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Pattison, P., & Wasserman, S. (1999). Logit models and logistic regressions for social networks: II. Multivariate relations. Br J Math Stat Psychol, 52 ( Pt 2), 169–193.
Abstract: The research described here builds on our previous work by generalizing the univariate models described there to models for multivariate relations. This family, labelled p*, generalizes the Markov random graphs of Frank and Strauss, which were further developed by them and others, building on Besag's ideas on estimation. These models were first used to model random variables embedded in lattices by Ising, and have been quite common in the study of spatial data. Here, they are applied to the statistical analysis of multigraphs, in general, and the analysis of multivariate social networks, in particular. In this paper, we show how to formulate models for multivariate social networks by considering a range of theoretical claims about social structure. We illustrate the models by developing structural models for several multivariate networks.
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Hedrick, P. W., Parker, K. M., Miller, E. L., & Miller, P. S. (1999). Major Histocompatibility Complex Variation in the Endangered Przewalski's Horse. Genetics, 152(4), 1701–1710.
Abstract: The major histocompatibility complex (MHC) is a fundamental part of the vertebrate immune system, and the high variability in many MHC genes is thought to play an essential role in recognition of parasites. The Przewalski's horse is extinct in the wild and all the living individuals descend from 13 founders, most of whom were captured around the turn of the century. One of the primary genetic concerns in endangered species is whether they have ample adaptive variation to respond to novel selective factors. In examining 14 Przewalski's horses that are broadly representative of the living animals, we found six different class II DRB major histocompatibility sequences. The sequences showed extensive nonsynonymous variation, concentrated in the putative antigen-binding sites, and little synonymous variation. Individuals had from two to four sequences as determined by single-stranded conformation polymorphism (SSCP) analysis. On the basis of the SSCP data, phylogenetic analysis of the nucleotide sequences, and segregation in a family group, we conclude that four of these sequences are from one gene (although one sequence codes for a nonfunctional allele because it contains a stop codon) and two other sequences are from another gene. The position of the stop codon is at the same amino-acid position as in a closely related sequence from the domestic horse. Because other organisms have extensive variation at homologous loci, the Przewalski's horse may have quite low variation in this important adaptive region. N1 -
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Jezierski, T., Jaworski, Z., & Górecka, A. (1999). Effects of handling on behaviour and heart rate in Konik horses: comparison of stable and forest reared youngstock. Appl. Anim. Behav. Sci., 62(1), 1–11.
Abstract: Thirty foals and young Konik horses born in 3 consecutive years and reared up to weaning either in a forest reserve (R) or conventional stable (S) were compared with respect to behavioural reactions and heart rate (HR) during handling manipulations. The foals were randomly allocated within sex and rearing group to one of two handling treatments. Intensively handled (IH) foals received a 10-min handling, 5 days/week, beginning at the age of 2 weeks (S foals) or 10 months (R foals), and lasting up to the age of 24 months. During handling IH foals were haltered, touched, rubbed and their feet were picked up; non-handled (NH) foals were not handled except for routine or emergency veterinary care. The horses were tested at the age of approximately 6 months (S only) and 12, 18 and 24 months of age. In a test comprising catching the horse on a paddock, leading away from and towards the stable, picking up feet and being approached by an unfamiliar person, the horses' behaviour was scored and the HR was recorded telemetrically. The IH horses scored better as far as manageability behaviour is concerned (P<0.001) and demonstrated lower HR than the NH ones and the S horses scored better than R ones (P<0.001). Fillies demonstrated higher HR than colts (P=0.007). Youngstock of all groups tended to be less manageable at the age of 24 months than at 18 months. Differences between youngstock stemming from particular harems from the reserve seem to be related to differences in accidental contact with people visiting the forest reserve.
Keywords: Handling; Behaviour; Heart rate; Horses; Rearing
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Erhart, E., & Overdorff, D. (1999). Female Coordination of Group Travel in Wild Propithecus and Eulemur. Int. J. Primatol., 20(6), 927-940.
Abstract: Coordination of primate group movements by individual group members is generally categorized as leadership behavior, which entails several steps: deciding where to move next, initiating travel, and leading a group between food, water sources, and rest sites. Presumably, leaders are able to influence their daily foraging efficiency and nutritional intake, which could influence an individual's feeding ecology and long-term reproductive success. Within anthropoid species, females lead group movements in most female-bonded groups, while males lead groups in most nonfemale-bonded groups. Group leadership has not been described for social prosimians, which are typically not female-bonded. We describe group movements in two nonfemale-bonded, lemurid species living in southeastern Madagascar, Propithecus diadema edwardsi and Eulemur fulvus rufus. Although several social lemurids exhibit female dominance Eulemur fulvus rufus does not, and evidence for female dominance is equivocal in Propithecus diadema edwardsi. Given the ecological stresses that females face during reproduction, we predict that females in these two species will implement alternative behavioral strategies such as group leadership in conjunction with, or in the absence of, dominance interactions to improve access to food. We found that females in both species initiated and led group movements significantly more often than males did. In groups with multiple females, one female was primarily responsible for initiating and leading group movements. We conclude that female nutritional needs may determine ranging behavior to a large extent in these prosimian species, at least during months of gestation and lactation.
Keywords: Biomedical and Life Sciences
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McGrew, W., & Marchant, L. (1999). Laterality of hand use pays off in foraging success for wild chimpanzees. Primates, 40(3), 509–513.
Abstract: The aim of this study was to see if behavioral lateralization in hand use benefits a lateralized organism in nature. We recorded wild chimpanzees (Pan troglodytes schweinfurthii) at Gombe, Tanzania, fishing for termites (Macrotermes spp.), an extractive foraging task using elementary technology. We compared individual apes who were completely lateralized, using only one hand or the other for the task, versus those who were incompletely lateralized, using either hand. Exclusively lateralized individuals were more efficient, that is, gathered more prey per unit effort, but were no different in success or error rate from incompletely lateralized apes. This is the first demonstration of a payoff to laterality of behavioral function in primates in conditions of ecological validity.
Keywords: Biomedical and Life Sciences
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Menke, C., Waiblinger, S., Foelsch, D. W., & Wiepkema, P. R. (1999). Social Behaviour and Injuries of Horned Cows in Loose Housing Systems. Anim Welfare, 8(3), 243–258.
Abstract: The relationship between social behaviour and skin injuries (caused by horns) of loose housed horned cows was investigated on 35 dairy farms. While the frequencies of two agonistic behaviour elements (push and chase away) were positively correlated with the occurrence of skin injuries, the frequencies of butting and homing were not. Butting appears to have an ambivalent motivation, in that its occurrence is correlated positively both with agonistic behaviour and with social licking. Horning showed a positive correlation with social licking only. Four groups of husbandry conditions that may be associated with the occurrence of social behaviour and of injuries were distinguished: i) herd management, with variables including problem solving management by the farmer, integration of new cows, and dealing with periparturient and oestrus cows; ii) human-animal relationship, with variables including ability to identify individual cows, frequency of brushing the cows, number of milkers, and frequency of personnel changes; iii) animal characteristics, with the variable of herd size; and iv) stable characteristics, with the variable of space per cow (m2). The relevance of the husbandry variables investigated here had been confirmed in a previous stepwise regression analysis (Menke 1996). The variables for herd management and human-animal relationship conditions correlated in a consistent way with the occurrence of agonistic behaviour and/or of injuries, while most of them also correlated in the opposite direction with the occurrence of social licking. Herd size correlated positively with agonistic behaviour, but negatively with social licking. Space per cow correlated negatively with agonistic behaviour and injuries. In more than 70 per cent of the herds investigated, the levels of agonistic behaviour and of skin injuries were low, implying that horned dairy cows can be kept with less risk than is often assumed. We argue that such risks strongly depend on management factors that can be improved.
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Hopster, H., van der Werf, J. T., Erkens, J. H., & Blokhuis, H. J. (1999). Effects of repeated jugular puncture on plasma cortisol concentrations in loose-housed dairy cows. J Anim. Sci, 77(3), 708–714.
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Tomasello, M. (1999). The cultural origins of human cognition. Camebridge,MA.: Harvard University Press.
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Price, E. O. (1999). Behavioral development in animals undergoing domestication. App Anim Behav Sci, 65(3), 245–271.
Abstract: The process of domestication involves adaptation, usually to a captive environment. Domestication is attained by some combination of genetic changes occurring over generations and developmental mechanisms (e.g., physical maturation, learning) triggered by recurring environmental events or management practices in captivity that influence specific biological traits. The transition from free-living to captive status is often accompanied by changes in availability and/or accessibility of shelter, space, food and water, and by changes in predation and the social environment. These changes set the stage for the development of the domestic phenotype. Behavioral development in animals undergoing domestication is characterized by changes in the quantitative rather than qualitative nature of responses. The hypothesized loss of certain behavior patterns under domestication can usually be explained by the heightening of response thresholds. Increases in response frequency accompanying domestication can often be explained by atypical rates of exposure to certain forms of perceptual and locomotor stimulation. Genetic changes influencing the development of the domestic phenotype result from inbreeding, genetic drift, artificial selection, natural selection in captivity, and relaxed selection. Experiential contributions to the domestic phenotype include the presence or absence of key stimuli, changes in intraspecific aggressive interactions and interactions with humans. Man's role as a buffer between the animal and its environment is also believed to have an important effect on the development of the domestic phenotype. The domestication process has frequently reduced the sensitivity of animals to changes in their environment, perhaps the single-most important change accompanying domestication. It has also resulted in modified rates of behavioral and physical development. Interest in breeding animals in captivity for release in nature has flourished in recent decades. The capacity of domestic animals to survive and reproduce in nature may depend on the extent to which the gene pool of the population has been altered during the domestication process and flexibility in behavioral development. “Natural” gene pools should be protected when breeding wild animals in captivity for the purpose of reestablishing free-living natural populations. In some cases, captive-reared animals must be conditioned to live in nature prior to their release.
Keywords: Domestication; Domestic animals; Captivity; Behavioral development; Feral; Reintroduction
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Asa, C. S. (1999). Male reproductive success in free-ranging feral horses. Behavioral Ecology and Sociobiology, 47(1-2), 89–93.
Abstract: In the social organization of feral horses, adult males compete to monopolize groups or bands of females, sometimes called harems. Alternative male strategies are to remain alone or with other bachelors or, less commonly, to accept subordinate status within a harem. The hypothesis that dominant harem stallion status confers a reproductive advantage was tested in free-ranging feral horses. The presence of foals in harems headed by vasectomized (VSX) versus intact stallions was used to assess the ability of these stallions to control reproduction in their harems. Of harems headed by VSX stallions, 17 and 33% contained foals during years 2 and 3 post-treatment, respectively. In contrast, 86 and 80% of harems headed by non-VSX stallions contained foals in those years. Acquisition of pregnant mares appeared more likely than sneak copulations by bachelor stallions to account for foals in harems with a single stallion. However, most foals were born into harems that included a subordinate stallion, an occurrence that was undoubtedly exacerbated by the extended breeding season resulting from the sterility of the harem stallion. Thus, in comparing alternative reproductive tactics, bachelors appeared less successful than subordinate stallions within a harem. However, the highest reproductive success was achieved by the harem stallion, further demonstrating that alternative tactics are not equally profitable.
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