Phenotypic plasticity tends to increase in temporally and spatially variable environments. This thesis deals with the variability of life-history traits in fragmented populations. In Mediterranean regions, Parsley frog, Pelodytes punctatus, breeds both in spring and in autumn, in response to temporal variations of its environment. I studied the origin and evolutionary consequences of its breeding strategies.
Both breedin periods producs offspring (much more in autumn though) and spring tadpoles suffer from intraspecific competition with older autumn tadpoles. Autumn laid juveniles are buigger and emerged sooner from the ponds. These developmental differences are not due to genetic differences betwenn seasonal populations. They are explained by phenotypic plasticity in response to drastically different conditions. Even if it seems more favourable to breed in autumn, both strategies are maintained either by bet-hedging or pure opportunism.
Besides, fragmentation, which increases with global changes, tends to reduce population effective size and increase genetic heterogeneity within populations. However, no inbreeding was found in the studied populations bu a high family structure induced allele/fitness correaltions.
Together these results enlighten the variability of breeding strategies and larval traits in Parsley frog and indicate a high phenotypic plasticity in response to environmental variations.