(A) Comparative lin-3 RNAi effect on vulva induction in C. elegans, C. briggsae and C. remanei. Tables show graphically the observed defects in vulval cell fate pattern after scoring at least 100 nematodes. Every column is a distinct Pn.p cell (3 to 8) and 1° fate is depicted in blue, 2° fate is depicted in red and 3° fate in yellow. Half fates represent cases where the Pn.p daughter cells adopt different cell fates after the first cell division. The defects are ordered based on their consequence on vulval induction index, from high index to low. (B) Treatment with the MEK inhibitor U0126 decreases vulval induction in C. elegans (n = 15 for DMSO control and 10 μM U0126 treatment), C. angaria (n = 32 for control, n = 27 for 150 μM U0126 treatment) and C. afra (n = 100 for control, n = 30 for 150 μM treatment), as measured by the vulval induction index (average number of induced Pn.p cells at the population, wild-type index = 3). In all cases P<0.0001 with a Mann Whitney test.