Age, size, and growth of the alpine newt, Triturus alpestris (Urodela : Salamandridae), at high altitude and a review of life-history trait variationthroughout its range

We studied a population of the alpine newt, Triturus alpestris, living at t he upper limit of its altitudinal range (2200 m in the northwestern Alps) d uring the aquatic activity period. Age was estimated by skeletochronology a pplied to phalanges and body size was measured. Age structures were similar between sexes, with age at maturity at 9-11 years and longevity up to 20 y ears. Annual survival was 0.81. Females were significantly larger than male s. Growth, modelled according to van Bertalanffy's growth model, was higher in females during the juvenile period. A comparative analysis of age and s ize at maturity, mean size, and longevity in several European populations d istributed from sea level to high altitudes shows a significant increase in these phenotypic variables with the decrease of the duration of the activi ty period. The growth coefficient IC indicating the shape of the curve, is smaller in highland than in lowland populations, and the asymptotic size is smaller in the plain than at higher altitude. If adult size increases with altitude, age at maturity is extensively delayed in short activity period environments. The discussion is focussed on the patterns of variation of th ese traits. However, age and size of newts can also depend on traits of the previous stages of the life cycle, and larval stages in response to enviro nmentalgradients.