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Social experiences, especially during early development, have profound effects on the brain and behaviour in later life. We examined whether the provision of alloparental care by older siblings affects anxiety, sociability and parental behaviour at adulthood in both them and the younger siblings for which they care. Using mandarin voles, Microtus mandarinus, we kept the older litter in the parents'' cage at weaning where they provided alloparental care to younger siblings of the next litter. We found that mandarin voles that had cared for younger siblings displayed significantly more locomotor activity in a novel environment and engaged in more social investigation of unfamiliar same-sex individuals. Females of this group also provided more parental care compared to control voles. Individuals cared for by older siblings demonstrated lower levels of anxiety and aggression, and higher levels of parental investment at adulthood, compared to control animals. These results suggest that providing alloparental care increases locomotor activity, social investigation and maternal care in adulthood, and that receiving alloparental care reduces levels of anxiety and aggression and increases biparental care in adulthood. Giving and receiving alloparental care has clear benefits in this species and suggests that alloparental care may increase the inclusive fitness of both givers and receivers. [Copyright &y& Elsevier]

Abstract: Various hypotheses have been proposed to explain factors influencing male alloparental behavior in cooperatively breeding species. Mandarin voles (Microtus mandarinus) are ideal animal models to investigate these factors because they are highly social rodents and display biparental care and spontaneous parental care when exposed to foster pups. Here we test the idea that the sexual and paternal experience of males influences alloparental behavior toward novel pups, and that these experiences alter the expression of neuropeptide oxytocin (OT) and estrogen receptor alpha (ERα). Alloparental behavior and OT and ERα expression were compared between virgin males that had no prior sexual or reproductive experience, exposed males that with prior exposure to novel pups before the test, paired males that had been housed with a female, and new fathers having their first litter with a female. Our results show that prior exposure to novel pups and prior mating and paternal experience increased male alloparental behavior toward a novel pup. This experience also increased OT expression and affected the expression of ERα. This study reveals important initiation factors for male alloparental behavior and suggests a relationship between alloparental behavior and central OT expression in males. [ABSTRACT FROM AUTHOR]