A phylogenetic interpretation of nematode vulval variations

Over the last few years vulva development in nematodes has been used as a m odel system to study the evolution of developmental processes by carrying o ut cell lineage and cell ablation studies in various nematodes. Furthermore , a genetic and molecular analysis of vulva development has been initiated in Pristionchus pacificus. Evolutionary interpretation of these comparative developmental studies requires a phylogenetic understanding of nematodes. Recently, a molecular phylogeny for the phylum Nematoda has been published. Here, we place the comparative data of vulva development onto this phyloge ny of nematodes to infer the direction of evolutionary change.