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Results for “Competitive Behavior”

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PubMed1985

A statistical reevaluation of the STAI anxiety questionnaire.

This study examined the capability and efficiency of two commonly used scales, the trait and trait and state inventories (Spielberger et al., 1970), to measure anxiety construct (N = 100). The probabilistic Rasch Model (Wright & Masters, 1982) was applied to athletes' responses to trait and state anxiety items before competition (stress). The analysis indicated that several items of both scales produce misfit responses, share identical locations on the continuum, and do not produce equal units of measurement. The findings question the generalizability of the research on anxiety. Recommendations for improving the anxiety tests are made.

Adult↗

PubMedDate not supplied

Adsorption of organic compounds onto activated carbons from recycled vegetables biomass.

The removal of organic species from aqueous solution by activated carbons is investigated. The latter ones are prepared from olive husks and almond shells. A wide range of surface area values are obtained varying temperature and duration of both carbonization and activation steps. The adsorption isotherm of phenol, catechol and 2,6-dichlorophenol involving the activated carbons prepared are obtained at 25 degrees C. The corresponding behavior is quantitatively correlated using classical isotherm, whose parameters are estimated by fitting the equilibrium data. A two component isotherm (phenol/2,6-dichlorophenol) is determined in order to test activated carbon behavior during competitive adsorption.

Adsorption↗

PubMed2006

One-male units and clans in a colony of hamadryas baboons (Papio hamadryas hamadryas): effect of male number and clan cohesion on feeding success.

In the multilevel societies of hamadryas baboons, adult males can be attached to single one-male units (OMUs) or to clans containing several such OMUs. This paper examines the effect of male number and rivalry between males within a clan on their ability to compete for access to a clumped food resource. The data come from a study of a multilevel colony of hamadryas baboons (Papio hamadryas hamadryas) housed at the Madrid Zoo. The colony consisted of 12 harem-holding males and 40 sexually mature females, and was organized into five single OMUs and two clans (containing three and four OMUs, respectively). The top-ranking male of one of the clans was removed and later reintroduced, so the study involved an analysis of the composition of clans and OMUs and of the males' use of the feeding area across three study periods: preseparation, separation, and reintroduction. The findings reported indicate that both males and females derived clear advantages in the context of contest competition for access to clumped food if they were members of clans, because the males and females from large clans had a feeding advantage over those from smaller clans and single OMUs. Furthermore, rivalry among males within the clan reduced their ability to compete for food against males outside their clan. This paper provides empirical evidence for one of the potential advantages that hamadryas males may enjoy if they are attached to clans, and also provides empirical support for the general hypothesis that a large number of males in a group may provide fitness-related benefits to the group members, provided they are able to cooperate with each other.

Animals↗

PubMed2007

Partner effects on food consumption in brown capuchin monkeys.

It has been claimed that capuchin monkeys (Cebus apella) show inequity aversion in relation to food rewards for a simple exchange task. However, other factors may affect the willingness of a monkey to consume foods of high or low value in the presence of a conspecific. In this study, pairs of monkeys were presented with unequally valued foods, but without any task-performance: they simply received the food under four experimental conditions. By looking at the rate of collection and consumption of low-valued cucumber slices we expected to see variation dependent on whether the partner either had 1) cucumber (equity), 2) grape (inequity), 3) inaccessible cucumber or 4) inaccessible grape. Testing 12 adult capuchin monkeys, our findings differed from those of other authors in that the monkeys failed to show negative reactions to inequity, but rather responded with scramble competition (i.e., fast food collection) in the presence of a conspecific without access to food. They also showed facilitated consumption in the presence of a conspecific consuming high-valued food. Possibly, (in)equity plays a different role if food serves as a reward for a task rather than if it is simply made available for consumption.

Analysis of Variance↗

PubMed2005

Competition, predation, and the evolutionary significance of the cercopithecine cheek pouch: the case of Cercopithecus and Lophocebus.

Reports of cercopithecine cheek pouch use and functional significance are largely anecdotal, and to date there have been no investigations into its use by species living in closed forest habitats. Here, I report on cheek pouch use in Cercopithecus ascanius and Lophocebus albigena in the Kibale National Park, Uganda, between July-October 1997. Two hypotheses were evaluated: this feature was selected for because of its role in 1) increasing feeding efficiency via a reduction in potential feeding competition, and/or 2) reducing vulnerability to predation. Results indicate that both species were more likely to use their cheek pouches when feeding on contestable foods and, after filling cheek pouches, retreated to more densely vegetated ("safer") positions for processing food. There was no influence of age and sex on L. albigena cheek pouch use. Subadult C. ascanius cheek-pouched less frequently than adults, although there were no differences between adult males and females. There was no relationship between feeding-patch size and number of plant food items cheek-pouched in either species. However, the diameter of breast height (dbh; a measure of patch size) of trees in which C. ascanius used their cheek pouches was significantly larger than the dbh of trees in which they did not. Both species were more likely to use their cheek pouches in the presence of greater numbers of conspecifics. These data provide insight into the relationship(s) among oral anatomy and feeding efficiency, and facilitate understanding into the selection for this important oral feature in stem cercopithecines.

Adaptation, Physiological↗

PubMed2005

Bioarchaeological evidence for trophy-taking in prehistoric central California.

Fourteen adult burials in a large (N = 224) prehistoric central California cemetery (CA-SCL-674) lack forearm bones. Twelve of these otherwise well-articulated primary interments have distal humeri bearing cutmarks with a distribution like that seen in fur seals butchered by Native Californians. Most of the burials with missing forearms are young adult males, a demographic profile that differs significantly from the full sample. Three of these males show evidence of perimortem trauma in addition to forearm amputation. Drilled and polished human radii and ulnae were recovered from the CA-SCL-674 cemetery in archaeological contexts separate from burials with missing forearms. A warfare-related trophy-taking practice is strongly suggested by these bioarchaeological data. Based on these data, it seems likely that 20% (N = 10) or more of the adult males (N = 59) in this population were victims of violence. Evidence of perimortem violence was much less common among women, with only about 2% (N = 2) of adult females (N = 86) subjected to trophy-taking. Examination of museum collections produced further evidence for perimortem forearm amputation among the Native American inhabitants of this area during the transition between the Early and Middle periods. The emergence of more hierarchical social systems during this period may have fostered warfare-related trophy-taking as a symbolic tool for enhancing the power and prestige of individuals within competing social groups.

Adolescent↗

PubMed2006

Male competition and paternity in wild chimpanzees of the Taï forest.

In social animals, competition among males for mates affects individual reproductive success. The priority-of-access model attempts to account for the influence of demographic conditions within groups upon male reproductive success, but empirical data for testing this model are scarce. Our long-term study of chimpanzees in the Taï National Park, Côte d'Ivoire, encompasses a period of steady decrease in community size and fluctuating numbers of competing males and sexually receptive females. These demographic changes, in combination with genetic assessment of paternity for 48 offspring from three communities, allowed us to quantify the effects of varying levels of competition upon male reproductive success. On average, the highest-ranking male sired 50% of all analyzed offspring during a 14-year period from 1987-2000. Competition among males strongly decreased the relative reproductive success of the alpha male, such that the alpha male's rate of success decreased from 67% with few competitors to only 38% with four or more competitors. The increasing number of synchronously receptive females in large groups also reduced the proportion of paternities by the alpha male. Thus, patterns of paternity in Taï chimpanzees fit well the predictions of the priority-of-access model. We also found that despite the inability of dominants to monopolize reproduction, they achieved a higher reproductive rate in large multimale groups, because these have more females and a higher infant survival rate. Varied levels of male competition within communities seem to explain differences in the reproductive success of alpha males observed in different chimpanzee populations, and in other primate species.

Age Factors↗

PubMed2005

Surface-binding autoantibodies to cerebellar neurons in opsoclonus syndrome.

Childhood opsoclonus-myoclonus syndrome can occur with or without associated neuroblastoma. An autoimmune pathogenesis has been discussed for both forms. We show here that the majority of children with opsoclonus-myoclonus syndrome (10/14) have autoantibodies binding to the surface of isolated rat cerebellar granular neurons. In some patients, these antibodies are masked by IgG binding to ubiquitous surface antigens, which could be removed by preincubation with the nonneuronal control cell line HEK 293. A newly introduced competitive binding assay showed that the surface binding is directed against the same autoantigen in different patients. Therefore, we hypothesize that opsoclonus-myoclonus syndrome may be the result of an autoimmune process against a neuronal surface protein.

Antigens, Surface↗

PubMed1963