General description: This README file accompanies the data file "IoM_mousedata_dietandimmunity.csv". The data file contains data associated with the publication Taylor et al. 2019 "Immune state is associated with natural dietary variation in wild mice Mus musculus domesticus" Functional Ecology. Data collection: Data refer to 74 individual mice Mus musculus domesticus that were trapped on the Isle of May, Scotland on 9th-12th October 2015. For full details of methodology, please refer to the above publication. Missing data are indicated by NA. Variable descriptions: id: individual reference number Date: date of capture dd/mm/yyyy Location: code for sampling location (see paper for key to codes) Trap: code for trap, consisting of Location code followed by trap number GPS_lat: latitude GPS_long: longitude d13C: delta-13 carbon values in per mil d15N: delta-15 nitrogen values in per mil PuffinBurrows: number of puffin burrows in that region of the island, taken from Newell et al 2017 census. PuffinDensity: PuffinBurrows divided by the area (in hectares) of the relevant island region Vegetation: dominant vegetation at that trapping location, either "Holcus" (lanatus) or "Silene" (uniflora). Taken from a vegetation survey by Rene van der Waal (unpublished data) Sex: F (female) or M (male) determined by inspection of genitalia Weight_total: mass in grams, measured immediately after euthanasia Weight_eye_lens: total dry mass of both eye lenses in mg Length_SV: length from snout to vent, in mm Age_days: estimated age in days, calculated from eye lens weight using the method described by Rowe et al. 1985. Syphacia: count of adult and juvenile Syphacia obvelata from whole-gut dissection Trichuris: count of adult and juvenile Trichuris muris from whole-gut dissection spleen_FoxP3: concentration of FoxP3 mRNA measured from spleen tissue, given as a ratio against reference genes Sdha and Ubc using the 2^(-delta delta CT) method. spleen_GATA3 to spleen_TNFa: as above, for different genes MLN_IL1B to MLN_Irf5: as above, for a range of genes measured from the mesenteric lymph nodes IL1b: concentration of IL1b protein measured from blood, in pg ml^-1 IL5 to Leptin: as above, for different proteins