Life history of Vipera ursinii ursinii at Mont-Ventoux France Strategie demographique de Vipera ursinii ursinii au Mont-Ventoux France
Baron, J.-Pierre.; Ferriere, R.; Clobert, J.; Saint Girons, H.
Comptes Rendus de l'Academie des Sciences Serie III Sciences de la Vie. Janvier; 3191: 57-69
The life history of Vipera ursinii ursinii at Mont-Ventoux (France) is documented on the basis of mark-recapture data collected on a long-term field study (1979-1991). Traits under consideration relate to the individual growth, survival and reproduction of the snakes. Demographic variations (i.e., among individuals), temporal variations (across years) and spatial variations (between 2 distinct patches of habitat) in the traits are analyzed, as well as phenotypic correlations. In doing so, we get insights into the phenotypic plasticity of V. ursinii and the determinants of reproductive effort in this species. Plasticity is demonstrated in individual growth (spatially variable), parturition date and litter size (temporal variations), and offspring mass (temporal and demographic variations). Spatial variations in individual growth and temporal fluctuations in parturition date might be driven by exogenous factors (local humidity and duration of sunny conditions in summer, respectively). Litter size (corrected for maternal body size) and neonate mass vary across years. Controlling for this time effect, litter size and neonate mass ap ear to be negatively corre ted. suggest that neonate mass might be subject to endogenous factors, e.g. female mating success if sperm competition occurs-with yearly fluctuations in litter size that would result as a by-product of a physiological trade-off with neonate mass. Litter size varies less amongst individuals than throughout a female's lifespan, whereas offspring mass vary more among litters than within a given litter. Finally, survival probabilities (that depend on age), reproductive frequency (dominated by a biennial cycle), relative clutch mass (that usually increases with maternal size) and litter sex ratio seem to be strongly canalized. Reproductive effort is assessed by the relative clutch mass, which tightly correlates with postpartum body condition. Except in one year, relative clutch mass increases with body size.