Animal agonistic behaviors, including threat, combat, submission and chase, are complex responses to experimental stimuli. Animal behaviors are regulated by the central nervous system. In the central nervous system, the biogenic amine serotonin has been thought to serve important roles in animal aggression (including fish), but it¡¦s not clear if serotonin affects threatening and fighting differently. This study took experimental approaches to examine the effects of this neurotransmitter on threatening and fighting in a paradise-fish model in which the complex agonistic behavior is well characterized. Treatments with serotonin synthesis precursor tryptophan (0.125mg/g) to one of the two contestants had insignificant effects on threatening or fighting while synthesis blocker p-Chlorophenylalanine (PCPA) (0.3mg/g) decreased threatening time and occurrences of head-tail display. When these drugs were added to both contestants, tryptophan reduced all agonistic behavioral patterns displays, and PCPA decreased threatening time and head-tail display. In addition to changes in behavioral patterns, tryptophan led the fish to be attacked. In contrast, PCPA led the injected fish to actively attack its opponent. However, tryptophan and PCPA had no effect on social status in parasise fish. I suggest that agonistic responses and the initial fighting decision in a paradise fish are affected not only by level of its serotonin, but also by the behavioral responses of its opponent. And the establishment of outcome of encounter is affected more by the environmental stimuli than the serotonin level.

In male golden hamsters, puberty is marked by dramatic changes in agonistic behavior. Attack frequency gradually decreases as agonistic behavior evolves from play fighting to adult aggression. Attack types change as targets of attack mature from play fighting to adult attacks. In adult hamsters, serotonin plays an inhibitory role in aggression. Thus, the decline in attack frequency during puberty could be associated with an up-regulation of the activity of the serotonergic system. In adults, acute Fluoxetine treatment inhibited aggressive behavior at all doses. In juveniles, only the highest dose reduced attack frequency. Interestingly, juveniles treated with the lowest dose showed an increase in aggressive behavior. Attack type was also affected as treatment with Fluoxetine accelerated the maturation of attack targets. This same effect had been observed in previous studies in response to chronic social stress and dexamethasone treatment. Consequently, the role of cortisol on the development of the serotonergic system was also investigated. Furthermore, the density of serotonin innervation in the anterior hypothalamus and medial amygdala was found to be higher in adults than juveniles and consistent with the inhibition of attacks by the high dose of Fluoxetine. However, the differential effects of Fluoxetine at the lower doses were investigated through analysis of different serotonin receptor subtypes. In adult hamsters, aggression can be facilitated by activation of 5-HT₃ receptors and inhibited by 5-HT[subscript 1A] receptors. During puberty, the density of immunoreactive 5-HT1A receptors increased in the anterior hypothalamus and medial amydala while 5-HT₃ receptor immunoreactivity did not change. Thus, it is possible that in these areas the ratio of 5-HT₃ to 5-HT[subscript 1A] receptors decreases during puberty. This change is consistent with the decline in the frequency of offensive responses during puberty. The functionality of 5-HT[subscript 1A] and 5-HT₃ receptors on offensive aggression in juveniles was tested via peripheral injections of a 5-HT[subscript 1A] receptor agonist and a 5-HT₃ receptors antagonist. At the high dose, both drug treatments inhibited attack frequency and attack repetition. Together, these data examine the role of the serotonergic system on the development of agonistic behavior. / text

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

No description available.

Thesis advisor: David Krauss / Behavior in a confined group of mandrills (Mandrillus sphinx) and a confined group of ring tailed lemurs (Lemur catta) were analyzed to reveal any significant differences in agonistic behaviors and to assess the varying stress levels between individuals. I predicted that the activity rate of the individuals would determine the amount of agonistic behavior demonstrated, specifically that more active individuals would be more frequently performing agonistic behaviors than those who were less active. The mandrills as a whole exhibited a higher activity rate than the lemurs, and the proportion of time spent exhibiting agonistic behaviors was also higher, as expected. These results suggest that the mandrill population is under more stress than the lemurs. Differences in the age makeup of these groups may partially explain the behavioral differences that occurred: the mandrills' group included a juvenile who was considerably more active than his parents while all three lemurs observed were adults. Differences in the size of the exhibit may also explain the differences as the exhibit for the mandrills was smaller than that of the lemurs, while the mandrills were more than triple the lemurs' size. This analysis supports earlier studies: that primate behavior is influenced strongly by their environment and its cohabitants. / Thesis (BS) — Boston College, 2004. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Biology. / Discipline: College Honors Program.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Includes bibliographic references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Coexistence among ecologically similar species is often facilitated through temporal or spatial partitioning mechanisms that reduce or eliminate direct interaction. However, in many communities exhibiting guild structure, wherein potential competitors may also prey on one another, sympatric relationships persist despite species' similar life history strategies, spatial and temporal restrictions imposed by ephemeral habitats, and resource limitations that promote competition and predation. To identify the ecological roles of species-specific behavioral patterns within aquatic guilds, I quantified larval intraspecific agonistic behavior among two species of intraguild (IG) predators, Ambystoma opacum and A. tigrinum, and their shared intraguild prey, A. maculatum. All species exhibited similar ontogenetic patterns of aggression, characterized by peaks of aggression early in development and subsequent gradual decreases through metamorphosis. However, the intensity of aggression varied considerably among guild species through development, as did behavioral responses to varying levels of ambient water temperature, invertebrate prey density, and presence of predatory odonate naiads. The observed patterns suggest that guild species, despite morphological and physiological similarities, exhibit unique behavioral responses through ontogeny and in response to habitat variables, suggesting that temporally staggered breeding phenologies have contributed to behavioral divergence among these sympatric congeners. However, in situ observations of larval behavior, although largely in agreement with laboratory results on timing of increased aggression, indicated that IG predators exhibited pond-level species partitioning and do not necessarily co-occur despite being regarded as sympatric. These results, taken together with observed species-specific impacts of IG predators on IG prey, suggest that ecologically similar IG predators exert widely differing predatory pressure on shared prey, and that similarities among guild species may ultimately result in habitat partitioning across local scales.

Agonistic behavior and dominance are described for captive Townsend's chipmunks (Eutamias townsendii). A total of 10,739 encounters was recorded; 644l (59.9%) were agonistic. Chases (58.5%) and displacements (30.8%) were the predominant agonistic behaviors; threats (6.8%) and fights (4.l%) were relatively rare. Stable, non-triangular hierarchies were rapidly established in 11 of the 12 groups of chipmunks observed; the presence of individuals of equal rank in some groups precluded strict linearity. Dominance positions did not change within a group, but reversals in rank and changes from equal to dominant-subordinate reltionships occurred when the mebership of groups was changed. One hierarchy existed for both sexes; neither sex was consistently dominant. Experience and individual differences in activity and aggresiveness were more important determinants of an animal's position than were sex or size. No correlation was found between rank and encounter frequency, nor was closeness of rank strongly correlated with high numbers of agonistic encounters between any two chipmunks. The frequencies of recognitory and sexual behavior were inversely related to the frequency of agonistic behavior between the pairs of animals. Ritualized throats and appeasement behaviors did not replace overt aggression in established hierarchies. Members of hierarchies showed neither a reduction in numbers of asonistic encounters, nor temporal changes in froquency of the different types of agonistic behavior. Agonistic encounters increased in frequency from August to December, but seasonal variations wore much smaller than variations among the groups. Although dominance reduced neither the frequency of agonistic behavior nor the time and energy spent in chasing, it nay be advantageous in curtailing harmful confrontations and enhancing the establishment of tolerance among some individuals.

No description available.