An interesting Letter to Nature entitled “Effects of biodiversity on the functioning of trophic groups and ecosystem” here. A meta-analysis of studies that have “experimentally manipulated species diversity … shows that the average effect of decreasing species richness is to decrease the abundance or biomass of the focal trophic group, leading to less complete depletion of resources used by that group … (but also that) … the standing stock of, and resource depletion by, the most species-rich polyculture tends to be no different from that of the single most productive species used in an experiment.” Are there enough data out there for a similar meta-analysis of experimental manipulations of genetic diversity in crop fields?