Imprinting: drug-produced isolation and the sensitive period.
Explore the source record for details and available documents.
SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Drawing on the concepts and theory of dominance in adult vertebrates, this article categorizes the relationships of dominance between infant siblings, identifies the behavioral mechanisms that give rise to those relationships, and proposes a model to explain their evolution. Dominance relationships in avian broods can be classified according to the agonistic roles of dominants and subordinates as "aggression-submission," "aggression-resistance," "aggression-aggression," "aggression-avoidance," "rotating dominance," and "flock dominance." These relationships differ mainly in the submissiveness/pugnacity of subordinates, which is pivotal, and in the specificity/generality of the learning processes that underlie them. As in the dominance hierarchies of adult vertebrates, agonistic roles are engendered and maintained by several mechanisms, including differential fighting ability, assessment, trained winning and losing (especially in altricial species), learned individual relationships (especially in precocial species), site-specific learning, and probably group-level effects. An evolutionary framework in which the species-typical dominance relationship is determined by feeding mode, confinement, cost of subordination, and capacity for individual recognition, can be extended to mammalian litters and account for the aggression-submission and aggression-resistance observed in distinct populations of spotted hyenas and the "site-specific dominance" (teat ownership) of some pigs, felids, and hyraxes. Little is known about agonism in the litters of other mammals or broods of poikilotherms, but some species of fish and crocodilians have the potential for dominance among broodmates.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The importance of general environmental, including visual and tactile, stimuli on behavior and prolactin secretion during the incubation phase of reproduction in the duck (Anas platyrhynchos) was investigated. Nest occupancy rapidly increased at the end of egg laying and marked the initiation of incubation. Two recesses from the nest each day were synchronized to dawn and dusk; the median occurrence was 0.23 hr after dawn and 1.17 hr before dusk. Mean recess length was 36.1 +/- 1.9 min at dawn and 40.5 +/- 2.1 min at dusk. Plasma prolactin concentrations during incubation, 25.8 +/- 2.3 ng/ml, decreased to baseline levels, 10.8 +/- 1.9 ng/ml, within 24 hr after nestbox removal. The withdrawal of tactile, but not visual, stimuli of the clutch during incubation by either anesthesia or denervation of the incubation patch caused significant decreases in prolactin plasma concentrations within 24 hr. Prolactin plasma concentrations decreased rapidly at the end of incubation in ducks which successfully hatched young as well as in unsuccessful incubators. Temperature manipulations of the clutch, either above or below normal, caused decreases in plasma prolactin concentrations in parallel with temperature modification.
The effects of different peripheral doses of four dopamine (DA) receptor antagonists on general activity and maternal behavior were examined in lactating female rats. Administration of the classic D1-like and D2-like DA receptor blocker haloperidol (0.1 and 0.05 mg/kg) disrupted pup retrieval and nest-building behaviors and reduced motor activity. Pimozide (0.5 and 0.2 mg/kg), which has more affinity for DA D2-like receptors, mildly disrupted pup retrieval while showing no significant influence on open-field behaviors. The putative DA D(4) receptor blocker, clozapine (1.5 and 1.0 mg/kg) reduced motor activity significantly, while only 1.0 mg/kg dose significantly decreased percent of rats displaying nest building. The DA D1-like receptor blocker SKF-83566 (0.2 and 0.1 mg/kg) significantly reduced pup retrieval, nest building and motor activity. These results suggest a role for DA receptors in ongoing maternal behavior that correlates directly with general activity.
Explore the source record for details and available documents.
Most seasonally breeding songbirds display dramatic seasonal fluctuations in plasma testosterone (T) levels and mate attraction behaviors, including song. However, males of some songbird species, such as the European starling (Sturnus vulgaris), continue to sing at high levels after the breeding season, when T levels are basal. In male starlings song during the breeding season functions mainly to attract mates, whereas song during the nonbreeding season appears unrelated to reproduction. This suggests that song produced in a context unrelated to female courtship, unlike song directed toward females, is not regulated by plasma T. In captive males housed in large outdoor aviaries we explored the relationship between plasma T and song produced during the breeding season within and outside a courtship context. This was achieved by determining the effects of castration and subsequent T treatment on song and mate attraction behaviors in both the presence and the absence of a female. Compared to intact males, castrated males did not show reduced song activity in the absence of a female for at least 6 months after the operation, strongly suggesting that the expression of noncourtship song is not regulated by plasma T. Likewise, we found that experimentally elevating T levels in castrated males did not affect noncourtship song rates. However, control castrated males receiving empty implants tended to show reduced noncourtship song rates after implantation. This may have been due to a suppressive effect caused by the presence of the T-implanted castrated males in the same aviary. In contrast, courtship singing was clearly controlled by plasma T: it was abolished by castration and restored by subsequent T replacement when males were housed both individually and in a group situation. High plasma levels of T also appeared necessary for the activation of three other behavioral traits critical for mate attraction, namely, nesthole occupancy, spending time (singing) in a nesthole, and carrying green nesting material into a nesthole.
Explore the source record for details and available documents.
Toxocara canis, the parasitic roundworm of the dog may infect aberrant hosts including mice and humans. The present study examined the behavioral and pathological changes at each of three postintubation periods (Period 1: 8-10 days, 2: 49-51 days, and 3: 84-86 days postintubation, respectively) in independent groups of mice intubated with 1000 eggs of T. canis. Eight-ten days after intubation Toxocara infected animals typically showed depressed levels of activity relative to saline-intubated controls. The scope and severity of behavioral changes were attenuated when different mice were tested 49-51 days after infection, and then became more severe when the third set of animals was tested 84-86 days after intubation. While brain pathology increased over the three periods, visceral organs showed marked pathology 8-10 days after intubation followed by a decrease in severity. These data suggest that Toxocara associated pathological changes in visceral organs and in the brain have behavioral consequences in mice. Given the similarity in migratory pathways of this parasite in rodents and humans, and the findings of T. canis larvae in human brain tissue, the results of this animal study may have implications concerning the possible etiology of behavioral disorders for children who have a known history of pica for dirt.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The effects of food restriction upon mating and pregnancy of female house mice were studied at a warm (21 degrees C) and a cold (5 degrees C) temperature to examine the hypothesis that the effects of temperature and food availability are not independent. Analyses of the data showed significant interaction between temperature and food availability for virtually all variables measured, supporting the initial hypothesis. Contingency analysis of mating, fertility, and litter survivorship showed that the interaction influenced not only the percentage of females successfully producing litters, but also the timing of abandonment of reproductive effort by those females that did not have surviving litters. The percentage of females who mated was reduced only in food-restricted females under cold conditions. Both low temperature and food restriction reduced the percentage of mated females that became pregnant. Food-restricted females under cold conditions who did become pregnant tended to kill their litters at birth. The net effect was an interaction between temperature and food restriction that resulted in females reducing or abandoning reproductive effort at progressively earlier stages of the reproductive cycle. The interaction between temperature and food restriction was further displayed in the growth curves of pregnant females, with the reduction of growth by food restriction being greater in the cold.
Female choice based on multiple male traits has been documented in many species but the functions of such multiple traits are still under debate. The satin bowerbird has a polygynous mating system in which males attract females to bowers for mating; females choose mates based on multiple aspects of males and their bowers. In this paper, we demonstrate that females use some cues to decide which males to examine closely and other cues to decide which males to mate with. Female visitation rates to bowers were significantly related to male size and the males' 'solitary' display rates, and, to a lesser extent, to the numbers of bower decorations. After controlling for female visitation rates, it was found that a male's mating success was significantly related to his size and the rate at which he 'painted' his bower with saliva and chewed up plant material.
We propose a new mechanism for diversification of male nuptial-colour patterns in the rapidly speciating cichlid fishes of Lake Victoria. Sympatric closely related species often display nuptial colours at opposite ends of the spectrum with males either blue or yellow to red. Colour polymorphisms within single populations are common too. We propose that competition between males for breeding sites promotes such colour diversification, and thereby speciation. We hypothesize that male aggression is primarily directed towards males of the common colour, and that rare colour morphs enjoy a negatively frequency-dependent fitness advantage. We test our hypothesis with a large dataset on the distributions and nuptial colorations of 52 species on 47 habitat islands in Lake Victoria, and with a smaller dataset on the within-spawning-site distributions of males with different coloration. We report that territories of males of the same colour are negatively associated on the spawning site, and that the distribution of closely related species over habitat islands is determined by nuptial coloration in the fashion predicted by our hypothesis. Whereas among unrelated species those with similar nuptial colour are positively associated, among closely related species those with similar colour are negatively associated and those with different colour are positively associated. This implies that negatively frequency-dependent selection on nuptial coloration among closely related species is a sufficiently strong force to override other effects on species distributions. We suggest that male-male competition is an important and previously neglected agent of diversification among haplochromine cichlid fishes.
Explore the source record for details and available documents.