Short- and Long-term Effects of High Temperatures (47–49 °C) on Tobacco Leaves. I. Photosynthesis

Detached Nicotiana rustica leaves were exposed for 2 minutes to temperatures in the range 36° to 51°C. Above 45°C, ¹⁴CO₂ fixation was reduced by half as compared with controls. The fall in ¹⁴CO₂ fixation continued for 2 1/2 h. Recovery was completed 45 h after the treatment. Above 45°C there was an increase in the labeled cationic and anionic fractions and a decrease in the neutral fractions, both increase and decrease being associated with the impaired CO₂ fixation. However, these changes in products were also demonstrated when leaves were exposed to the high temperature after labeling.     

On the evolutionary and ontogenetic origins of tool‐oriented behaviour in New Caledonian crows (Corvus moneduloides)

New Caledonian crows (Corvus moneduloides) are prolific tool users in captivity and in the wild, and have an inherited predisposition to express tool‐oriented behaviours. To further understand the evolution and development of tool use, we compared the development of object manipulation in New Caledonian crows and common ravens (Corvus corax), which do not routinely use tools. We found striking qualitative similarities in the ontogeny of tool‐oriented behaviour in New Caledonian crows and food‐caching behaviour in ravens. Given that the common ancestor of New Caledonian crows and ravens was almost certainly a caching species, we therefore propose that the basic action patterns for tool use in New Caledonian crows may have their evolutionary origins in caching behaviour. Noncombinatorial object manipulations had similar frequencies in the two species. However, frequencies of object combinations that are precursors to functional behaviour increased in New Caledonian crows and decreased in ravens throughout the study period, ending 6 weeks post‐fledging. These quantitative observations are consistent with the hypothesis that New Caledonian crows develop tool‐oriented behaviour because of an increased motivation to perform object combinations that facilitate the necessary learning. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 870–877.     

Reconstruction of fig wasp mating structure: how many mothers share a fig?

Abstract.  1. Fig wasps (Hymenoptera: Agaonidae) represent an important model system for studies of sex ratio evolution, mainly because they may adjust their sex ratios in response to the numbers of ovipositing females (foundresses) that enter a fig and their clutch size.
2. Until recently, it was assumed that all foundresses fail to re-emerge from the figs that they have entered to oviposit, but there is increasing evidence that such re-emergence may be routine. The common practice of counting the number of dead foundresses present in a fig in order to deduce the number of foundresses is therefore questionable in species where failure to re-emerge has not been confirmed.
3. In this study, the alternative approach of microsatellite markers was used to reconstruct the within-fig breeding structure of a pollinating fig wasp by genetic analysis of the offspring. Broods of Liporrhopalum tentacularis , a species where foundresses regularly re-emerge from figs, were collected from figs of Ficus montana in their natural habitat in Indonesia as well as from an experimental glasshouse population in Leeds (U.K.).
4. The estimated foundress densities in the glasshouse population were similar to those in the field and ranged from one to six foundresses per brood.
5. Nearly 40% of all broods were produced by a single foundress, indicating that mating in these broods occurs exclusively between full siblings. High levels of inbreeding are therefore common in this species.     

Fine-scale genetic structure and its consequence in breeding aggregations of a passerine bird

The pattern of fine-scale genetic structure in a population may reflect current biological processes of the species, such as natal dispersal, the breeding system and demography. We investigated the spatial distribution of nests and fine-scale genetic structure during two breeding seasons in a population of a weakly territorial, flock-living passerine bird, the vinous-throated parrotbill, Paradoxornis webbianus . Nest distribution was clustered. There were two peaks of egg laying within each breeding season, and spatial clustering of nests was more extreme during the second peak after controlling for breeding density. The patterns of genetic structure during the breeding season varied with parental sex and season. Genetic structure occurred during the second laying peak: males breeding within 200 m of one another at this time were significantly more closely related than males breeding farther apart. However, no apparent genetic structure was detected in males during the first laying peak or among females in either laying peak. These results reveal male-oriented kin affiliation during part of the breeding season in this species. Furthermore, juvenile recruitment into the winter flocks was positively related to this increased relatedness among males via kin affiliation. This study implies that fine-scale genetic structure during the breeding season could be a factor determining individual fitness and may play an important role in our understanding of the evolution of social systems.     

细胞生物学教学中的反思型教师教育

在分析了反思型教师教育兴起的背景后,作者在师范生《细胞生物学及实验》课程教学中,进行了两方面的反思性教学尝试：一方面实施对教学环节全过程的反思,另一方面是让学生参与教学实践。结果表明对师范生实施反思性教学,可以提高学生的反思能力,有利于师范生形成反思意识,养成初步的反思习惯,学生的反思能力显著提高。