Deferred agonistic behavior in a long-lived scincid lizard Eumeces laticeps

Summary A laboratory experiment with the broad-headed skink (Eumeces laticeps) involving staged agonistic encounters demonstrates that larger males have an advantage over smaller ones in agonistic bouts. Field data on head wounds produced by intraspecific fighting during the breeding season show a much higher frequency of new wounds among males over 100 mm in snout-vent-length than in smaller males. The significant difference in new-wound frequency strongly suggests avoidance of fights by the small males, which is corroborated by laboratory and field observations. Access by males to reproductively active females depends on the ability to defeat other males in aggressive contests virtually always involving head biting if the males are of nearly equal size. Because the probability of winning agonistic encounters increases with size, young males avoid fights with older males. Aggressive contests with larger males and reproductive attempts other than courtship in the absence of larger males are deferred.Aggressive behavior in E. laticeps may be employed in direct defense of females, but might also be expressed in defense of specific sites and/or territories. In the laboratory, males in their home cages were significantly more likely to win encounters with males of similar size than were males fighting in the home cages of opponents. This suggests that encounter site could be important in determining encounter outcome and that field study of possible site defense or territoriality is needed.     

Effect of testosterone and melatonin on social dominance and agonistic behavior in male Tscheskia triton

Social dominance and agonistic behavior play important roles in animal societies. Melatonin and testosterone are closely related to social dominance and agonistic behavior in rodents, but interactions between both of them remain unknown. In this study we investigated the effects of testosterone and melatonin by manipulating photoperiod and castration on social dominance and agonistic behavior in male Tscheskia triton. Castration significantly decreases social dominance of both short- and long-day males, suggesting that testosterone benefits social dominance of males in both breeding and non-breeding seasons. In intact conditions, long-day males tended to dominate short-day males, suggesting that the effect of testosterone on social dominance was a little stronger than melatonin. However, castrated short-day males became dominant over their castrated long-day opponents meaning that high melatonin levels obviously benefit social dominance in males. Hormone implantation indicated that testosterone had no effect on non-breeding condition, but that melatonin was important during the breeding season. Our results indicate that both testosterone and melatonin are important in determining social dominance in male hamsters, and the effect of testosterone appears to be stronger than melatonin. Testosterone is responsible for aggression and social dominance in male hamsters during the breeding season, while melatonin regulates behavior during non-breeding, probably due to the different seasonal secretory patterns of the hormones.     

雄性大仓鼠体重对其斗殴行为及社会等级的作用

在实验室条件下测定雄性大仓鼠体重对社会等级和斗殴行为的作用模式,检验体重对雄性大仓鼠社会等级及斗殴行为序列具有重要影响的假设。本实验以16只成年雄性大仓鼠为目标个体,采用等级内部的线性概率、组内循环三元组数量（d）和优势等级的线性度（K）,排列个体的社会等级序位。研究结果表明,雄性大仓鼠可形成近似线性的优势等级,体重与个体的优势等级,攻击行为和胁腺标记行为均呈显著的正相关关系,与防御行为和攻击潜伏期存在显著的负相关关系。说明独居性物种大仓鼠雄体间可形成优势等级关系,体重对此关系具有重要的作用。     

Imaging emotional brain functions: Conceptual and methodological issues

This article reviews the psychophysiological and brain imaging literature on emotional brain function from a methodological point of view. The difficulties in defining, operationalising and measuring emotional activation and, in particular, aversive learning will be considered. Emotion is a response of the organism during an episode of major significance and involves physiological activation, motivational, perceptual, evaluative and learning processes, motor expression, action tendencies and monitoring/subjective feelings. Despite the advances in assessing the physiological correlates of emotional perception and learning processes, a critical appraisal shows that functional neuroimaging approaches encounter methodological difficulties regarding measurement precision (e.g., response scaling and reproducibility) and validity (e.g., response specificity, generalisation to other paradigms, subjects or settings). Since emotional processes are not only the result of localised but also of widely distributed activation, a more representative model of assessment is needed that systematically relates the hierarchy of high- and low-level emotion constructs with the corresponding patterns of activity and functional connectivity of the brain.     

Conceptual and methodological issues in the comparative study of collective group movements

In our commentary, we highlight several conceptual and methodological problems that have hampered broader integration of studies of collective group movements. Specifically, we argue that studies of captive animals should only be used to elucidate behavioural mechanisms. Moreover, the diversity of physical environments in which group movements occur as well as the social diversity of groups deserve more consideration in integrative studies. Furthermore, tests of predictions based on modelling studies are often hampered by the fact that models include variables that are difficult or impossible to measure in real animals. We also advocate the use of an empirical, rather than subjective establishment of operational definitions of group movements and the associated individual roles. Finally, we emphasize the utility of controlled experiments in the study of collective decision-making and group movements and encourage their wider application.     

Genetics-squared: combining host and pathogen genetics in the analysis of innate immunity and bacterial virulence

The interaction of bacterial pathogens with their hosts’ innate immune systems can be extremely complex and is often difficult to disentangle experimentally. Using mouse models of bacterial infections, several laboratories have successfully applied genetic approaches to identify novel host genes required for innate immune defense. In addition, a variety of creative bacterial genetic schemes have been developed to identify key bacterial genes involved in triggering or evading host immunity. In cases where both the host and pathogen are amenable to genetic manipulation, a combination of host and pathogen genetic approaches can be used. Focusing on bacterial infections of mice, this review summarizes the benefits and limitations of applying genetic analysis to the study of host–pathogen interactions. In particular, we consider how prokaryotic and eukaryotic genetic strategies can be combined, or “squared,” to yield new insights in host–pathogen biology.     

Effects of group composition on agonistic behavior of captive pigtail macaques,Macaca nemestrina

We surveyed agonistic behaviors of 20 captive groups of pigtail macaques (Macaca nemestrina) housed under identical spatial conditions. Fifteen groups contained one male each; the other five groups contained no adult males. Groups included six to twelve adult females, some of which had infants with them. We found no relationship between social density of groups and incidence of agonistic behavior, but significantly more contact aggression (grab, hit, push, bite) and noncontact aggression (chase, open-mouth “threat,” bark vocalization) occurred among females in groups containing no males than in those containing one male each. Apparently, males played an important role in the inhibition of intragroup conflict. We also found that females in groups containing males exhibited less noncontact aggression if infants were present than if no infants resided in their groups. Thus, competition of females over infants must not have been an important constituent of intragroup conflict under the conditions of this survey.     

Large scale ENU screens in the mouse: genetics meets genomics

The worldwide effort to completely sequence the human and mouse genome will be accomplished within the next years. The focus of current activities within the framework of human genome research is mainly on the assembly of high resolution genetic and physical maps and genomic sequencing. Cloning of new genes is getting more easy using those maps. Nevertheless, it is necessary to work on a systematic analysis of gene function. Results obtained from these efforts will be of enormous value for future biological and biomedical research. However, even the complete sequence will not in all cases reveal the molecular and cellular role of the different genes. Therefore, the next phase of the Human Genome Project will have at its core the functional analysis of genes. Those genes relevant for the diagnosis, prevention and therapy of human diseases are of particular interest. Looking at the history of life sciences, mutants have been the most important tool to obtain insight into the biological function of genes. The mouse is the model of choice for the study of inherited diseases in man. In order to meet the requirements for functional human genome analysis, we need a large number of mouse mutants similar to the collection of mutants available for other model organisms such as flys and worms. To fully apply the power of genetics, multiple alleles of the same gene such as hypomorphs or hypermorphs are required. Efficient production of mouse mutants showing specific phenotypes can be achieved by the use of ethylnitrosourea (ENU). ENU is the most powerful mutagen known and we currently see a renaissance of ENU mutagenesis. The application of ENU mutagenesis is reviewed and discussed in the context of a new era of functional genomics.     

Seasonal changes in territoriality and frequency of agonistic behavior in two densities of juvenile brown bullhead,Ictalurus nebulosus

Synopsis Incidence of territoriality and frequency of six agonistic action patterns of juvenile brown bullhead, Ictalurus nebulosus, were observed in the laboratory over a two year period at two fish densities under conditions of constant light and temperature. High density fish showed little territoriality or agonistic behavior while low density fish displayed an annual cycle of agonistic behavior and territoriality. Agonistic behavior frequency and incidence of territoriality peaked in February and March and were higher the second year when compared with the first.     

Conceptual,methodological and ethical issues in genetic engineering (1989)

An introduction to the potential of gene therapy to alleviate illness and death particularly for many rare human genetic disorders and specific forms of cancer is presented. At present, genetic engineering, that is gene therapy to correct some of these disorders based on new molecular biology procedures is a possibility in the near future especially those with single gene mendelian inherited transmission. After a short, comprehensive overview about the molecular biology of genetic engineering, a presentation of many of the ethical issues now under discussion by the international scientific community, world govenmental agencies and concerned laymen about the complex and sensitive ethical issues is provided. A report about a case history of investigators in the United States who disregarded current restrictions emphasized the concern of the scientific community as well as the governmental agencies in maintaining stepwise, careful approach to the introduction of the new, molecular methodologies. The continued maintenance of many of these restrictions, suggested by some ethicists, even after the threat of uncontrolled biological disorder as a result of these new procedures was found to be erroneous is discussed and challenged.     

Behavioural determinants of agonistic success in invasive crayfish

Ecosystems today increasingly suffer invasions by multiple invasive species, some of which may share similar advantageous life history traits and ecological niche. In such cases, direct competition can influence invasion success of both species, and provide insights into competition without co-evolution in species equally novel to the environment. We used two widespread crayfish invaders of freshwater ecosystems of Europe, signal crayfish (Pacifastacus leniusculus) and spiny cheek crayfish (Orconectes limosus), to investigate how behavioural decisions in agonistic encounters contribute to competitive advantages in the absence of adaptation to either opponents or an environment. In direct competition against novel but comparable opponents, the key factor for establishing clear dominance of P. leniusculus in interspecific bouts was its greater tendency towards continued engagement in high-intensity fights. With O. limosus individuals consistently retreating from staged bouts as fights became more intense, P. leniusculus individuals did not need to adapt their strategy to be successful, suggesting that their agonistic behaviour intrinsically predisposed them to win. While both species are detrimental to invaded ecosystems, our results indicate that aggressive behaviour of P. leniusculus against unfamiliar opponents could allow it to more easily outcompete other comparable species and consequently present a potentially greater threat for native ecosystems.     

Neonatal exposure to estradiol decreases hypothalamic allopregnanolone concentrations and alters agonistic and sexual but not affective behavior in adult female rats

Exposure of developing female rats to estradiol during the perinatal period induced long-lasting dysregulation of gonadal axis and decreased cerebrocortical and plasma concentrations of allopregnanolone. We have now examined the effects of neonatal estradiol administration in female rats on hypothalamic allopregnanolone concentrations and on exploratory, affective, agonistic and sexual behaviors as well as social learning. A single administration of β-estradiol 3-benzoate (EB, 10 μg) on the day of birth resulted in a delay of vaginal opening, acyclicity and ovarian failure. These alterations were associated with a significant decrease in the concentrations of allopregnanolone in the hypothalamus at 21 and 60 days, but not at 7 days, after birth. Neonatal administration of EB also increased agonistic behaviors in adult rats, such as dominant behaviors and following of an ovariectomized intruder, while living attacks unaffected. EB-treated rats showed also an increase in anogenital investigation, associated with a drastic reduction in spontaneous and induced female sexual behaviors (receptivity and proceptivity). In contrast, neonatal administration of EB did not affect locomotor activity, anxiety- and mood-related behaviors, the social transmission of flavor preferences, and seizures sensitivity. These effects of estradiol suggest that it plays a major role in regulation of both the abundance of allopregnanolone and the expression of agonistic and sexual behaviors, while failing to influence affective behaviors and social learning. Thus, the pronounced and persistent decrease in hypothalamic allopregnanolone concentration may be related to the manifestation of agonistic and sexual behaviors.     

普氏野马繁殖群在组建和放归初期的争斗行为与社群等级建立

2007年5月下旬至6月下旬,针对新组群并放归于卡拉麦里有蹄类保护区第二放归点的普氏野马(Equus przewalskii)繁殖群,采用焦点动物取样法和全事件记录法,观测记录了组群和放归初期繁殖群内个体间的争斗行为(攻击行为和屈服行为),以优势指数法确定繁殖群内的个体等级序列。结果表明,新组群内个体的年龄与攻击行为发出次数不存在显著的相关性(r=0.60,t=1.62,rr0.05),攻击与屈服行为次数也无显著的相关性(r=0.56,t=1.41,rr0.05)。各个体之间从最初组群到野放争斗行为日趋减少,社群等级逐渐建立并趋于稳定。     

Serotonin and octopamine elicit stereotypical agonistic behaviors in the squat lobster Munida quadrispina (Anomura, Galatheidae)

Serotonin and octopamine have been implicated as modulators of posture and behavior in several crustaceans. Here we characterize the agonistic behaviors of normally interacting squat lobsters Munida quadrispina (Anomura, Galatheidae) and their responses to serotonin and octopamine injected into the ventral hemolymph sinus, in order to evaluate the potential roles of these amines in modulating agonistic behaviors. Normally interacting M. quadrispina do not develop lasting dominance hierarchies, although transient aggressive and submissive displays do occur. Injected serotonin elicits postures and behaviors in isolated individuals similar to those typical of aggressive, normally interacting animals. Injected octopamine can produce postures and behaviors typical of submissive animals, and elicits behaviors which imply a modulatory role for octopamine in tailflipping. The effects of both amines are reversible and dose dependent, and the dose-response curves parallel the normal progression of agonistic interactions. The social behaviors and reactions to injected serotonin and octopamine of M. quadrispina differ from those of lobsters and crayfish, indicating that interspecific differences in neuromodulation of behavior and motor output exist. Such differences have implications for the understanding of aminergic modulation of aggression and the evolution of aminergic modulation in crustaceans. Accepted: 22 June 1997     

Harnessing the mouse to unravel the genetics of human disease

Complex traits, i.e. those with multiple genetic and environmental determinants, represent the greatest challenge for genetic analysis, largely due to the difficulty of isolating the effects of any one gene amid the noise of other genetic and environmental influences. Methods exist for detecting and mapping the Quantitative Trait Loci (QTLs) that influence complex traits. However, once mapped, gene identification commonly involves reduction of focus to single candidate genes or isolated chromosomal regions. To reach the next level in unraveling the genetics of human disease will require moving beyond the focus on one gene at a time, to explorations of pleiotropism, epistasis and environment-dependency of genetic effects. Genetic interactions and unique environmental features must be as carefully scrutinized as are single gene effects. No one genetic approach is likely to possess all the necessary features for comprehensive analysis of a complex disease. Rather, the entire arsenal of behavioral genomic and other approaches will be needed, such as random mutagenesis, QTL analyses, transgenic and knockout models, viral mediated gene transfer, pharmacological analyses, gene expression assays, antisense approaches and importantly, revitalization of classical genetic methods. In our view, classical breeding designs are currently underutilized, and will shorten the distance to the target of understanding the complex genetic and environmental interactions associated with disease. We assert that unique combinations of classical approaches with current behavioral and molecular genomic approaches will more rapidly advance the field.     

Agonism,ranking, and the social behavior of adult male baboons

An ingrained technique in primatological analysis is to rank individual animals in a hierarchical system that is usually but not always based on the outcome of agonistic encounters. An explication of group structre and function is then sought by correlation these rankings with aspects of behavior. When the behavior of the adult males in a free-ranging troop of olive baboons is examined, ranking is found to be inadequate to represent the behavioral variability existing between individuals. The relationships maintained by these animals is analyzed, emphasizing amounts of time devoted to specific activities, and it is recommended that affiliative rather than agonistic behavior be stressed in future studies.     

Effect of emotionality, exploratory activity and pain sensitivity on manifestation of agonistic behavior in the mouse

Mice of C57BL/6J line with higher exploratory and motor activities and with lower emotionality and pain threshold recorded in standard tests, as compared with the animals of CBA/Lac line, have also been found to manifest a more expressed aggression in their intermale contacts in reaction to a syngeneous partner. It is suggested that the studied physiological and behavioural parameters may determine in considerable degree the character of aggressive and submissive mice behaviour in an agonistic interaction.     

Social behavior of the emperor tamarin in captivity: Components of agonistic display and the agonistic network

Agonistic behavior was studied longitudinally for 16 months in an intact family groups of captive emperor tamarins (Saguinus imperator subgrisescens) using methods from quantitative ethology and social network analysis. A motivational analysis of the components of agonistic display revealed the relative strength of each component along a continuum from strongly dominant to strongly subordinate. Tabulations of exchanges of strongly dominant and strongly subordinate components in interactions among the tamarins revealed an agonistic network (“dominance hierarchy”) that approached, but did not quite reach, the ideal state of a transitive order (“linear dominance hierarchy”). The frequency with which individual tamarins long called and scent marked was not closely correlated with their position (“dominance rank”) in the agonistic network. Instead, individuals undergoing change in status long called and scent marked frequently, irrespective of their rank.