Dear reader, The aim of this file is to introduce the files and the variables in the files that were used in the data analyses of the paper “Costs and benefits of polyandry in a placental poeciliid fish Heterandria formosa are in accordance with the parent-offspring conflict theory of placentation” by Ala-Honkola et al. (Journal of Evolutionary biology). Polyandry experiment, male behaviour in data file male_behaviour_polyandry.txt. male = male id, rep = replicate, trt = treatment (1= single-male trt, 2 = 2-male trt, 3 = 4-male trt), msl = male standard length, totkyt = total time spent following (s), totpar = total number of copulations and copulation attempts. Polyandry experiment, offspring standard length at birth in data file polyandry_sl_at_birth.txt. replicate = replicate, female_id = female id, femaleSL = female standard length at the beginning of the experiment, trt = treatment (1= single-male trt, 2 = 2-male trt, 3 = 4-male trt), offspring = the number refers to the order in which offspring were born (i.e. 1 is the first offspring of the given female), birthdate = date the given offspring was born, days_since_beginning = the time it took from the beginning of the experiment for the given offspring to be born, SL = offspring standard length at birth, clutchnro =tells which clutch of a given female is in question, clutchsize = tells how many offspring there were in the given clutch, alivesexedor19weeks = tells whether the given offspring was alive at maturity or at 19 weeks of age (1 = yes, 0 = no), dadid = sire identity, mindad = minimum number or sires for the given female, maxdad = maximum number or sires for the given female, dadorder = the mating order of the male who sired the offspring, alive = 1; offspring was born live; 0; offspring was born dead. Polyandry experiment, age and size at maturity for male offspring in data file polyandry_male_offspring.txt. See explanations for the first variables above (same as in data file polyandry_sl_at_birth.txt), sex = sex of the offspring(m equals male), maturitydate = date the given male was mature, SLmaturity = standard length at maturity, age_at_maturity= age (days) at maturity. Polyandry experiment, age and size at maturity for female offspring in data file polyandry_female_offspring.txt. See explanations for the variables above (same as in data files polyandry_sl_at_birth.txt and polyandry_male_offspring.txt). Polyandry experiment, number of offspring produced, proportion of dead-borne offspring and time until first birth can be found in data file polyandry_number_of_offspring_produced.txt. replicate = replicate, trt = treatment (1= single-male trt, 2 = 2-male trt, 3 = 4-male trt), female_id = female id, femaleSL = female standard length at the beginning of the experiment, offspring_produced = number of offspring produced during the experiment, first_clutch_size = number of offspring in the first clutch, time_until_first_offspring_was_born = the time it took from the beginning of the experiment for the given female’s offspring to be born , number_of_clutches = the number of clutches produced. Brood relatedness experiment, offspring sizes at birth in data file Brood_relatedness_offspring_sizes.txt Female = female id, StartDate = start date of the experiment, EndDate = end date of the experiment, FemaleTL = Female standard length at the beginning of the experiment, EndTL = Female standard length at the end of the experiment, Family = family from which the female originated from, Offspring = The number refers to the order in which offspring were born (i.e. 1 is the first offspring of the given female), BirthDate = date the given offspring was born, Treatment: Related means males were brothers, Unrelated means males were unrelated to each other, daystobirth = the time it took from the beginning of the experiment for the given offspring to be born, SLength = standard length of the offspring (i.e. length without the tail fin), Fathers = number of sires in given females offspring (minimum number). Brood relatedness experiment, female survival data in data file Brood_relatedness_survival_analysis.txt Offspring production parameters were calculated from the same data set but females from family 79 were left out as one of those females did not produce any offspring. naaras = female id, fam = family from which the female originated from, SL = Female standard length at the beginning of the experiment, trt = treatment; related means males were brothers, unrelated means males were unrelated to each other, Startdate = start date of the experiment, babyN = number of offspring born for the given female, firstbaby = days it took from the beginning of the exp. for the 1st offspring to be born, lastbababy = days it took from the beginning of the exp. for the last offspring to be born, livebaby = number of live-born offspring, deadbaby = number of dead-born offspring, deaddate = date the given female died, longevity= days a given female lived since the beginning of the experiment, censor = censor used in the survival analysis (1 = dead date known, 0 = survived until the given date). Please do not hesitate to contact me if you wish to get further clarifications. Sincerely, Outi Ala-Honkola outi.alahonkola@gmail.com