title: Larval life history and anti-predator strategies are affected by breeding phenology in an amphibian.
abstract: Seasonal time constraints can pose strong selection on life histories. Time-constrained animals should prioritise fast development over predation risk to avoid unfavourable growing conditions. However, changes in phenology could alter the balance between anti-predator and developmental needs. We studied variation of anti-predator strategies in common frog (Rana temporaria) tadpoles in four populations from the two extremes of a latitudinal gradient across Sweden. We examined, under common conditions in the laboratory, the anti-predator responses and life histories of tadpoles raised with predatory Aeshna dragonfly larvae in two consecutive years with a difference of 20 days in breeding time in the north, but no difference in breeding time in the nouth. In a year with late breeding, northern tadpoles did not modify their behaviour and morphology in the presence of predators, and metamorphosed faster and smaller than tadpoles born in a year with early breeding. In the year with early breeding, northern tadpoles showed a completely different anti-predator strategy by reducing activity and developing morphological defences in the presence of predators. We discuss the possible mechanisms that could activate these responses (likely a form of environmentally-mediated parental effect). To our knowledge, this is the first study to show that a vertebrate modifies the anti-predator strategy of its offspring in response to natural variation in reproductive phenology, which highlights the need to consider phenology in studies of life-history evolution.
authors.affiliation: Population and Conservation Biology/Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden. german.orizaola@ebc.uu.se
authors.forename: Germán
authors.initials: G
authors.lastname: Orizaola
authors.forename: Emma
authors.initials: E
authors.lastname: Dahl
authors.forename: Alfredo G
authors.initials: AG
authors.lastname: Nicieza
authors.forename: Anssi
authors.initials: A
authors.lastname: Laurila
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D007313:Insecta / Q000502:physiology; D007814:Larva / Q000502:physiology; D008675:Metamorphosis, Biological / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D019370:Observation; D011235:Predatory Behavior / Q000502:physiology; D011896:Rana temporaria / Q000502:physiology*; D012621:Seasons; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013548:Sweden; D013997:Time Factors