MEC-2/Stomatin is required for aversive behaviour but dispensable for prey detection in the predatory nematode Pristionchus pacificus

Sensory systems provide animals with essential information about their environment and are critical for generating appropriate behaviours. Mechanosensation is a fundamental component of this sensory repertoire, and disruption of mechanosensory pathways can have severe functional consequences. In the nematode Caenorhabditis elegans, mechanosensory circuits have been extensively characterized and mediate touch-driven navigation and avoidance. These circuits rely on conserved molecular components including the stomatin-like protein MEC-2 along with MEC-6, which function together in the mechanotransduction complex. In contrast, the predatory nematode Pristionchus pacificus has repurposed mechanosensory pathways to also enable prey detection, a derived ecological behaviour. As we previously demonstrated that Ppa-mec-6 is required for efficient predation, here we assessed if Ppa-mec-2 plays a similar role in P. pacificus prey detection. We find that while Ppa-mec-2 is required for the aversive touch response, it is dispensable for prey detection. This functional divergence reflects differential neuronal expression as Ppa-mec-2 is absent from the IL2 neurons that mediate prey detection and also robustly express Ppa-mec-6. These findings reveal that partitioning of mechanosensory components across neuronal types enables functional specialization, demonstrating how conserved sensory machinery can support distinct behavioural functions across evolution.