Growth cycle of the marbled newt (Triturus marmoratus) in the mediterranean region assessed by skeletochronology

Abstract

We studied growth patterns within a marbled newt population (Triturus marmoratus, Urodela) at the southeastern limit of its geographical range by skeletochronology of the phalanges and humeri. Seasonal and annual changes in growth rates were assessed through the analyses of 56 females, 66 males and 34 juveniles sampled in different seasons and years. Age and growth cycles were estimated by cross sections of the diaphyseal region of the bone. These analyses revealed a clear line of metamorphosis caused by the metamorphic process itself and the transition to the terrestrial environment. A line of arrested growth (LAG) was observed in winter in both juveniles and adults. Another LAG was recorded in summer among adults. These growth patterns corroborated field observations on life-history traits of the population under study, but differ from those reported for the marbled newt in other environments.