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

Abstract 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.