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11.
Parent–offspring conflict theory predicts the evolution of offspring solicitation signals that can influence the amount and/or
the duration of parental investment. Short-term effects of offspring solicitation signals on parental food provisioning have
been widely demonstrated, but persistent effects of offspring signals on the maintenance of parental care have been rarely
studied. Also, the relation between the amount of care provided to the brood and how it is distributed among individual offspring
within a brood is not well enough understood. Here, we investigated in the European earwig (Forficula auricularia) the effects of offspring condition-dependent chemical signals on the maintenance of maternal care among broods and the distribution
of maternal food within broods. Mothers were isolated from their brood for 3 days and continuously exposed to chemical signals
extracted from broods of experimentally manipulated nutritional state. After re-introducing mothers to their brood, a range
of maternal behaviours were quantified. We found that earwig mothers groomed their offspring significantly more after exposure
to chemical extract from high-food brood in comparison with mothers exposed to extract from low-food brood, which in turn
displayed significantly more aggressive behaviour. Furthermore, we manipulated offspring individual nutritional condition
within the brood to evaluate the effect of offspring state on the within-brood food distribution. Within broods, poorly fed
individuals received significantly more food than well-fed individuals, probably due to scramble competition. These results
show that earwig nymphs express multi-component condition-dependent signals and behaviours differentially affecting maternal
care provisioned to the brood and the distribution of care within broods. 相似文献
12.
Reactivity of the plant growth regulator paclobutrazol (cultar) with two tropical soils of the northeast semiarid region of Brazil 总被引:1,自引:0,他引:1
Milfont ML Martins JM Antonino AC Gouveia ER Netto AM Guiné V Mas H dos Santos Freire MB 《Journal of environmental quality》2008,37(1):90-97
The reactivity of paclobutrazol (PBZ, a plant growth retardant) with a Yellow Ultisol and a Vertisol from the semiarid northeast region of Brazil was evaluated through batch sorption experiments and modeling. Although not instantaneous, the sorption kinetic of PBZ (pure and formulated) was fast (a few hours) in both soils. The sorption kinetics were well described by a second-order (dS(t)/dt=k(2)(S(e2)-S(t))(2)) but not by a first-order model. The sorption isotherms were found to be linear and the calculated K(D) values were 8.8 +/- 0.11 and 7.4 +/- 0.2 L kg(-1) for pure PBZ in the Ultisol and the Vertisol, respectively. The corresponding K(OC) values were 1275 +/- 34 (logK(OC) = 3.11) and 1156 +/- 49 (logK(OC) = 3.06) L kg(-1), respectively. Considering the very different texture of the two soils and the similar K(OC) values determined, these results showed that in both soils, the sorption of PBZ is dominantly controlled by organic matter, although some interactions of PBZ with iron oxides (goethite) were observed in the Ultisol. Based on these sorption parameters a low leachability potential of PBZ in soils is anticipated, as they correspond to a groundwater ubiquity score (GUS) ranging from 2.0 to 2.7, i.e., moderately to not mobile, in contradiction with the actual groundwater situation in Brazil. This work stresses the need to evaluate and predict the risk associated with aquifer contamination by this widely used plant growth regulator. 相似文献