Journal ArticleSocial Plasticity Enhances Signal-Preference CodivergenceDesjonquères, Camille; Speck, Bretta; Seidita, Sara; Cirino, Lauren A.; Escalante, Ignacio; Sergi, Clinton; Maliszewski, Jak; Wiese, Christine; Hoebel, Gerlinde; Bailey, Nathan W.; Rodríguez, Rafael L.The social environment is often the most dynamicandfitness-relevant environment animals experience. Here we testedwhether plasticity arising from variation in social environments canpromote signal-preference divergence—a key prediction of recentspeciation theory but one that has proven difficult to test in natural sys-tems. Interactions in mixed social aggregations could reduce, create,or enhance signal-preference differences. In the latter case, social plas-ticity could establish or increase assortative mating. We tested this byrearing two recently diverged species ofEnchenopatreehoppers—sap-feeding insects that communicate with plant-borne vibrationalsignals—in treatments consisting of mixed-species versus own-speciesaggregations. Social experience with heterospecifics (in the mixed-species treatment) resulted in enhanced signal-preference species dif-ferences. For one of the two species, we tested but found no differencesin the plastic response between sympatric and allopatric sites, sug-gesting the absence of reinforcement in the signals and preferencesand their plastic response. Our results support the hypothesis that so-cial plasticity can create or enhance signal-preference differences andthat this might occur in the absence of long-term selection against hy-bridization on plastic responses themselves. Such social plasticity mayfacilitate rapid bursts of diversification.The University of Chicago2023-12-0110507565The American Naturalist2026818 to 8290003-0147https://doi.org/10.1086/7267861855962indirect genetic effects, mating preference, courtship signal, Membracidae, vibrational communicationNational Science Foundation