How evolution draws trade-offs

Recent empirical evidence suggest that tradeoff shapes can evolve, challenging the classica image of their high entrenchment. Here we model the evolution of the physiological mechanism that controls the allocation of resources to two traits, by mutating the expression and the conformation of its constitutive hormones and receptors. We show that trade-off shapes do indeed evolve in this model through the combined action of genetic drift and selection, such that their evolutionarily expected curvature and length depend on context. Despite this convergence at the phenotypic level, we show that a variety of physiological mechanisms may evolve in similar simulations, suggesting redundancy at the genetic level. We anticipate that more complex evolutionary scenarios should tighten this link between genotype and phenotype. This model should provide a useful framework to interpret the overly complex observations of both evolutionary endocrinology and evolutionary ecology.