Experimental evidence for chick discrimination without recognition in a brood parasite host.
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Recognition is considered a critical basis for discriminatory behaviours in animals. Theoretically, recognition and discrimination of parasitic chicks are not predicted to evolve in hosts of brood parasitic birds that evict nest-mates. Yet, an earlier study showed that host reed warblers (Acrocephalus scirpaceus) of an evicting parasite, the common cuckoo (Cuculus canorus), can avoid the costs of prolonged care for unrelated young by deserting the cuckoo chick before it fledges. Desertion was not based on specific recognition of the parasite because hosts accept any chick cross-fostered into their nests. Thus, the mechanism of this adaptive host response remains enigmatic. Here, I show experimentally that the cue triggering this 'discrimination without recognition' behaviour is the duration of parental care. Neither the intensity of brood care nor the presence of a single-chick in the nest could explain desertions. Hosts responded similarly to foreign chicks, whether heterospecific or experimental conspecifics. The proposed mechanism of discrimination strikingly differs from those found in other parasite-host systems because hosts do not need an internal recognition template of the parasite's appearance to effectively discriminate. Thus, host defences against parasitic chicks may be based upon mechanisms qualitatively different from those operating against parasitic eggs. I also demonstrate that this discriminatory mechanism is non-costly in terms of recognition errors. Comparative data strongly suggest that parasites cannot counter-evolve any adaptation to mitigate effects of this host defence. These findings have crucial implications for the process and end-result of host-parasite arms races and our understanding of the cognitive basis of discriminatory mechanisms in general. (+info)
Early determinants of smoking in adolescence: a prospective birth cohort study.
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In a prospective birth cohort study in Brazil, the prevalence and early risk factors for smoking in adolescence were investigated. All 1982 hospital-born children in Pelotas, Rio Grande do Sul, Brazil, were enrolled in a birth cohort study (N = 5,914; boys: 3,037; girls: 2,877). All male participants were searched in 2000 when enrolling in the national army, and 78.8% were traced. In 2001, a systematic sample of 473 girls was interviewed, representing a follow-up rate of 69.1%. Among males, 48.6% (95%CI: 46.6-50.7) had ever tried smoking and 15.8% (95%CI: 14.3-17.3) were daily smokers. Among females, 53.1% (95%CI: 48.6-57.6) had ever tried smoking and 15.4% (95%CI: 12.1-18.7) were daily smokers. Boys born to single mothers and those with fathers with low schooling were more likely to smoke in adolescence. Girls from low-income families, with mothers who smoked during pregnancy, and fathers with alcohol-related problems were more likely to smoke. Although the smoking prevalence was similar in boys and girls, risk factors for smoking were different between the sexes. Social environment appears to be the strongest predictor of tobacco use in adolescence. (+info)
Stability and value of male care for offspring: is it worth only half the trouble?
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Models of parental investment often assume a trade-off for males between providing care and seeking additional mating opportunities. It is not obvious, however, how such additional matings should be accounted for in a consistent population model, because deserting males might increase their fertilization success at the cost of either caring males, other deserting males or both. Here, we present a game theory model that addresses all of these possibilities in a general way. In contrast to earlier work, we find that the source of deserting males' additional matings is irrelevant to the evolutionary stability of male care. We reject the claim that fitness gains through male care are intrinsically less valuable than those through desertion, and that the former must therefore be down-weighted by 1/2 when compared with the latter. (+info)
Germ-line chimerism and paternal care in marmosets (Callithrix kuhlii).
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The formation of viable genetic chimeras in mammals through the transfer of cells between siblings in utero is rare. Using microsatellite DNA markers, we show here that chimerism in marmoset (Callithrix kuhlii) twins is not limited to blood-derived hematopoietic tissues as was previously described. All somatic tissue types sampled were found to be chimeric. Notably, chimerism was demonstrated to be present in germ-line tissues, an event never before documented as naturally occurring in a primate. In fact, we found that chimeric marmosets often transmit sibling alleles acquired in utero to their own offspring. Thus, an individual that contributes gametes to an offspring is not necessarily the genetic parent of that offspring. The presence of somatic and germ-line chimerism may have influenced the evolution of the extensive paternal and alloparental care system of this taxon. Although the exact mechanisms of sociobiological change associated with chimerism have not been fully explored, we show here that chimerism alters relatedness between twins and may alter the perceived relatedness between family members, thus influencing the allocation of parental care. Consistent with this prediction, we found a significant correlation between paternal care effort and the presence of epithelial chimerism, with males carrying chimeric infants more often than nonchimeric infants. Therefore, we propose that the presence of placental chorionic fusion and the exchange of cell lines between embryos may represent a unique adaptation affecting the evolution of cooperative care in this group of primates. (+info)
Drug-abusing fathers: patterns of pair bonding, reproduction, and paternal involvement.
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Despite concerns about compromise of fathering as a public policy issue, very little is known about the status of drug-abusing men as parents. In this pilot study, 50 men enrolled in methadone maintenance treatment completed a structured research interview designed to generate basic information about patterns of pair bonding, reproduction, and paternal involvement. Descriptive analysis of these data highlighted a number of trends in the nature of fathering that, although at odds with popular stereotypes, were similar to trends noted in research conducted with other populations of disenfranchised men. Consistent with a developmental-ecological perspective on parenting, the findings suggest that historical and situational influences interact within this population to compromise socially responsible efforts to function as a parent. The results also raise questions about the extent to which public policy initiatives designed to promote more responsible fathering are reaching this population, and they highlight ways that the drug abuse treatment system might better support men interested in being a more effective parent. (+info)
Relative prenatal and postnatal maternal contributions to schizophrenia-related neurochemical dysfunction after in utero immune challenge.
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Prenatal exposure to infections represents a risk factor for the emergence of neuropsychiatric disorders in later life, including schizophrenia and autism. However, it remains essentially unknown whether this association is primarily attributable to prenatal and/or postnatal maternal effects on the offspring. Here, we addressed this issue by dissecting the relative contributions of prenatal inflammatory events and postnatal maternal factors in an animal model of prenatal viral-like infection. Pregnant mice were exposed to the inflammatory agent polyriboinosinic-polyribocytidilic acid (PolyI:C; 5 mg/kg, i.v.) or vehicle treatment on gestation day 9, and offspring born to PolyI:C- and vehicle-treated dams were cross fostered to surrogate rearing mothers that had either experienced inflammatory or sham treatment during pregnancy. We demonstrate that a variety of dopamine- and glutamate-related pharmacological and neuroanatomical disturbances emerge after prenatal immune challenge regardless of whether neonates were raised by vehicle- or PolyI:C-exposed surrogate mothers. However, the adoption of prenatal control animals to immune-challenged surrogate mothers was also sufficient to induce specific pharmacological and neuroanatomical abnormalities in the fostered offspring. Multiple schizophrenia-related dysfunctions emerging after prenatal immune challenge are thus mediated by prenatal but not postnatal maternal effects on the offspring, but immunological stress during pregnancy may affect postpartum maternal factors in such a way that being reared by an immune-challenged surrogate mother can confer risk for distinct forms of psychopathology in adult life. (+info)
What do parents expect antenatally and do babies teach them?
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Antenatal inquiry of 658 parents in the North Staffordshire District Health Authority showed at least 13% to lack knowledge about a baby's potential for personal interaction when under 1 week old. Mothers and fathers varied significantly, independent of parity. Experienced parents expected later smiles. Two hundred and seventy eight of the same families were questioned three to four months after birth. Most parents had observed their baby's early responsiveness. Specific responses (Looking, listening) were noted earlier when anticipated and looked for. Significant among postnatal non-responders was their antenatal selection of predominantly impersonal stimulation for a baby. The greatest degree of warmth noted in postnatal observations correlated notably with a father's antenatal interest and postnatal support from him and their friends, a mother's commitment to breast feeding and her knowledge that a very young baby can see, like faces, and cries for emotional reasons. This highlights areas for antenatal tuition and postnatal encouragement, aiming to enhance warm early mutual regard between parents and child. (+info)
Do parents who smoke underutilize health care services for their children? A cross sectional study within the longitudinal PIAMA study.
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BACKGROUND: A higher prevalence of respiratory symptoms and an associated increase in health care utilization among children with parents who smoke is to be expected. From previous studies however, it appears that parents who smoke may underutilize health services for their children, especially with respect to respiratory care. This study explores the validity and generalizability of the previous assumption. METHODS: Data were obtained from a Dutch birth-cohort study; the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) project. Information regarding parental smoking, the child's respiratory symptoms and health care use and potential confounders were obtained by postal questionnaires. Multivariate logistic models were used to relate parental smoking to the child's respiratory symptoms and health care use. RESULTS: The study comprised 3,564, 4-year old children. In the crude analysis, respiratory symptoms were more frequent among children with a parent who smoked, while health care utilization for respiratory symptoms was not significantly different between children with or without a parent who smoked. In the multivariate analyses, maternal smoking had a larger impact on the child's respiratory symptoms and health care use as compared to paternal smoking. Maternal smoking was positively associated with mild respiratory symptoms of the child, adjusted odds ratio [AOR] 1.50 (1.19-1.91), but not with severe respiratory symptoms AOR 1.03 (0.75-1.40). Among children with mild respiratory symptoms, children with a mother who smoked were less likely to be taken to the general practitioner (GP) for respiratory symptoms, than children with mothers who did not smoke, AOR 0.58 (0.33-1.01). This finding was less pronounced among children with severe respiratory symptoms AOR 0.86 (0.49-1.52). Neither GP visits for non-respiratory symptoms nor specialized care for respiratory disease were significantly associated with parental smoking. CONCLUSION: Mothers who smoke appear to underutilize health care for their children with mild respiratory symptoms. Health care workers should be informed about this phenomenon. Inquiring after the respiratory health of the children during regular visits to healthy baby clinics may help to track potential underutilization of care. (+info)