title: Probabilistic maturation reaction norms assessed from mark-recaptures of wild fish in their natural habitat.
abstract: Reaction norms are a valuable tool in evolutionary biology. Lately, the probabilistic maturation reaction norm approach, describing probabilities of maturing at combinations of age and body size, has been much applied for testing whether phenotypic changes in exploited populations of fish are mainly plastic or involving an evolutionary component. However, due to typical field data limitations, with imperfect knowledge about individual life histories, this demographic method still needs to be assessed. Using 13 years of direct mark-recapture observations on individual growth and maturation in an intensively sampled population of brown trout (Salmo trutta), we show that the probabilistic maturation reaction norm approach may perform well even if the assumption of equal survival of juvenile and maturing fish does not hold. Earlier studies have pointed out that growth effects may confound the interpretation of shifts in maturation reaction norms, because this method in its basic form deals with body size rather than growth. In our case, however, we found that juvenile body size, rather than annual growth, was more strongly associated with maturation. Viewed against earlier studies, our results also underscore the challenges of generalizing life-history patterns among species and populations.
authors: Institute of Marine Research Flødevigen N-4817, His, Norway ; Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo P.O. Box 1066, Blindern, N-0316, Oslo, Norway ; Department of Natural Sciences, University of Agder P.O. Box 422, N-4604, Kristiansand, Norway.
authors: Esben M
authors: EM
authors: Olsen
authors: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo P.O. Box 1066, Blindern, N-0316, Oslo, Norway.
authors: Dimitar
authors: D
authors: Serbezov
authors: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo P.O. Box 1066, Blindern, N-0316, Oslo, Norway.
authors: Leif A
authors: LA
authors: Vøllestad
keywords: Age and size at maturation; Salmo trutta; Survival; growth; life-history evolution; phenotypic plasticity