SalmoScales

Species radiations can be driven by changes in body proportions (allometric changes), that is, natural selection acting on size and not in shape. Discovering the genetic and developmental basis of allometry has both fundamental importance for understanding the emergence of biological diversity, as well as in practical terms such as in understanding cancers. Only a few allometry mechanisms are known to explain adaptive differences in organ size within a vertebrate species. The SalmoScales project will fill this knowledge gap by discovering the molecular, developmental, and evolutionary mechanisms that give rise to allometry of reproductive organs in Atlantic salmon (Salmo salar). Salmon show a fascinating adaptation of organ allometry associated with a trade-off in life history strategies; dwarf landlocked ecotypes prioritize egg size over egg number, and in consequence have ovaries that are 50% smaller compared to their sea-migrating congeners. The decreased ovary size in dwarf salmon provides a unique model to study how allometry emerges within a single species and interplays with life history strategy. Salmon reproductive development is governed by transcriptional regulators that include the genes vgll3 and six6. These genes are top candidates for mediating ovary allometry as my preliminary results suggest that vgll3 interacts with Hippo signaling pathway mediating organ size, as well as transcription factors controlling for germ cell development in salmon gonads. I will dissect the genotype-phenotype-fitness map of ovary allometry from the molecular to the species level with an integrative approach combining cellular genomics, gene editing, and a powerful quantitative genetics framework. The results will have applied significance in aquaculture to inform precision breeding for egg, brood and maturation characteristics, as well as in the medical field, where revealing the mechanisms that coordinate ovary growth and size are important to understand ovarian cancers.

2023

2026