966 resultados para Territorial Aggression


Relevância:

70.00% 70.00%

Publicador:

Resumo:

Past studies into the roles of testosterone in birds have focused on species that occur in temperate regions. In such species, plasma testosterone levels are high during the establishment of territories in the spring and are associated with increased aggression. In contrast to most temperate species, tropical birds frequently defend territories year-round, during which time territoriality often occurs in a nonsexual context. The few studies that have been carried out on tropical birds show lower levels of circulating testosterone than occur in their temperate counterparts. In some year-round territorial tropical species, testosterone and aggression are dissociated, while in other species testosterone still plays a role in regulating aggression. This study examined the relationship between aggression and plasma testosterone levels in a year-round territorial, subtropical population of the buff-banded rail with characteristics typical of tropical species. Peak testosterone levels were substantially lower than those found in temperate species. Males displayed a seasonal peak in plasma testosterone level when their partners were most likely to be fertile. At other times, testosterone levels were mostly undetectable, despite year-round territoriality. We found that T levels increased with courtship behavior but showed no relationship with aggression, supporting the hypothesis that dissociation between testosterone and territoriality may be widespread among tropical avian taxa. (C) 2003 Elsevier Science (USA). All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Fecal samples and behavioral data were collected at a fortnightly basis during 11 months period from free-living male American kestrels living in southeast Brazil (22 degrees S latitude). The aim was to investigate the seasonal changes in testicular and adrenal steroidogenic activity and their correlation to reproductive behaviors and environmental factors. The results revealed that monthly mean of fecal glucocorticoid metabolites in May and June were higher than those estimated in November. in parallel, monthly mean of androgen metabolites in September was higher than those from January to April and from October to November. Molt took place from January to March, whereas copulation was observed from June to October but peaked in September. Nest activity and food transfer to females occurred predominantly in October, and parental behavior was noticed only in November. Territorial aggressions were rare and scattered throughout the year. Multiple regression analysis revealed that fecal androgen levels are predicted by photoperiod and copulation, while fecal glucocorticoid levels are only predicted by photoperiod. Bivariate correlations showed that fecal androgen metabolites were positively correlated with fecal glucocorticoid metabolites and copulation, but negatively correlated with molt. Additionally, copulation was positively correlated with food transfer to females and nest activity, but negatively correlated with molt. These findings suggest that male American kestrels living in southeast Brazil exhibit significant seasonal changes in fecal androgen and glucocorticoid concentrations, which seem to be stimulated by decreasing daylength but not by rainfall or temperature. (C) 2009 Elsevier Inc. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Land take is a phenomenon of great concern nowadays because of the large number of its negative impacts regarding biological, economic and social balance. In Italy, the development of urban and other artificial land has been irreversibly transforming a nonrenewable resource such as soil, regardless the almost constant population rate, with different speed depending of the region considered. The aim of this paper is to analyze the phenomenon in the metropolitan area of Naples, which is an area highly affected by territorial aggression of human matrix. The data used are both by the Institute for Environmental Protection and Research (ISPRA) Report 2015 on the usage of the land and by ISTAT relating to the resident population up to the 1st of January 2015 and the extension of land for agricultural use (Census 2010). The mathematical combination of this data creates a new indicator that can be referred to as “residual land”; this residual area is of great extension with many different characteristics and it could represent the area where the phenomenon of land take most occurs. The identification, measurement and analysis of “residual land” provide new insights on the evolution of land take and this new indicator can represent a critical element to work on to prevent future land transformation and protect natural and agricultural areas within the Italian context.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Understanding the role of multiple colour signals during sexual signalling is a central theme in animal communication. We quantified the role of multiple colour signals (including ultraviolet, UV), measures of body size and testosterone levels in settling disputes between male rivals in an elaborately ornamented, African lizard, played out in a large 'tournament' in the wild. The hue and brightness (total reflectance) of the UV throat in Augrabies flat lizards, Platysaurus broadleyi, as well as body size, were consistent and strong predictors of 'fighting ability'. Males with high fighting ability were larger and displayed a UV throat with low total reflectance. In contrast, males with low fighting ability were smaller and had violet throats with broader spectral reflectance curves (higher total reflectance). As fighting ability is associated with alternative reproductive tactics in this system (territorial versus floater), we also examined the role of colour signals in predicting male reproductive tactic. Territorial males had UV throats with higher chroma but had poorer body condition than floater males, probably because of the energetic costs of maintaining a territory. Although testosterone was not a significant predictor of fighting ability or reproductive tactic, it was correlated with the hue of the UV throat, suggesting that testosterone may impose some constraint on signal expression. Lastly, we show that within the context of the natural signalling environment, UV-reflective throats constitute a conspicuous, effective signal that male Augrabies flat lizards use to advertise their status honestly to rivals. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This study evaluated the effect of dietary supplementation with -tryptophan (L-TRP), a serotonin precursor, on the aggressiveness of juvenile matrinx . Fish were kept in individual aquaria for 7 days receiving the diets: D1 (control: 0.47% of TRP), D2 (0.94% of TRP), D3 (1.88% of TRP), and D4 (3.76% of TRP). After this, they were grouped with an intruder fish to establish a resident-intruder relationship during periods of 20 min. Blood cortisol, glucose, chloride, sodium and calcium; hemoglobin, hematocrit, red blood cell count and volume; liver glycogen and lipids were measured. Territoriality had significant effect on the aggressiveness of matrinx (the residents were more aggressive than intruders, < 0.001) and tryptophan significantly affected their behavior. Fish fed with the D2 diet presented a longer latency until the first attack ( = 0.0069) and bit the intruder fewer times ( = 0.0136) during the period of observation, compared to the control group. The frequency of bites and chases after the first attack was not affected by the dietary supplementation of TRP. Physiological variables were not significantly affected by the diet, except for a moderate increase in cortisol level in fish fed with D2 diet after the fight, indicating slight activation of the hypothalamus-pituitary-interrenal axis. The results show that juvenile matrinx have aggressive and territorial behavior and that a diet containing 9.4 g TRP kg(-1) alter their aggressiveness, without affecting the stress-related physiological parameters.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Dominant species are those which delimit and defend territories from other individuals of the same or different species. Subordinate species are those which, furtive and sneakily, use sources of nectar from other individuals. This study aimed to describe the aggressive interactions between species of hummingbirds, define which species are dominant and which are subordinate, investigate if the sharing of resources occurs during the visits, and compare the behaviour of the dominant species in different strata (tree, arbustive and herbaceous). The species observed interacting with Anthracothorax nigricollis Vieillot 1817 were Phaethornis pretrei Lesson and Delattrer 1839, Thalurania furcata Gmelin 1788, and Polytmus guainumbi Pallas 1764. Nine behavioural acts grouped into four categories were identified and described. The dominant species is A. nigricollis (with 0.9 of the attacks), followed by T. furcata (with 0.07) and P. pretrei (with 0.03). The resource sharing was seen only in the shrub layer, in C. surinamensis, in which there was intraspecific and interspecific sharing. A. nigricollis showed higher interspecific toleration, T. furcata (0.27) and P. pretrei (0.55) than intraspecific A. nigricollis (0.18). The frequency of occurrence of behaviours expressed by A. nigricollis in the three vegetation strata differed significantly.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Environmental enrichment seeks to improve the behavior of captive animals. Few studies have developed enrichment strategies for fish, particularly for use in aquaculture. Environmental enrichment for territorial and aggressive animals has the potential to increase both the amount of defensible resources and the value of a disputed territory which can increase the level of aggression. This study evaluated this hypothesis for the redbreast tilapia, Tilapia rendaIli. We used a short-term approach for evaluation of fish aggressive behavior by recording it for 30 min after introduction of a pair of fish into each experimental aquarium. Our main finding was that the latency to start a fight was lower in an enriched environment, but the frequency of attacks was higher in a non-enriched environment (control). Furthermore, we observed clear hierarchical behavior (submissive dark stripes on the body and dominant light-colored bodies without stripes) only in the non-enriched environment. Structural enrichment of the environment for redbreast tilapia leads to decreased aggression and cohabitation without hierarchical dominance. © 2013 Copyright Taylor and Francis Group, LLC.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In many territorial species androgen hormones are known to increase in response to territorial intrusions as a way to adjust the expression of androgen-dependent behaviour to social challenges. The dear enemy effect has also been described in territorial species and posits that resident individuals show a more aggressive response to intrusions by strangers than by other territorial neighbours. Therefore, we hypothesized that the dear enemy effect may also modulate the androgen response to a territorial intrusion. Here we tested this hypothesis in male cichlid fish (Mozambique tilapia, Oreochromis mossambicus) using a paradigm of four repeated territorial intrusions, either by the same neighbour or by four different unfamiliar intruders. Neighbour intruders elicited lower aggression and a weaker androgen response than strangers on the first intrusion of the experiment. With repeated intrusions, the agonistic behaviour of the resident males against familiar intruders was similar to that displayed towards strangers. By the fourth intrusion the androgen response was significantly reduced and there was no longer a difference between the responses to the two types of intruders. These results suggest that the dear enemy effect modulates the androgen response to territorial intrusions and that repeated intrusions lead to a habituation of the androgen response.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

From the Introduction. Russia’s annexation of Crimea and its aggression in eastern Ukraine have triggered a debate about the main directions of defence policy in the Nordic and Baltic region. In the Baltic states, but also in the Nordic countries and Poland, much attention is being paid to questions of Territorial Defence Forces (TDF). TDF are viewed as one of the elements in the national defence systems’ response during the early stages of a hybrid conflict. The Baltic states have decided to adapt their Territorial Defence Forces to new threats by making a number of changes to their functioning, depending on the local conditions in each case. Given the growing uncertainty in the region, they have opted not to undertake any in-depth reforms of TDF at this stage, as that could entail a temporary disorganisation in the armed forces. In the coming years Estonia, Latvia and Lithuania will invest in increasing the size and combat readiness of their Territorial Defence Forces, providing them with better training and equipment, and creating a system of incentives to encourage more people to serve in volunteer formations.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: To review the literature about the use of atypical antipsychotics in the treatment of pathological aggression in children and adolescents. Method: The databases MEDLINE, SciELO, and LILACS were searched for publications in Portuguese or English from 1992 to August 2011 using the following keywords: mental disease, child, adolescent, treatment, atypical antipsychotic, aggressive behavior, aggression, and violent behavior. Results: Sixty-seven studies of good methodological quality and clinical interest and relevance were identified. Studies including children and adolescents were relatively limited, because few atypical antipsychotics have been approved by the Food and Drug Administration (FDA). All the medications included in this review (risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole and clozapine) have some effectiveness in treating aggression in children and adolescents, and choices should be based on clinical indications and side effects. Conclusions: There are few studies about the effectiveness and safety of atypical antipsychotics for the pediatric population, and further randomized controlled studies with larger groups of patients and more diagnostic categories, such as severe conduct disorder and oppositional defiant disorder, should be conducted to confirm the results reported up to date and to evaluate the impact of long-term use.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

It is a generally acknowledged fact that the dynamics of frontier advance deeply influenced the broad experience of American post colonial societies. The colonization, which started most from the east boundaries of the continent, appropriated and gradually transformed the American territories from east to west. The advance, initially represented by the arrival of the European settlers, went on to become an important trace of that society which did not come to know any physical limits of a restricted territory. However, despite the common identity granted by these territorial dynamics, the later developments and consequences seem to have shaped differently the Northern representatives from their Southern counterparts. In addition, the interpretation of these facts bore in each of these regions different meanings and traits.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Entre 1852 e 1859, a atual Argentina se encontrava politicamente dividida entre Buenos Aires e a Confederação, que congregava as demais Províncias. Nesse período, diferentes grupos étnicos dos pampas, dos Andes e da Patagônia se organizaram em confederações indígenas com o objetivo de enfrentar os avanços territoriais, defender suas autonomias e a participação em lucrativas redes de comércio. Nesta luta por autonomia política, territorial e comercial, negociaram com os grupos criollos em luta pelo poder, avaliaram seus projetos e aderiram a aquele que os reconheceu enquanto interlocutores políticos e aliados militares. Participantes ativos da política argentina, conseguiram reconquistar territórios e oferecer intensas resistências aos criollos.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The eye lenses of Parma microlepis from the rocky barrens of Sydney (New South Wales, Australia) were found to contain Ba, Hg, Rb, and Sr at concentrations above the quantitative detection limits of solution-based inductively-coupled plasma-mass spectrometry (ICP-MS). Lenses were separated into the hard central nucleus and the softer surrounding cortex. Nuclei contained lower (equal for Ba) concentrations of these metals. Biochemical analysis of the protein composition of these lenses revealed differences in the ratio of gamma-crystallin to beta-crystallin in the lens nucleus and cortex. These changes were shown to be attributable both to protein degradation and changes in protein synthesis as fish age. Such changes may lead to the loss of sequestered metals from older cell layers, or change the affinity of new layers for particular trace metals. Differential binding affinities of these crystallins may, therefore, partially account for trace-metal differences observed in the lens nucleus and cortex.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This special section brings together 4 of the 12 studies conducted within a research program analyzing the relationships among social mobilization, governance. and rural development in contemporary Latin America. The introduction Lives an overview of the contemporary significance of social movements For rural development dynamics in the region, and of the principal insights of the section papers and the broader research program of which they were a part. This significance varies Lis an effect of two distinct and uneven geographics: the geography of social movements themselves and the geography of the rural political economy. The effects that movements have oil the political economy of rural development also depend significantly oil internal characteristics of these movements. The paper identifies several such characteristics. The general pattern is that movements have had far more effect oil widening the political inclusiveness of rural development than they have oil improving its economic inclusiveness and dynamism. (c) 2008 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The incentives and governance system of organizations are important in explaining how they behave in localized development processes. This article builds on the observation that the literature on territorial development does not generally address the action of social movements. At the same time, research on social movements rarely studies their effects on the territories ill which they act. This text is a contribution to fill this gap. It compares two social movement organizations: a trade union federation and a credit cooperative system operating throughout southern Brazil, Both organizations share common origins and social bases, yet their impacts oil territories have been quite different. The analysis focuses Oil the social ties that link trade unions and cooperatives to their territories to show that governance systems may explain the performance of each organization, especially with regard to their capacity for innovation. (c) 2008 Elsevier Ltd. All rights reserved.