The physiological costs of prey switching reinforce foraging specialization

Sympatric speciation is thought to be strongly linked to resource specialization with alternative resource use acting as a fundamental agent driving divergence. However, sympatric speciation through niche expansion is dependent on foraging specialization being consistent over space and time.
Standard metabolic rate is the minimal maintenance metabolic rate of an ectotherm in a post-absorptive and inactive state and can constitute a significant portion of an animal's energy budget; thus standard metabolic rate and growth rate are two measures frequently used as an indication of the physiological performance of individuals. Physiological adaptations to a specific diet may increase the efficiency with which it is utilized, but may have an increased cost associated with switching diets, which may result in a reduced SMR and growth rate.
In this study we use the diet specialization often seen in polymorphic Arctic charr (Salvelinus alpinus) populations to study the effects of different pre...