Turnover of plant lineages shapes herbivore phylogenetic beta diversity along ecological gradients

Understanding drivers of biodiversity patterns is of prime importance in this era of severe environmental crisis. More diverse plant communities have been postulated to represent a larger functional trait‐space, more likely to sustain a diverse assembly of herbivore species. Here, we expand this hypothesis to integrate environmental, functional and phylogenetic variation of plant communities as factors explaining the diversity of lepidopteran assemblages along elevation gradients in the Swiss Western Alps. According to expectations, we found that the association between butterflies and their host plants is highly phylogenetically structured. Multiple regression analyses showed the combined effect of climate, functional traits and phylogenetic diversity in structuring butterfly communities. Furthermore, we provide the first evidence that plant phylogenetic beta diversity is the major driver explaining butterfly phylogenetic beta diversity. Along ecological gradients, the bottom up control of herbivore diversity is thus driven by phylogenetically structured turnover of plant traits as well as environmental variables.     

Crystallographic study of the complex between sulfite and bakers' yeast flavocytochrome b2

The complex between Saccharomyces cerevisiae flavocytochrome b2 and the sulfite anion has been analyzed by x-ray diffraction. A map of the difference in electron density between the complex and the native protein has been computed. One positive peak of electron density is visible at the active site of each of the two subunits in the asymmetric unit, very close to the N-5 of the flavin. The molecular fragment SO3(2-) can account for the shape of this difference in electron density. A third peak is visible in the subunit containing pyruvate, the reaction product. It is a peak of negative electron density localized at the position where the pyruvate usually is in the native form. These results are interpreted on the basis of the mechanism defined in solution for the reaction between flavins and sulfite.