The symbolic value of grafting in ancient Rome

Some scholars have read Virgil’s grafted tree (G. 2.78–82) as a sinister image, symptomatic of man’s perversion of nature. However, when it is placed within the long tradition of Roman accounts of grafting (in both prose and verse), it seems to reinforce a consistently positive view of the technique, its results, and its possibilities. Virgil’s treatment does represent a significant change from Republican to Imperial literature, whereby grafting went from mundane reality to utopian fantasy. This is reflected in responses to Virgil from Ovid, Columella, Calpurnius, Pliny the Elder, and Palladius (with Republican context from Cato, Varro, and Lucretius), and even in the postclassical transformation of Virgil’s biography into a magical folktale.

MFN status and the choice of tariff regime

The gradualist approach to trade liberalization views the uniform tariffs implied by MFN status as an important step on the path to free trade. We investigate whether a regime of uniform tariffs will be preferable to discriminatory tariffs when countries engage in non-cooperative interaction in multilateral trade. The analysis includes product differentiation and asymmetric costs. We show that with the cost asymmetry the countries will disagree on the choice of tariff regime. When the choice of import tariffs and export subsidies is made sequentially the uniform tariff regime may not be sustainable, because of an incentive to deviate to a discriminatory regime. Hence, an international body is needed to ensure compliance with tariff agreement.

A regime view of the North Atlantic Oscillation and its response to anthropogenic forcing

The distribution of the daily wintertime North Atlantic Oscillation (NAO) index in the 40-yr ECMWF Re-Analysis (ERA-40) is significantly negatively skewed. Dynamical and statistical analyses both suggest that this skewness reflects the presence of two distinct regimes—referred to as “Greenland blocking” and “subpolar jet.” Changes in both the relative occurrence and in the structure of the regimes are shown to contribute to the long-term NAO trend over the ERA-40 period. This is contrasted with the simulation of the NAO in 100-yr control and doubled CO2 integrations of the third climate configuration of the Met Office Unified Model (HadCM3). The model has clear deficiencies in its simulation of the NAO in the control run, so its predictions of future behavior must be treated with caution. However, the subpolar jet regime does become more dominant under anthropogenic forcing and, while this change is small it is clearly statistically significant and does represent a real change in the nature of NAO variability in the model.

An ancient pollinator of a contemporary plant (Cyclamen persicum): When pollination syndromes break down

Pollination of Cyclamen persicum (Primulaceae) was studied in two wild populations in Israel. Buzz-pollination proved to be extremely rare, and performed by a large Anthophora bee only. The most frequent pollinators were various unspecialized species of thrips (Thysanoptera) and hoverflies (Syrphidae). In the Winter-flowering populations the commonest visitor was a small primitive moth, Micropteris elegans (Micropterigidae, Lepidoptera). These moths feed on pollen, copulate and oviposit within the flowers. From the rarity of buzz-pollination it is concluded that the genus Cyclamen co-evolved with large bees capable of buzz-pollination, but lost its original pollinators for unknown historical reasons. The vacant niche was then open to various unspecialized pollen consumers such as thrips, hoverflies and small solitary bees. While these insects are not specific to C. persicum and seem to play a minor role only, the moth strictly relies upon Cyclamen and seems to be the most efficient pollinator.