No abstract

In the study, 63 American preschool children (mean age 4 years, 8 months) were approached and read stories by adult testers who displayed high versus low frequencies of smiling and gaze. After being read to, the testers elicited self-disclosure from the children and later the children rated the trustworthiness and likeability of the tester (rapport measures). As additional measures of rapport, the children's smiling, gaze, and lack of nervousness in the interactions were observed. The results indicated that the development of rapport with children was greater when the adult tester displayed high rather than low frequencies of smiling but not gaze. Children's shyness also contributed to the development of rapport. Shyness was negatively associated with rapport perceptions/behaviours and, in the case of attributed trustworthiness, moderated the effects of adults' gaze.

No abstract

The cost of reproduction theory posits that there are trade-offs between current and future reproduction because resources that are allocated to current offspring cannot be used for future reproductive opportunities. Two adaptive reproductive strategies have been hypothesized to offset the costs of reproduction and maximize lifetime fitness. The terminal investment hypothesis predicts that as individuals age they will allocate more resources to current reproduction as a response to decreasing residual reproductive value. The reproductive restraint hypotheses predicts that as individuals age they will allocate fewer resources to current reproduction to increase the chance of surviving for an additional reproductive opportunity. In this study, we test for adaptive responses to advancing age in male burying beetles, Nicrophorus orbicollis. Burying beetles use facultative biparental care, but the male typically abandons the brood before the female. Previous work in male burying beetles has suggested several factors to explain variation in male residency time, but no study has observed male behavior throughout their entire reproductive lifetimes to determine whether males change residency time in an adaptive way with age. We compared residency time of males that reproduced biparentally, uniparentally, and on different-sized carcasses to determine if they used an adaptive reproductive strategy. Males did not increase residency time as they aged when reproducing biparentally, but decreased residency time with age when reproducing uniparentally. A decrease in parental care with age is consistent with a reproductive restraint strategy. When female age increased over time, males did not increase their residency time to compensate for deteriorating female condition. To our knowledge, this is the first test of adaptive reproductive allocation strategies in male burying beetles.