Résumé
Life-history variation within and among populations of widespread amphibian species has attracted much attention so far. In relation to a variety of problems (e.g. climate change, large-scale clines. conservation). this information is needed not only on broad geographic scale, but also at local level and front year to year. In this Study. we investigated variation in body size and life history traits, including age, fecundity and egg size, in two neighbouring populations of a widespread amphibian, the Common Toad Bufo bufa. during a 3-year period. Body size varied significantly between populations in males only but not between years. Age was assessed by skeletochronology, and osteometrical analyses revealed a complete endosteal resorption of the first line of arrested growth in 1.1 % of the individuals and a partial resorption in 77 % of tire individuals. Age structures did not differ significantly between sexes, populations, nor between years. Age at first reproduction was one year later in females than in males in both populations (4 vs 3 years), but adult survival rates did riot differ between sexes. Fecundity did not differ between Populations or years, but egg size varied between years. Fecundity increased with size, but not with age of females. This lack of significant interpopulation variation in age structure and reproductive traits is important for monitoring local populations which call be exposed to various potential disturbance factors. On the other hand, these results stress the importance of analysing temporal variation in life history traits because one-year data may not represent properly the reproductive features of a Population. and it, is issue is becoming more so important with the growing interest in climate changes and its possible effects (in amphibian Populations.