Genotype-specific variation in seasonal body condition at a large-effect maturation locus

Organisms use resource allocation strategies to survive seasonal environmental changes and life-history stage transitions. Earlier studies found a transcription cofactor, vgll3, associating with maturation timing that inhibits adipogenesis in mice and affects body condition in juvenile salmon. Owing to a lack of temporal studies examining seasonality effects on phenotypes such as vgll3 genotype, body condition, maturation and different life stages, we investigated the influence of different larval and juvenile temperatures, vgll3 genotype and interactions with body condition and maturation rate. We reared Atlantic salmon for 2 years in four larval-juvenile phase temperature groups until the occurrence of mature males. We found no effect of larval temperature on the measured phenotypes or maturation rate. However, we observed an increased maturation rate in individuals of the warm juvenile temperature treatment and differences in body condition associated with vgll3 genotype. Early maturation genotype individuals had a less variable body condition across seasons compared with late maturation genotype individuals. This result suggests a vgll3 influence on resource allocation strategies; possibly linked with the early maturation process, with early maturation genotype individuals having a higher maturation rate and a higher body condition in the spring.