Field ecology of Caenorhabditis species The findings of Félix and Duveau [4] demonstrate the new kind of science that can now be done with C. elegans and C. briggsae. Being able to return to a site and reliably resample nematodes makes long-term studies of nematode population genetics possible. The emerging next genera tion technologies for rapid sequencing of small genomes (the C. elegans genome is only 100 Mb) will facilitate complete genetic analysis of individuals and popu lations [6], permit tracking of polymorphisms through space and time, and help reveal the selective pressures on the whole genome; this will allow measurement of the rates of migration between local populations, permit quantification of the relative rates of outcrossing and selfing, and thus reveal the population genetic structure of C. elegans in detail. Similar ecosystems can be surveyed worldwide to identify parallel study sites, and the effects of climate and isolation by distance can be examined. Experimental interventions - for example, introduction of genetically tagged nematodes or manipulation of the ecosystem by selective removal of one class of transport host - are possible in these mesocosm-scale environments. Metagenomic surveys will reveal the interacting populations of microbes cohabiting with the nematodes, and isolate cultures can be tested for positive and negative interactions with nematode genotypes found on the same fruit or isolated elsewhere, revealing genotypic interactions between co-adapted nematode
and pathogen genomes. The findings presented by Félix and Duveau may represent the vanguard of a new generation of C. elegans researchers: you may find teams of Caenorhabditis-ologists paying remarkably close atten tion to rotting fruit in an orchard near you this summer