Home About us Contact
|
Home About us Contact | ||
|
|
||
Adult Behaviour (adult + behaviour)
Selected AbstractsTemperature and hen harrier productivity: from local mechanisms to geographical patternsECOGRAPHY, Issue 5 2002S. M. Redpath Climate is an important factor limiting demography and distribution patterns in many organisms. For species with a broad geographical distribution, the mechanism by which climate influences demography is likely to vary dramatically from one end of the range to the other. In this paper we first assess, in a Scottish population of hen harriers Circus cyaneus, how temperature and rainfall influence adult behaviour and chick mortality patterns at the nest. We then test for associations between harrier productivity and weather across Scotland, towards the northern edge of the range, and Spain, towards the southern edge of the range. We show that during the nestling period, female brooding time increased in cold weather. Male provisioning rate was negatively related to temperature and rainfall. Chick mortality increased in cold temperatures and was most likely to occur at nests where male prey delivery rates were low relative to temperature. Annual values of harrier fledged brood size across Scotland were positively related to summer temperature suggesting that the patterns seen in one population held at a national scale. In Spain, however, the opposite patterns were observed with fledged brood size being negatively related to temperature. This shows that whilst the impact of weather on productivity may be equally strong at two ends of a geographical range, the mechanisms vary dramatically. Large-scale predictive models need to take such patterns into account. [source] Sex-Specific Aggression and Antipredator Behaviour in Young Brown TroutETHOLOGY, Issue 7 2001Jörgen I. Johnsson Sex differences in adult behaviour are often interpreted as consequences of sexual selection and/or different reproductive roles in males and females. Sex-specific juvenile behaviour, however, has received less attention. Adult brown trout males are more aggressive than females during spawning and juvenile aggression may be genetically correlated with adult aggression in fish. We therefore tested the prediction that immature brown trout males are more aggressive and bolder than immature females. Because previous work has suggested that precocious maturation increases dominance in salmonids, we included precocious males in the study to test the prediction that early sexual maturation increase male aggression and boldness. Aggression and dominance relations were estimated in dyadic contests, whereas boldness was measured as a response to simulated predation risk using a model heron. Independent of maturity state, males initiated more than twice as many agonistic interactions as females in intersexual contests. However, males were not significantly more likely to win these contests than females. The response to a first predator attack did not differ between sex categories, but males reacted less to a second predator attack than females. Sexual maturity did not affect the antipredator response in males. Since there is no evidence from field studies that stream-living immature male and female salmonids differ in growth rate, it appears unlikely that the sex differences demonstrated are behavioural consequences of sex-specific investment in growth. It seems more likely that sex-specific behaviour arises as a correlated response to sexually selected gene actions promoting differential behaviour in adult males and females during reproduction. Alternatively, sex differences may develop gradually during juvenile life, because a gradual developmental program should be less costly than a sudden behavioural change at the onset of sexual maturity. [source] Experiences of alcohol drinking among Swedish youths with type 1 diabetesEUROPEAN DIABETES NURSING, Issue 1 2009A Leger RN Diabetes Nurse Abstract Background: Alcohol consumption in Europe and North America is greatest in 18,25-year-olds. This behaviour can be seen as a transitional stage from childhood to adulthood, where consuming alcohol is perceived as a typical feature of adult behaviour. Youths often start to consume alcohol when they are 14,15 years of age, and one in five youngsters around 15 years of age report binge drinking. Studies of alcohol consumption among youths with type 1 diabetes have not been undertaken but it is well known that, in these people, alcohol drinking can cause hypoglycaemia and worsen the capacity to feel and interpret the symptoms of hypoglycaemia. Aim: The overall aim was to explore experiences of alcohol consumption among youths with type 1 diabetes. Another objective was to identify strategies as to how they deal with situations when they drink alcohol. Methods: Semistructured interviews with ten 18-year-old youths with type 1 diabetes, using Burnard's content analysis method. Results: This study illustrates that informants strive for security, independence and control. Frequency of binge drinking did not seem to differ from rates in other teenagers. Informants exposed themselves to considerable risks and many had met with serious incidents. Moreover, the result exemplifies how symptoms of diabetic ketoacidosis (such as nausea and vomiting) can easily be misinterpreted as a hang-over or gastroenteritis. Informants lacked age-appropriate knowledge about diabetes and the effects of alcohol, but had tested things out themselves; some involved their friends in their diabetes treatment. Moreover, three strategies occurred with the aim of normalisation and security: the 'low-consumption' strategy, the ,ambitious' strategy and the ,rather-high-than-dead' strategy. Fear of hypoglycaemia was a significant concern and the consequence was poor diabetes control. Conclusion: To increase youths' independence and security, the diabetes care team should provide adequate and relevant information about alcohol. Treatment plans might contain practical steps such as advice about responsible alcohol intake and adjustments of insulin and meals, and could also encourage young people with diabetes to carry diabetes ID and inform friends about hypoglycaemia (and how to handle situations involving alcohol). Copyright © 2009 FEND [source] Testosterone response to GnRH in a female songbird varies with stage of reproduction: implications for adult behaviour and maternal effectsFUNCTIONAL ECOLOGY, Issue 4 2007JODIE M. JAWOR Summary 1Despite considerable recent interest in plasma and yolk testosterone (T) in female birds, relatively little is known about environmental regulation of female T, individual variation in female T or the relationship between plasma and yolk T. 2In breeding females of a wild population of dark-eyed junco (Junco hyemalis), we assessed variation in the responsiveness of the hypothalamo-pituitary-gonadal (HPG) axis to a challenge with gonadotropin-releasing hormone (GnRH) by measuring circulating T before and 30 min after a standardized injection of GnRH. We asked whether response to challenge varied seasonally or with stage of reproduction and whether it was repeatable within individuals or related to T deposited in eggs. 3Initial and post-challenge levels of T were measured using enzyme immunoassay. In a subset of these females, luteinising hormone (LH) was measured using radioimmunoassay (RIA). In addition, eggs were collected from nests of 15 females that had received a GnRH challenge, and yolk T was measured using RIA. 4During most of the breeding season, plasma T did not increase in response to GnRH. GnRH consistently caused increases in plasma T only during the 7 days before oviposition, when females were rapidly depositing yolk in eggs but had not yet begun to lay them. Among a small subset of females we found a positive correlation between the magnitude of this increase in plasma T in response to GnRH during egg development and the amount of T deposited in the yolk of eggs collected at a later time. 5These results suggest that ovarian response to GnRH-induced increases in LH is greatest when females are actively depositing yolk into eggs. Factors that stimulate the release of GnRH during egg formation may result in higher levels of plasma T which could influence adult female behaviour. Further, because plasma T was correlated with later yolk T, factors that stimulate GnRH release may also lead to higher levels of yolk T potentially influencing offspring development or behaviour. [source] Fetal programming and fetal psychologyINFANT AND CHILD DEVELOPMENT, Issue 1 2010Peter T. Ellison Abstract The introduction of the ,fetal programming hypothesis', first in epidemiology, subsequently in a broad range of disciplines concerned with developmental biology, has generated new interest in phenotypic plasticity, the mechanisms that govern it, and its place in evolutionary biology. A number of epidemiological studies link small size at birth, assumed to be a consequence of constrained prenatal energy availability, with adverse effects on the risk of chronic diseases later in life. The cluster of chronic diseases associated with the metabolic syndrome and alterations of glucose metabolism are particularly implicated. Recent evidence suggests that epigenetic modification of gene expression affecting the hypothalamic-pituitary-adrenal (HPA) axis may be involved in these effects. In animal studies epigenetic alteration of HPA axis activity and responsiveness is associated with changes in adult behaviour and stress responsiveness. The potential for similar effects to contribute to psychological and psychiatric outcomes in humans has been explored in a number of contexts, including famine exposure, observed covariance with birth weight, and prenatal dexamethasone treatment of fetuses at risk of congenital adrenal hyperplasia. While fetal programming effects have now been widely demonstrated across species and human populations, the adaptive significance of these effects is still a matter of debate. Copyright © 2010 John Wiley & Sons, Ltd. [source] The biology of Agriotes sordidus Illiger (Col., Elateridae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2004L. Furlan Abstract:, This paper describes the life cycle, including adult behaviour, oviposition, larval and pupal development rate of Agriotes sordidus Illiger. Each larva passed through up to eight to 13 instars. The larval size range of each instar was defined. Larvae need live vegetable tissues to survive and grow, otherwise most die within 40 days. Resistance to starvation increases with the age of the larvae (last instars can survive up to 1 year without food at 20°C). Each instar passes through three phases: mandible hardening and darkening, feeding, pre-moulting. The intense feeding (damaging plants) phase lasted <25% of the whole development time. They are poliphagous and the rate of larval development does not vary with host-plant type (maize, alfalfa). Provided sufficient soil moisture and food are present, larval development rate strongly depends on soil temperature. The duration of each instar increased with the age of the larvae. No larval growth was observed below 9°C. Under laboratory conditions the average heat sum (above a base of 9°C) required for development from egg to adult was about 3900 DD. Similar results were found in the rearing cages and in the open field. At the latitudes of the regions where this study was carried out (northern Italy, Veneto between 45°34,00,,N and 45°42,00,,N and central-south Italy, Molise, between 41°49,720,,N and 41°56,501,,N) the 6th instar (which normally is the first one passing 10 mm in length) is attained by September of the same oviposition year. Pupae can be found between the end of May and September mostly in the upper soil layer. Their transformation into adults took about 16 days at 25°C. Larvae of different stages overwintered by burrowing deep into the soil. Vertical migrations during the year are described: they depend mostly on soil temperatures from October to early spring. The adults overwintered and laid eggs in the subsequent spring. At lower latitudes or in warm seasons most of the population completed its life cycle (from egg to egg) in 24 months over three calendar years. At more northern latitudes, part (sometimes most) of the population completed the whole life cycle in about 36 months over four calendar years. [source] | ||||||||||