PHENOTYPIC PLASTICITY OF GROWTH AND SURVIVAL IN THE COMMON LIZARD LACERTA-VIVIPARA

1. In this study we investigated sources of variation in growth rate a nd survival in the common lizard Lacerta vivipara. 2. We conducted two experiments to identify factors that explain the pattern of geographi c variation of life-history traits in this species. In the first exper iment, we raised hatchlings from two French populations of L. vivipara , located at low (150 m) and high (1400 m) altitudes, under identical laboratory conditions. The hatchlings grew at the same rate when exper iencing the same environmental conditions irrespective of their origin . This finding suggests that the observed differences in growth rate b etween these two populations of L. vivipara are driven by environmenta l factors (e.g. thermal environment) rather than genetic divergence. A lthough we did not find any genetic difference between populations, we found some evidence of within-population variation in growth rate. 3. In a second experiment, we raised hatchlings from the high altitude p opulation in outdoor enclosures located at low and high altitudes. The site where hatchlings were raised had a large impact on both growth a nd survival. Lizards located in the low altitude site grew faster and had a higher mortality rate than lizards located in the high altitude site. These findings are consistent with the observed differences in g rowth and survival between the natural populations inhabiting the two localities, 4. In spite of the low statistical power of the models use d to detect the family x environment interactions, we found a marginal ly significant interaction for survival (P = 0.054), which suggests th at phenotypic plasticity of this trait may have some degree of genetic variance. 5. Finally, we did not find any evidence for a genetic corr elation between growth and survival in the high altitude population. T his suggests that the observed phenotypic trade-off between the two tr aits may arise from environmental constraints (e.g. more active lizard s have higher growth rates but also have higher risks of predation). 6 . Overall, our findings emphasize that environmental factors may play a major role in shaping patterns of life-history association in L. viv ipara, and in explaining geographic variation of life histories.