Description of variables sorting.number: fry identifier in entire dataset egg.number: egg identifier within units fert.date: date of fertilisation pop: source population family: family (female/male pair) identifier f.id: female ID m.id: male ID rep: replicate identifier - separator for the duplicates (a or b) treat: temperature treatment (low, medium or high) temp: temperature treatment in °C unit.ID: unit identifier (consist of population (H, L or O), treatment (L, M or H), status: successful hatching (1) or not (0) hatch.day: hatching day day degrees: day degrees until hatching