DOI: 10.5061/dryad.v65m0
title: Data from: The physiological costs of prey switching reinforce foraging specialization

description: 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 prey on
 standard metabolic rate and growth rate as well as the effects that early
 prey specialization may have on the ability to process other prey types
 efficiently. We found a significant effect of prey type on standard
 metabolic rate and growth rate. Furthermore, we found evidence of diet
 specialization with all fish maintaining a standard metabolic rate and
 growth rate lower than expected when fed on a diet different to which they
 were raised, possibly due to a maladaptation in digestion of alternative
 prey items. Our results show that early diet specialization may be
 reinforced by the elevated costs of prey switching thus promoting the
 process of resource specialization during the incipient stages of
 sympatric divergence.
description: ThePhysiologicalCostsOfPreySwitchingDATAThe data constitutes two stages. Stage 1 is growth data and standard metabolic rate (SMR) data recorded when fish were fed the diet on which they were raised and Stage 2 is growth and SMR data of fish being fed a diet different to the diet on which they were raised. This information is included in the fish ID. DP = Daphnia, BW = Bloodworm, GM = Gammarus. The first two initials represent the diet the fish were raised on, the second two initials represent the food the fish were being fed when the SMR and growth measurement were taken. STAGE 1, DPDP = SMR and growth data recorded when the fish raised on Daphnia were fed Daphnia, BWBW = SMR and growth data recorded when the fish raised on Bloodworm were fed Bloodworm, GMGM = SMR and growth data recorded when the fish raised on Gammarus were fed Gammarus. STAGE 2, DPBW = SMR and growth data recorded when the fish raised on Daphnia were being fed Bloodworm, DPGM = SMR and growth data recorded when the fish raised on Daphnia was being fed Gammarus, BWDP = SMR and growth data recorded when the fish raised on Bloodworm were fed Daphnia, BWGM = SMR and growth data recorded when the fish raised on Bloodworm were fed Gammarus, GMBW = SMR and growth data recorded when the fish raised on Gammarus were fed Bloodworm, GMDP = SMR and growth data recorded when the fish raised on Gammarus were fed Daphnia. The number at the end of the fish ID is to identify each individual. Start weight is the weight at the beginning of the growth trial and finish weight the weight of each fish at the end of the growth trial. SMR weight is the same as the finish weight of the growth trial because SMR was recorded immediately afterwards.