biostudies-literatureGarcia-Huidobro MRUniversidad Andrés BelloMINECONPCICONICYTMillenium Nucleus CenterFONDECYT7-15https://www.ebi.ac.uk/biostudies/studies/S-EPMC6439230biostudies-literatureUnknown9Biological interactions and environmental constraints alter life-history traits, modifying organismal performances. Trematode parasites often impact their hosts by inducing parasitic castration, frequently correlated with increased body size in the host (i.e., gigantism hypothesis), which is postulated to reflect the re-allocation of energy released by the reduction in the reproductive process. In this study, we compared the effect of a trematode species on shell size and morphology in adult individuals of the intertidal mussels <i>Perumytilus purpuratus</i> (>20 mm) collected from two local populations of contrasting environmental regimes experienced in central-southern Chile. Our field data indicates that in both study locations, parasitized mussels evidenced higher body sizes (shell lenInternational journal for parasitology. Parasites and wildlifeRole of temperature and carbonate system variability on a host-parasite system: Implications for the gigantism hypothesis.PMC6439230NC120086317052216-18/R1171056ACT172037Pulgar JAldana MLagos NALardies MAGarcia-Huidobro MRVaras OGeorge-Nascimento MfalseRole of temperature and carbonate system variability on a host-parasite system: Implications for the gigantism hypothesis.Biological interactions and environmental constraints alter life-history traits, modifying organismal performances. Trematode parasites often impact their hosts by inducing parasitic castration, frequently correlated with increased body size in the host (i.e., gigantism hypothesis), which is postulated to reflect the re-allocation of energy released by the reduction in the reproductive process. In this study, we compared the effect of a trematode species on shell size and morphology in adult individuals of the intertidal mussels <i>Perumytilus purpuratus</i> (>20 mm) collected from two local populations of contrasting environmental regimes experienced in central-southern Chile. Our field data indicates that in both study locations, parasitized mussels evidenced higher body sizes (shell len2019-01-01T00:00:00Z2019 Aug2025-04-06T16:50:35.403Z2019-06-06T21:03:44ZS-EPMC64392303097651110.1016/j.ijppaw.2019.03.016