RESUMEN
This research examines the proximate evaluative mechanisms underlying prosocial partner choice-based reciprocity. Across four studies we presented 855 university undergraduates (online for course credit) and 76 4- to 6-year-olds (offline at a university laboratory) with vignettes describing prosocial, social and non-social characters, and asked participants about their person preferences in prosocial, social and general contexts. Adults demonstrated sophisticated appraisals, coordinating between relevant trait and contextual cues to make selections. Adults were particularly attentive to prosocial cues in costly conditions, suggesting that they were using dispositional attributions to make their selections. By contrast, children were largely unable to integrate trait and contextual cues in determining their partner preferences, instead displaying valenced preferences for non-social cues, suggesting the use of affective tagging. Together, these studies demonstrate that the mechanisms underlying prosocial, partner choice-based reciprocity are not early emerging and stable but show considerable development over the lifespan.
RESUMEN
The determination of plant foliar water use efficiency will be of great value to improve our understanding about mechanism of plant water consumption and provide important basis of regional forest ecosystem management and maintenance, thus, laboratory controlled experiments were carried out to obtain Platycladus orientalis sapling foliar water use efficiency under five different soil water contents, including instantaneous water use efficiency (WUEgs) derived from gas exchange and short-term water use efficiency (WUEcp) caculated using carbon isotope model. The results showed that, controlled by stomatal conductance (gs), foliar net photosynthesis rate (Pn) and transpiration rate (Tr) increased as soil water content increased, which both reached maximum va-lues at soil water content of 70%-80% field capacity (FC), while WUEgs reached a maximum of 7.26 mmol·m-2·s-1 at the lowest soil water content (35%-45% FC). Both δ13C of water-soluble leaf and twig phloem material achieved maximum values at the lowest soil water content (35%-45% FC). Besides, δ13C values of leaf water-soluble compounds were significantly greater than that of phloem exudates, indicating that there was depletion in 13C in twig phloem compared with leaf water-soluble compounds and no obvious fractionation in the process of water-soluble material transportation from leaf to twig. Foliar WUEcp also reached a maximum of 7.26 mmol·m-2·s-1 at the lowest soil water content (35%-45% FC). There was some difference between foliar WUEgs and WUEcp under the same condition, and the average difference was 0.52 mmol·m-2·s-1. The WUEgs had great space-time variability, by contrast, WUEcp was more representative. It was concluded that P. orientalis sapling adapted to drought condition by increasing water use efficiency and decreasing physiological activity.