Aggressive Dominance Research Articles

Aggression and competition for shelter between a native and an introduced crayfish in Europe

1. The introduced North American crayfish, Pacifastacus leniusculus Dana, is expanding its range in Europe and locally often replaces two native crayfish species, Astacus astacus L. and Austropotamobius pallipes Lereboullet. Pacifastacus leniusculus is also expected to invade the habitat of a third native crayfish, the endangered Austropotamobius torrentium Schrank. Interspecific aggressive interactions and competition for shelter were experimentally studied in the laboratory to assess the potential impact of P. leniusculus on A. torrentium.2. Neither species was inherently dominant in aggressive interactions, but dominance was strongly size‐dependent, favouring the larger and faster growing species, P. leniusculus.3. Access to limited shelter was generally determined by aggressive dominance, although species‐specific preference also influenced the outcome of competition for shelter. Austropotamobius torrentium had a higher preference for experimental shelters and often defended these even against larger P. leniusculus.4. In accordance with theoretical models of animal conflicts, agonistic interactions between equally sized contestants were more severe than between animals of different size.5. The P. leniusculus used in the present experiment were infected with the crayfish plague, Aphanomyces astaci, to which the animals are resistant. The crayfish transmitted the disease to non‐resistant A. torrentium which died ≈ 2 weeks after contact with P. leniusculus.

EDITORIAL: GENETIC MODELS IN PHARMACOLOGY: PRESENT STATUS AND FUTURE

1.1. The classic animal models for human psychiatric conditions involves rodents As prey species, their normal behaviors of avoidance would be considered pathological in humans and dogs. Hence, such models may not be homologous for similar behaviors found in psychiatric pathology in humans.2.2. Dogs exhibit pathological behavioral conditions that may be equivalent to certain human psychiatric conditions. These canine conditions appear spontaneously or endogenously in the absence of genetic or neurochemcial manipulation, and as such, may be homologous to the human condition.3.3. If canine conditions approach homology with human conditions they should have excellent face, predictive, and construct validity.4.4. The canine conditions of separation anxiety, obsessive-compulsive disorder, cognitive dysfunction, dominance aggression, and panic disorder have good to excellent validity at all explored levels for human generalized anxiety disorder, obsessive-compulsive disorder, Alzheimer's disease, impulse control disorders, and panic disorder.5.5. Natural canine models can aid our understanding of human psychiatric conditions.

Sibling competition and the evolution of growth rates in birds

Variation among bird species in growth rates is traditionally attributed to differences in energy availability and developmental mode. However, the extent and form of competition among siblings for limited food resources may also be an important determinant. Kin-selection-based models of intrabrood competition suggest that nestling growth rates should be highest in those species in which siblings are likely to be less genetically related to one another (half-sibs rather than full-sibs). We test this novel prediction using the frequency of multiple paternity as an index of average sib relatedness within broods. As predicted, we find a significant positive association between the rate of multiple paternity within broods and nestling growth rates. Furthermore, this holds true when we control for the effects of variation in other factors that may be associated with variation in growth rate, such as body size, brood size, mating system and the form of parental care. We suggest, therefore, that variation in growth rate among bird species is not simply dependent on proximate ecological and developmental factors but is also strongly influenced by interactions, over an evolutionary time-scale, among kin.

An Experimental Study of Competition Between the Native Sacramento Perch (Archoplites interruptus) and Introduced Bluegill (Lepomis macrochirus)

The Sacramento perch (Archoplites interruptus), a sunfish (Centrarchidae) native only to the Central Valley of California, has been eliminated from most of its native range. To examine the role of interspecific competition in this decline, a series of experiments were conducted to assess the growth, aggressive behavior, and habitat use of Sacramento perch in the presence of bluegill (Lepomis macrochirus), an introduced centrarchid. The experiments indicate that (1) Sacramento perch gain less weight and show reduced growth when placed with bluegill, but that this interaction only occurs with food limitation, and is not affected by overall fish density; (2) Sacramento perch demonstrate less aggressive behavior than bluegill, but become more aggressive when they are conspicuously larger than bluegill; (3) Sacramento perch shift their habitat use in the presence of bluegill. Overall the results imply that Sacramento perch and bluegill exhibit interspecific competition where the mechanism of interaction is aggressive dominance by bluegill. It is suggested that long term persistence of Sacramento perch may require a habitat that is free of introduced centrarchid fishes, or one controlled by a naturally variable hydrological regime.

Behavioural changes in dogs with acral lick dermatitis during a 2 month extension phase of fluoxetine treatment

Acral lick dermatitis (ALD) is a condition described in dogs that is believed to be an animal model of obsessive–compulsive disorder (OCD) in humans. In both conditions, serotonergic neural dysfunction is believed to be responsible for aberrant grooming behaviour. ALD is the first animal model proposed for a psychiatric condition. Serotonergic antidepressants are recommended as first line treatment in OCD. However, many patients have been discouraged from using these by reports of aggression and suicide-inducing effects of these drugs. This study examined behavioural effects of a 2 month extension phase of fluoxetine treatment in dogs previously diagnosed with ALD. A 2 month extension phase on fluoxetine 20 mg daily, immediately followed on a 6 week double blind, randomised, placebo-controlled trial of fluoxetine in 63 dogs with ALD, diagnosed for at least 6 months. The Dodman scales measured excitability, fearfulness, dominance and territorial aggression at the start and end of the 2 month extension phase. Excitability was rated in four settings, referred to as questions 1 to 4. Fifty-four dogs completed the extension phase. Three subjects were withdrawn with no reason given, one for vomiting on fluoxetine. At the end of the extension phase, the analysis of variance showed no significant difference between dogs who received placebo or fluoxetine during the original trial, for scores of fearfulness (p=0·127), dominance (p=0·274) or territorial aggression (p=0·172). Excitability also caused no significant difference on the four questions (p1=0·822, p2=0·607, p3=0·975, p4=0·820). After the extension phase, owners assessed dogs as being neither more aggressive nor anxious. Particularly, there was no difference in levels of dominance aggression (p=1). Using the paired t-test there was no statistically significant difference between scores obtained both at the end of the 6 week trial and the extension phase for fearfulness (p=0·128), dominance aggression (p=1·0), territorial aggression (p=0·422) and excitability (p1=0·487, p2=0·571, p3=0·711, p4=0·086). These results may serve to refute further the reports of the emergence of impulsive aggression in human subjects on fluoxetine treatment as no significant behavioural changes were noted in the dogs treated with fluoxetine for ALD. © 1998 John Wiley & Sons, Ltd.

Threatened fishes of the world: Pimelodella kronei (Ribeiro, 1907) (Pimelodidae)

Common names: Bagre cego (Port.), blind catfish (E). Conservation status: Endangered (some populations), vulnerable (others). Identification: Troglobite (fish species restricted to a subterranean habitat). Differs from the epigean catfish Pimelodella transitoria as a result of the regression of the eyes and pigmentation, and slightly shorter dorsal spines. Degree of pigmentation variable, some individuals with vestigial eyes. D I + 6 (rarely I + 7), A 12–15 (most frequently 13–14), P I + 8–9 (rarely 10), V 6 (rarely 7) (Trajano & Britski 1993). Mean maximum size 15.4 cm SL. May consist of two or more cryptic species resulting from parallel evolution. Photograph by Ivan Sazima. Distribution: Karstic area in the region of Iporanga (24°35′ S, 48°35′ W, Upper Rio Ribeira Valley, south-east Brazil. Known from five limestone caves in the Parque Estadual Turistico de Alto Ribeiro (PETAR): Areias system (including the type locality, Areias de Cima), Bombas resurgence and Corrego Seco Cave on the right margin of the Betari River, tributary of the Ribeira River, and the Alambari de Cima and Gurutuva caves on the left margin of the Betari River. These two sets of caves are isolated because the Betari River flows along a non-soluble, diabase dyke. Since troglobites rarely disperse via surface waters, these demes may correspond to independent events of colonization followed by isolation and parallel evolution in the subterranean habitat (thus, distinct phylogenetic species). Habitat and ecology: Headwater streams in caves, with rocky beds and many rapids intercalated with soft-bottom pools. Food scarce, energy input largely allochthonous. Areias and, to lesser extent, Bombas populations have been studied in detail since 1983 (Trajano 1989, 1991b). Blind catfishes are generalist feeders and opportunistic carnivores, preying on invertebrates. Their cryptobiotic habitats are poorly developed, probably due to the absence of predators in the caves. These blind catfishes are active predators that frequently explore the water column and surface and do not exhibit photophobia (Trajano 1989); this behaviour makes them very vulnerable to capture. Between 1983 and 1985 the population of Areias Cave was estimated at 900–1200 blind catfishes, with a low density (0.04 individuals m in sites where P. kronei concentrates) (Trajano 1991a). At these sites the blind catfishes are sedentary and possibly territorial. Aggressive dominance is based primarily on size and, to a lesser extent, on prior residence (Trajano 1991b). A hierarchy is maintained through individual recognition, probably by olfactory communication. Life-history: Precocial life history with infrequent reproduction, slow individual growth rates (0.1 cm month) and increased longevity (10–15 years) (Trajano 1991a). Threats: Deforestation (affecting energy input) and habitat destruction are under control at present. Excessive media reports on the PETAR and on the blind catfishes (which are the symbol of the PETAR), plus inadequate control of visitation, are presently the main threats. Overcollection in the 1970’s and disturbance by tourists in some caves are the probable main causes of a visible population decline. Sewage pollution, including pollution from detergents (that may destroy the fish olfactory epithelium) is another problem in some caves. The Alambari de Cima Cave population was nearly extinct due to pollution from mining activities. As this deme probably comprises a separate, cryptic species, it should be considered as severely endangered. Conservation actions: Visiting Areias Cave without a scientific purpose was prohibited by the National Environmental Council through Regulation no. 5 passed on 6 June 1987, but this is a poorly enforced regulation. Conservation recommendations: Visitation by tourists to all P. kronei sites should be prohibited, along with the effective control of visitation and activities upstream of the cave system (e.g. mining and deforestation). A reduction in media coverage would deflect public attention from blind catfishes and probably reduce clandestine visitation and catching; P. kronei localities should therefore not be widely publicised. Remarks: Troglobites in general are vulnerable to environmental stresses due to habitat restriction, reduced geographical distribution, relatively low tolerances of environmental fluctuations, small populations and precocial life histories, which make the recovery of declining populations a slow process. Several other Brazilian trogobitic fishes, which are poorly known, should also be considered to be potentially threatened.

Owner attitudes and dog behaviour problems

In the treatment of dog behaviour problems, assessment of the owner's attitude is usually an essential part of the diagnostic process. Questionnaire studies of groups of owners reveal wide variation in both degree and kind of owner attachment. Individual-centred methods such as the Kelly Repertory Grid demonstrate the complexity of such attachments. It is suggested that the psychoanalytic concept of projection can often best explain their irrational aspects: experimental evidence is adduced and clinical examples discussed. With regard to particular types of behaviour problems, there is evidence of an association between dominance aggression in the dog and the anthropomorphic involvement of the owner; also between over-excitement and displacement activities in the dog and anxiety in the owner. Owner anxiety is not associated with a higher incidence of phobias in the dog; a dog's phobia, however, does tend to cause greater distress to a more anxious owner.

Age, testosterone, and behavior among female prison inmates.

The objective of the study was to determine how testosterone levels, both alone and interacting with age, were associated with criminal behavior and institutional behavior among female prison inmates. Subjects were 87 female inmates in a maximum security state prison. Criminal behavior was scored from court records. Institutional behavior was scored from prison records and interviews with staff members. Testoster-one levels were scored from radioimmunoassay of saliva samples. Product-moment correlations revealed first-order relationships among age, testosterone, criminal behavior, and institutional behavior. Structural equation analysis suggested a causal model in which age leads to lower testosterone, which in turn leads to less violent crime and less aggressive dominance in prison. Testosterone is related to criminal violence and aggressive dominance in prison among women, as has been reported among men. Changes in these behaviors with age are in part explained by a decline in testosterone levels.

Characterization and treatment of 20 canine dominance aggression cases.

This study was undertaken to characterize 20 cases of dominance aggression seen at Tufts University School of Veterinary Medicine and to investigate the efficacy of our non-confrontational behavior modification program for 8 weeks. The 20 cases included 18 pure breed and 2 mixed breed dogs. Thirteen of the dogs were male. The dogs' ages ranged from 7 to 84 months (mean 32.1 +/- 22.64 SE). There was no correlation between the severity of dominance aggression and the signalment of the dogs. At the conclusion of the eight week follow up period, 14 dogs (70%) were reported to have responded to the treatment to some degree. Six dogs did not demonstrate any noticeable reduction in aggressive behavior or became more aggressive. The results of the study is powerful evidence of the efficacy of the non-confrontational behavior modification program.

Use of fluoxetine to treat dominance aggression in dogs

Objective To evaluate fluoxetine for the treatment of owner-directed dominance aggression in dogs. Design Prospective study. Animals 9 dogs of various breeds, ages, and either sex determined to have owner-directed dominance aggression. Procedure Placebo and fluoxetine (1 mg/kg of body weight) were compared for the treatment of owner-directed dominance aggression in a single-blind crossover study. Owners were instructed to record aggressive and nonaggressive responses of their dogs daily on a canine-overt aggression chart for the 5-week duration of the study. Total aggression scores (linear and geometric) were calculated for each week of the study. The frequency of individual responses was also analyzed independently. Results Fluoxetine resulted in a significant (P = 0.01) reduction in owner-directed dominance aggression after 3 weeks of treatment. No particular aggressive response accounted for the overall reduction in aggression. Clinical Implications Fluoxetine may be useful in the management of dominance aggression in dogs. (J Am Vet Med Assoc 1996;209:1585–1587)

Dominance aggression of a dog towards one member of a family

Dominance aggression of a dog towards one member of a family

Influence of owner personality type on expression and treatment outcome of dominance aggression in dogs

Objective To determine the success rate of positive training methods and behavioral modification techniques in dogs with dominance aggression and to compare personality profiles between owners of dominant-aggressive and nondominant dogs. Design Prospective clinical study. Animals 10 dominant-aggressive dogs and 10 nondominant, nonaggressive control dogs. Procedure Dominance aggression was quantified, using an aggression score, in the 10 dominant dogs before and after a nonconfrontational behavior modification program. The personality profile of the owners of dominant and control dogs, assessed by means of a Keirsey temperament sorter, was compared, as was the influence of owner personality on the outcome of behavioral modification in the dominant dogs. Results 9 of 10 dominant dogs responded to the nonconfrontational treatment program by a decrease in aggressive response to similar eliciting stimuli. Significant differences were not found between the personality of the owners of dominant versus control dogs, and owner personality did not significantly affect the outcome of behavior modification treatment. Clinical Implications Nonconfrontational behavior modification programs are effective in reducing owner-directed dominance aggression in dogs, Owner personality does not necessarily predispose certain individuals to assaults by dominant dogs or profoundly affect their ability to engage in a successful behavioral modification program. (J Am Vet Med Assoc 1996; 209:1107-1109)

Dominance relationship in the establishment of reproductive division of labour in a primitively eusocial wasp ( Ropalidia marginata )

In mature post-emergence colonies of the tropical primitively eusocial polistine wasp Ropalidia marginata, the queen is not a behaviourally dominant individual. Nevertheless, she completely suppresses reproduction by the workers and becomes the sole egg-layer in the colony. Mechanisms by which a female is able to establish her exclusive reproductive status in the colony can be investigated by examining dominance-submission relationships and hierarchy formation at particular stages of the colony cycle when reproductive competition is behaviourally manifest. Observations on the behaviour of R. marginata females (1) during early stages of colony-founding, (2) when potential queens challenge the existing queen, and (3) immediately after queen replacement show that these wasps use highly aggressive dominance interactions to establish their reproductive status. Both the frequency and the intensity of dominance behaviours are significantly higher at these stages than those observed at phases of the colony when there is no apparent reproductive strife. Once her position as the only egg-layer of the colony has been established, the levels of dominance interactions initiated by the queen decrease and the nature of these interactions also becomes comparatively milder. Thus, the mechanisms by which a queen establishes her social status in her colony and those by which she continues to suppress reproduction of her nestmates in the absence of overt physical dominance may be quite different.

Behavioral Interference for Perch Sites in Two Species of Introduced House Geckos

Behavioral Interference for Perch Sites in Two Species of Introduced House Geckos

Effect of dietary protein content on behavior in dogs

Objective— To determine the effect that feeding diets containing a low (17%), medium (25%), or high (32%) protein content would have on behavior in dogs. Design— Prospective, controlled study. Animals— 12 dogs with dominance aggression, 12 dogs with hyperactivity, 12 dogs with territorial aggression, and 14 control dogs without behavioral problems. Procedure— Dogs were fed each of the diets for a 2-week period, and owners were instructed to score their dogs' behavior on a daily basis. Results— Behavior of the dogs with dominance aggression, dogs with hyperactivity, and control dogs was unchanged by the dietary manipulations. Territorial aggression was significantly reduced when dogs were fed the low- or medium-protein diet, compared with territorial aggression when fed the high-protein diet. Post hoc analysis indicated that this effect was attributable to a marked reduction in aggression in a subset of the group (n = 7) in which territorial aggression was a result of fear. Clinical Implications— Results of this study suggest that a reduction in dietary protein content is not generally useful in the treatment of behavior problems in dogs, but may be appropriate in dogs with territorial aggression that is a result of fear. (J Am Vet Med Assoc 1996;208:376-379)

Primate cognition and the bared-teeth display: a reevaluation of the concept of formal dominance.

The cognitive implications of the phenomenon of dominance in nonhuman primates and other animals have been poorly addressed. This article shows that the concept of formal dominance currently used in the primatological literature is inherently dependent on the assumption that primates are capable of attribution of knowledge to other individuals. Although this assumption has never been made explicitly, without it the concept of formal dominance is virtually indistinguishable from other, more traditional views of dominance. Recent studies have failed to demonstrate attribution of knowledge in nonhuman primates, thus questioning the validity of formal dominance. The concept of formal dominance was originally proposed to account for a discrepancy between dominance hierarchies based on aggressive behavior and dominance hierarchies based on submissive signals. This article shows that such a discrepancy can be accounted for without invoking complex cognitive processes such as attribution of knowledge.

The evolutionary significance and social perception of male pattern baldness and facial hair

Both male facial hair and male pattern baldness are genetically based, suggesting that they contributed to fitness. The multiple fitness model provides an evolutionary interpretation of the social perception of male pattern baldness and beardedness in terms of the multidimensional meaning of physical maturational stages. Male facial beardedness is associated with the sexual maturation stage and is hypothesized to signal aggressive dominance. Male pattern baldness, by contrast, is associated with the next stage of physical maturation, termed senescence. Pattern baldness may signal social maturity, a non-threatening form of dominance associated with wisdom and nurturance. We tested these hypotheses on social perceptions using manipulated male facial stimuli. We presented faces with three levels of cranial hair, including full, receding, and bald, and two levels of facial hair, beard with moustache and clean shaven. Consistent with the model, a decrease in the amount of cranial hair was associated with increased perceptions of social maturity, appeasement, and age, and decreased perceptions of attractiveness and aggressiveness. Targets with facial hair were perceived as more aggressive, less appeasing, less attractive, older, and lower on social maturity than clean shaven faces.

Behavior problems of companion birds

Many owners of companion psittacine birds complain of behavior problems. The large size and considerable intelligence of these pets can lead to daunting problems. Common complaints include aggression towards the owner, screaming, overdependence, and feather-picking. Causes, prevention and treatment of these problems were addressed. Pet bird husbandry and management were also discussed. Training the agility dog Amy R. Marder Angel1 Memorial Animal Hospital, Boston, MA 02130, USA Abstract Agility training can be helpful within a behavior modification program. Agility is easy and fun for both owners and dogs. Owners see positive results quickly, and readily learn behavior modification techniques within the framework of an agility class. Training is done with positive reinforcement alone, using food or toys. Such training has been used successfully in dogs which are afraid of people and other dogs, and in cases of dominance aggression.

Serotonergic control of androgen-induced dominance

The present study investigates the role of serotonergic systems in anabolic steroid-induced aggression. An animal model of aggressive dominance was used to assess the chronic effects of testosterone propionate. When rats that had become dominant following administration of testosterone propionate received serotonergic agonists with selectivity for the 5-HT 1A receptor (8-OH-DPAT, buspirone, gepirone), the 5-H 1B receptor (eltoprazine, TFMPP), or the 5- HT 2A 2C receptor (DOM), a dose-dependent decrease in dominance was demonstrated. Pretreatment with three serotonergic antagonists (pizotyline, pirenpirone, and pindolol) blocked agonist-induced reductions in dominance in varying degrees. Nonserotonergic agonists with CNS depressant effects were also tested in dominant animals. The benzodiazepine, chlordiazepoxide, did not reduce dominance except at doses that interfered with motor behavior. The opioid agonist, morphine, dose dependently decreased dominance, but this effect was reversible with administration of the serotonergic antagonist, pirenpirone, suggesting the antidominant effect of morphine had a serotonergic component. Biochemical experiments demonstrated that following chronic testosterone propionate, there was a decrease in levels of 5-HT and 5-HIAA in the hippocampus but not in the striatum or the frontal cortex. Chronic testosterone propionate also caused an increase in the affinity of [ 3H]8-OH-DPAT for the 5-HT 1A receptor but no corresponding change in the density of 5-HT 1A binding sites in the hippocampus. There was also no change in the properties of the 5-HT 2 receptor in the frontal cortex following chronic testosterone propionate. These data suggest that serotonergic systems may play an important role in the control of anabolic steroid-induced aggressive dominance.

Aggressive competition for critical resources among migratory birds in the Neotropics

SummaryCompetition between closely related species of migratory birds is thought to be important in determining their winter distributions, habitat and resource use. However, the role of active dominance interactions has generally been downplayed. In this paper we review the occurrence of interspecific feeding territories among certain Neotropical migrants. Aggressive dominants have been reported primarily at flowering plants, but also at the honeydew from scale insect infestations, the canopy of insect-rich pioneer trees and, occasionally, fruiting trees. Although the phenomenon is uncommon, aggressively dominant species may be important in certain habitats. The presence of such interspecific territorial systems argues for the poverty of resources in the habitat as a whole. Studying aggressive interactions among migrants is a way of using bird behaviour to define critical resources for conservation management.