Contact-based kin discrimination is associated with specific surface lipids in the cannibalistic nematode Pristionchus pacificus

Abstract Kin-recognition is widespread, yet its molecular basis remains poorly understood. In the predatory nematode Pristionchus pacificus , kin-recognition prevents cannibalism of close relatives and depends on the peptide SELF-1. Here, we show this behavior is robust to environmental stress but disrupted by a surfactant wash, implicating lipids or other amphiphilic molecules as necessary components for this mechanism. Using 3D-OrbiSIMS, we profiled the outer cuticle of kin-recognition defective self-1 mutants and found these animals exhibit distinct surface lipids. Furthermore, analysis of surface chemistry defective daf-22 mutants alongside self-1;daf-22 double mutants revealed additional, non-overlapping surface lipid profiles, indicating that multiple pathways contribute to shaping surface lipid composition. Importantly, by combining automated behavioral tracking with state-based analysis, we show daf-22 mutants are also kin-recognition defective. Together, these findings demonstrate that the composition of the nematode surface is required to maintain kin identity, with the cuticle acting as a signaling interface that regulates contact-dependent behaviors. Teaser (125 characters) Surface lipid composition correlates with nematode kin-recognition signaling abilities.