##### The "Data" folder contains the following CSV/text files:

1. trout_metabolism.csv, where the 'fish' column indicates which source stream the fish was collected from, 'mass' is the wet weight of the fish in g, 'temp' is the average temperature during the experiment in °C, and 'resp' is the oxygen consumption (respiration) rate in mg O2 h^-1.

2. trout_feeding.csv, where the 'fish' column indicates which source stream the fish was collected from, 'prey' indicates whether the prey species used in the experiment was the snail Radix balthica or blackfly larvae from the Simuliidae family, 'mass' is the wet weight of the fish in g, 'temp' is the average temperature during the experiment in °C, and 'feeding' is the feeding rate in individuals h^-1.

3.trout_genetics.txt, corresponding to a genepop format file (here in plain text format) used for population genetic analyses, characterised by a header line ("Title line"), a list of 17 microsattelie marker loci (mk1, mk2, etc.), population separators ("Pop"), and individual genotypes (e.g., 131140, indicating that individual is heterozygous for the 131 and 140 alleles at that locus). Rows correspond to individual fish, and columns to diploid genotypes (in 3 digit allele format). First pop = Stream IS1, Second pop = Stream IS5, Third pop = Stream IS12. Microsatellite markers arranged in same order as listed in Supplementary Table 9 in the O'Gorman et al. Communications Biology paper Brown trout (Salmo trutta) originating from warmer streams in Iceland exhibit increased energetic efficiency".

##### The "Code" folder contains R scripts for analysing the data as illustrated in the O'Gorman et al. Communications Biology paper Brown trout (Salmo trutta) originating from warmer streams in Iceland exhibit increased energetic efficiency".