The contribution of phenotypic plasticity to adaptation in Lacerta vivipara

Correlation between intraspecific phenotypic variability and variation of e nvironmental conditions could reflect adaptation. Different phenotypes may result from differential expression of a genotype in different environments (phenotypic plasticity) or from expression of different genotypes (genetic diversity). Populations of Lacerta vivipara exhibit larger adult body leng th, lower age at maturity, higher fecundity, and smaller neonatal size in h umid habitats compared to dry habitats. We conducted reciprocal transplants of juvenile L. vivipara to test for the genetic or plastic origin of this variation. We captured gravid females from four populations that differed i n the relative humidity of their habitats, and during the last 2 to 4 weeks of gestation, we manipulated heat and water availability under laboratory conditions. Juveniles were released into the different populations and fami lies were divided to compare growth rate and survival of half-sibs in two e nvironments. Growth rate and survival were assessed using capture-recapture techniques. Growth rate was plastic in response to postnatal. conditions a nd did not differ between populations of origin. Survival differed between populations of origin, partially because of differences in neonatal body le ngth. The response of juvenile body length and body condition to selection in the different habitats was affected by the population of origin. This re sult cannot be simply interpreted in terms of adaptation; however, phenotyp ic plasticity of fecundity or juvenile size most probably resulted in adapt ive reproductive strategies. Adaptation to the habitat by means of genetic specialization was not detected. Further investigation is needed to discrim inate between genetic and long-term maternal effects.