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Bayly, K. L., Evans, C. S., & Taylor, A. (2006). Measuring social structure: A comparison of eight dominance indices. Behav. Process., 73(1), 1–12.
Abstract: Measurement of social status is an important component of many behavioural studies. A variety of techniques have been developed and adopted, but while there have been some analyses of index properties using simulated data, the rationale for selecting a method remains poorly documented. As a first step in exploring the implications of index choice, we compared the characteristics of eight popular indices by applying each to the same data set from interactions between male fowl Gallus gallus, the system in which social hierarchies were first described. Data from eight social groups, observed over four successive breeding seasons, were analysed to determine whether different indices produced consistent dominance scores. These scores were then used in tests of the relation between social status and crowing to explore whether index choice affected the results obtained. We also examined the pattern of dominance index use over the last decade to infer whether this has likely been influenced by tradition, or by taxa of study animal. Overall agreement among methods was good when groups of birds had perfectly linear hierarchies, but results diverged when social structure was more complex, with either intransitive triads or reversals. While all regression analyses revealed a positive relationship between dominance and vocal behaviour, there were substantial differences in the amount of variance accounted for, even though the original data were identical in every case. Index selection can hence perturb estimates of the importance of dominance, relative to other factors. We also found that several methods have been adopted only by particular research teams, while the use of others has been taxonomically constrained, patterns implying that indices have not always been chosen solely upon their merits. Taken together, our results read as a cautionary tale. We suggest that selection of a dominance index requires careful consideration both of algorithm properties and of the factors affecting social status in the system of interest.
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Hartmann, E., Søndergaard, E., & Keeling, L. J. (2012). Identifying potential risk situations for humans when removing horses from groups. Appl. Anim. Behav. Sci., 136(1), 37–43.
Abstract: Removing a horse from its social group may be considered risky, both for the handler and the horse, because other horses can interfere in the catching process. The main aim of this study was to identify where and when these risk situations occur while removing a horse from its group. A potential risk situation was defined by the closeness of loose horses in the group or by any physical contact with them. Whether the number of horses following would be influenced by the social rank of the horse being led out, and whether more horses would follow to the gate when a larger proportion of the group was removed compared to when a single horse was taken out were also investigated. Thirty-two mares (1–2 years) were kept in groups of four. All horses were taken out of their home paddock twice alone (64 tests) and twice with a companion (32 tests). One handler (or two handlers when two horses were removed) was asked to approach (phase 1) and catch the target horse (phase 2), walk it to the centre of the paddock and remain stationary at a post for 30 s (phase 3), walk to the paddock entrance (phase 4) and through the gate (phase 5). The number of horses following, and the number of loose horses in proximity (<2 m, 2–5 m) to the target horse and handler was estimated, and horse–horse and horse–human interactions were recorded continuously for the five scoring phases. Significantly more loose horses were within 2 m of a single target horse during the phases approach (mean ± SD: 1.5 ± 0.8), catch (1.6 ± 0.9) and post (1.7 ± 0.7) than during walk (1.0 ± 0.5) and gate (1.1 ± 0.6). Rank did not influence the number of horses following to the gate (high rank: 2.4 ± 0.7; lower rank: 2.0 ± 1.0; P = 0.396) and interactions between horses were rare. A greater proportion of the loose horses followed when two horses (0.9 ± 0.2) were removed compared to when a single horse (0.7 ± 0.3) was taken out (P = 0.011). In conclusion, maintaining a distance to other horses in the group by reducing the time being relatively stationary, so giving loose horses fewer chances to approach, is likely to contribute to improved handler's safety. Removing a small proportion of the group may also decrease the probability of the other horses following.
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Croneya, C. C. (2007). Group size and cognitive processes. Appl. Anim. Behav. Sci., 103(3-4), 15–228.
Abstract: Animal group sizes may exert important effects on various cognitive mechanisms. Group
size is believed to exert pressures on fundamental brain structures that correlate with the
increased social demands placed on animals living in relatively large, complex and dynamic
social organizations. There is strong experimental evidence connecting social complexity,
social learning and development of other cognitive abilities in a broad range of wild and
domesticated animal species. In particular, group size seems to have significant effects on
animals? abilities to derive concrete and abstract relationships. Here, we review the literature
pertaining to cognitive processes and behaviours of various animal species relative to group
size, with emphasis on social learning. It is suggested that understanding the relationship
between group size and cognition in animals may yield practical animal management
benefits, such as housing and conservation strategies, and may also have implications for
improved animal welfare.
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Kihara, H., Nakatani, H., Hiromi, K., & Hon-Nami, K. (1977). Kinetic studies on redox reactions of hemoproteins. I. Reduction of thermoresistant cytochrome c-552 and horse heart cytochrome c by ferrocyanide. Biochim Biophys Acta, 460(3), 480–489.
Abstract: The oxidation-reduction reaction of horse heart cytochrome c and cytochrome c (552, Thermus thermophilus), which is highly thermoresistant, was studied by temperature-jump method. Ferrohexacyanide was used as reductant. (Formula: see text.) Thermodynamic and activation parameters of the reaction obtained for both cytochromes were compared with each other. The results of this showed that (1) the redox potential of cytochrome c-552, + 0.19 V, is markedly less than that of horse heart cytochrome c. (2) deltaHox of cytochrome c-552 is considerably lower than that of horse heart cytochrome c. (3) deltaSox and deltaSred of cytochrome c-552 are more negative than those of horse heart cytochrome c. (4) kred of cytochrome c-552 is much lower than that of horse heart cytochrome c at room temperature.
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Knopff, K., & Pavelka, M. (2006). Feeding Competition and Group Size in Alouatta pigra. Int. J. Primatol., 27(4), 1059–1078.
Abstract: Researchers consider group size in primates to be determined by complex relationships among numerous ecological forces. Antipredator benefits and better resource defense are the primary pressures for large groups. Conversely, intragroup limited food availability, can result in greater intragroup feeding competition and individual energy expenditure in larger groups, creating energetic advantages for individuals in small groups and placing an upper limit group size. However, the extent to which food availability constrains group size remains unclear for many species, including black howlers (Alouatta pigra), which ubiquitously live in small social groups (≤10 individuals). We studied the relationship between group size and 2 key indices of feeding competition-day journey length and activity budgets in 3 groups of wild Alouatta pigra at a hurricane-damaged site in Belize, Central America. We controlled for differences in food availability between home ranges (food tree density) and compared both indicators of feeding competition directly with temporal variation in food availability for each group. Our results show no consistent association between resource availability, group size, and either index of competition, indicating that feeding competition does not limit group size at the site i.e., that larger groups can form without increased costs of feeding competition. The results support the search for other explanations, possibly social ones, for small group size in the primates, and we conclude with suggestions and evidence for such alternative explanations.
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Barton, R. A., Byrne, R. W., & Whiten, A. (1996). Ecology, feeding competition and social structure in baboons. Behav. Ecol. Sociobiol., 38(5), 321–329.
Abstract: Predictions of the model of van Schaik (1989) of female-bonding in primates are tested by systematically comparing the ecology, level of within-group contest competition for food (WGC), and patterns of social behaviour found in two contrasting baboon populations. Significant differences were found in food distribution (percentage of the diet from clumped sources), feeding supplant rates and grooming patterns. In accord with the model, the tendencies of females to affiliate and form coalitions with one another, and to be philopatric, were strongest where ecological conditions promoted WGC. Group fission in the population with strong WGC was “horizontal” with respect to female dominance rank, and associated with female-female aggression during a period of elevated feeding competition. In contrast, where WGC was low, females' grooming was focused on adult males rather than other females. Recent evidence suggests that group fission here is initiated by males, tends to result in the formation of one-male groups, and is not related to feeding competition but to male-male competition for mates. An ecological model of baboon social structure is presented which incorporates the effects of female-female competition, male-male competition, and predation pressure. The model potentially accounts for wide variability in group size, group structure and social relationships within the genus Papio. Socio-ecological convergence between common baboons and hamadryas baboons, however, may be limited in some respects by phylogenetic inertia.
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Dugatkin, L. A., & Godin, G. J. (1992). Predator inspection, shoaling and foraging under predation hazard in the Trinidadian guppy,Poecilia reticulata. Environmental Biology of Fishes, 34(3), 265–276.
Abstract: Guppies,Poecilia reticulata, living in stream pools in Trinidad, West Indies, approached a potential fish predator (a cichlid fish model) in a tentative, saltatory manner, mainly as singletons or in pairs. Such behavior is referred to as predator inspection behavior. Inspectors approached the trunk and tail of the predator model more frequently, more closely and in larger groups than they approached the predator's head, which is presumably the most dangerous area around the predator. However, guppies were not observed in significantly larger shoals in the stream when the predator model was present. In a stream enclosure, guppies inspected the predator model more frequently when it was stationary compared to when it was moving, and made closer inspections to the posterior regions of the predator than to its head. Therefore, the guppies apparently regarded the predator model as a potential threat and modified their behavior accordingly when inspecting it. Guppies exhibited a lower feeding rate in the presence of the predator, suggesting a trade-off between foraging gains and safety against predation. Our results further suggest that predator inspection behavior may account for some of this reduction in foraging. These findings are discussed in the context of the benefits and costs of predator inspection behavior.
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Hagen, S. J., & Eaton, W. A. (2000). Two-state expansion and collapse of a polypeptide. J Mol Biol, 301(4), 1019–1027.
Abstract: The initial phase of folding for many proteins is presumed to be the collapse of the polypeptide chain from expanded to compact, but still denatured, conformations. Theory and simulations suggest that this collapse may be a two-state transition, characterized by barrier-crossing kinetics, while the collapse of homopolymers is continuous and multi-phasic. We have used a laser temperature-jump with fluorescence spectroscopy to measure the complete time-course of the collapse of denatured cytochrome c with nanosecond time resolution. We find the process to be exponential in time and thermally activated, with an apparent activation energy approximately 9 k(B)T (after correction for solvent viscosity). These results indicate that polypeptide collapse is kinetically a two-state transition. Because of the observed free energy barrier, the time scale of polypeptide collapse is dramatically slower than is predicted by Langevin models for homopolymer collapse.
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Keiper, R., & Houpt, K. (1984). Reproduction in feral horses: an eight-year study. Am J Vet Res, 45(5), 991–995.
Abstract: The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area.
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Cambefort, J. P. (1981). A comparative study of culturally transmitted patterns of feeding habits in the chacma baboon Papio ursinus and the vervet monkey Cercopithecus aethiops. Folia Primatol (Basel), 36(3-4), 243–263.
Abstract: Japanese workers have studied social acquisition patterns of new feeding habits in Macaca fuscata which they have termed precultural. The present study investigates the same phenomenon in the chacma baboon and the vervet monkey in their natural habitat. The questions addressed are: (1) How a new feeding habit enters a troop and by which age and sex category, also how it is propagated? (2) When individuals are permitted with a choice between palatable and unpalatable food, can they learn by demonstration only or do they have to pass through a direct learning process? (3) Can the results from the above questions be explained by social parameters such as the social structure of the individual species? It was found that juvenile baboons discover new food and that after the discovery propagation is instantaneous. In vervets discovery is random among the age classes and propagation is slow and takes place through certain 'pivot' individuals. Both species fail to learn about palatability by demonstration but have to go through a direct learning process. This contrasts strongly with the forest baboon Mandrillus sphinx that have been shown to learn by demonstration. Socially, baboon juveniles stay closer to each other than the adults who force them to live at the periphery of the troop. Vervets again forage without precise sub-group formation. The link between social and cultural propagation and social structure is discussed on the basis of these findings.
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