological model, which already encompasses the between-group competition. Currently the best model, which explains several phenomena that the ecological model does not, is a ``socioecological model'' based on the combined im- portance of ecological factors, habitat saturation and infanticide avoidance. We note some points of similarity and divergence with other mammalian taxa; these re- main to be explored in detail

Environmental influences on mountain gorilla time budgets

Data on the time budgets of mountain gorillas ( Gorilla gorilla beringei ) were collected during field studies in the Virunga Volcanoes region of Rwanda and Zaire. Focal sampling was used to determine the proportion of time that individuals of different age/sex classes spent in several mutually exclusive activity states. The gorillas spent the majority of daylight hours feeding; most of the rest of the day was devoted to resting, with little time spent moving or engaged in social activity. The time budget varied among the different subhabitats used by the gorillas, and the gorillas satisfied subsistence needs more quickly when in areas where food was more abundant and/or of better nutritional quality. Silverbacks spent more time feeding than all other age/sex classes, but age/sex class differences were not great. All age/sex classes responded to variability in habitat quality in similar fashion. Unlike the case for many other primates, there was no significant seasonal variation in time budgets. There was a direct relationship between group size and time spent feeding, although variation in relation to group size was lower than that in relation to variation in habitat quality. These results are consistent with the relationship of feeding time to body size in primates. They are also consistent, with other evidence that social foraging entails a cost to gorilla females, but that this cost is low in comparison to those faced by many other primates. Permanent association with males apparently offers little ecological disadvantage to females, who are likely to be more than compensated by mutualistic benefits.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38424/1/1350150303_ftp.pd

Comparative Feeding Ecology of Two Chimpanzee Communities in Kibale National Park (Uganda)

Several recent studies have documented considerable intraspecific and intrapopulation ecological variation in primates. However, we generally lack an understanding of how such variability may be linked to concomitant demographic variation among groups and/or populations of the same species, particularly in regards to large-bodied and wide-ranging species with high ecological flexibility, such as chimpanzees (Pan troglodytes). We compared the feeding ecology of chimpanzees inhabiting two sites in Kibale National Park, Uganda that differ three-fold in chimpanzee density and support notably different plant communities. Chimpanzees at Ngogo, a site with the largest known chimpanzee community and unusually high chimpanzee density, spent a significantly lower percentage of time resting (and pregnant and lactating females spent more time feeding), incorporated higher percentages of ripe fruit in their diet, had lower dietary diversity values, and had shorter and less variable average patch residency times than did their counterparts at the nearby Kanyawara site, which supports a relatively low density of chimpanzees. Additionally, feeding party size was significantly and positively related to feeding patch size at Ngogo, but not at Kanyawara. Together these findings aid in explaining the noted disparity in chimpanzee community size and density between Ngogo and Kanyawara by suggesting that the diet of Ngogo chimpanzees is of higher overall quality than that of Kanyawara chimpanzees. They also highlight the potentially profound influence of even small-scale habitat heterogeneity on the ecology of primates. Researchers must take such influences into account when attempting to draw conclusions about species- or population-level characteristics.Human Evolutionary Biolog

Ant eating behavior of mountain gorillas

Eleven cases of feeding on driver ants ( Dorylus sp.) by mountain gorillas ( Gorilla gorilla beringei ) are described. Ant eating provides the gorillas with more animal protein and other nutrients per unit feeding time than do other forms of insectivory that contribute to their diet, but it is so rare that it is unlikely to be of real nutritional significance. Gorillas obtain ants with their hands and do not use tools. Immature individuals (except infants) ate more ants than did adult females, and silverbacks were not seen to eat ants. These differences are more likely to reflect differences in individual taste and interest in novelty than differences in nutritional strategy. Not all gorillas in the Virungas population eat ants. Intra-population variability may be ecologically contingent, but ant eating appears to be a socially acquired and transmitted taste.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41604/1/10329_2006_Article_BF02381219.pd

Fitting the Professional to the Job: Idealism and Realism

This article examines a number of factors related to job satisfaction among financial aid professionals. How well the job matches the individual\u27s expectations of employment, regardless of intrinsic or extrinsic job orientation, accounts for the greater proportion of explained job satisfaction. The implications of these findings for management of financial aid offices are discussed. An earlier version of this paper was presented to the Southwestern Sociological Association

Minimum income for healthy living and frailty in adults over 65 years old in the English Longitudinal Study of Ageing: a population-based cohort study

Objective To test whether minimum income for healthy living of a person aged 65 years or older (MIHL₆₅) is associated with frailty in older adults. Design and setting Secondary analysis of the English Longitudinal Study of Ageing, a multiwave prospective cohort study in England, UK. Participants A subset (n=1342) of English Longitudinal Study of Ageing participants, who at wave 1 in 2002 were aged 65 years or older, without any limiting long-standing illnesses, and who had the information required to calculate MIHL₆₅ in 2002, 2004 and 2006 and two measures of frailty in 2008. Main outcome measures Frailty defined using Fried’s phenotype criteria and Rockwood’s Index of deficits. Results The odds of frailty in 2008 were significantly higher for participants living below MIHL₆₅ in 2002, both on Fried’s phenotype criteria (OR 2.56, 95% CI 1.57 to 4.19) and Rockwood’s Index (OR 2.83, 95% CI 1.74 to 4.60). These associations remained after adjustment for age and gender for both Fried’s phenotype (OR 1.85, 95% CI 1.18 to 2.90) and Rockwood’s Index (OR 2.15, 95% CI 1.38 to 3.35). Compared with those whose income during 2002–2006 was always above MIHL₆₅, the odds of frailty in 2008 for those below MIHL₆₅ were two-to-three times higher, with a tendency for the ORs to increase in line with the length of time spent below MIHL₆₅ (ORs (95% CIs) were: Fried’s phenotype, below MIHL₆₅ once: 2.02 (1.23 to 3.34); twice: 2.52 (1.37 to 4.62); thrice: 3.53 (1.65 to 7.55). Rockwood’s Index: once: 2.34 (1.41 to 3.86); twice: 3.06 (1.64 to 5.71); thrice: 2.56 (1.22 to 5.34)). These associations remained after adjustment for age and gender on Rockwood’s Index, but not Fried’s phenotype. Conclusions These results provide some support for the idea that frailty at older ages is associated with not having sufficient income to lead a healthy life

Diet of chimpanzees ( Pan troglodytes schweinfurthii ) at Ngogo, Kibale National Park, Uganda, 1. diet composition and diversity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90275/1/ajp21016.pd