POPULATION-GENETICS OF A COLONIZING LIZARD - LOSS OF VARIABILITY IN INTRODUCED POPULATIONS OF PODARCIS-SICULA

Allozyme electrophoresis was used to study the genetic variability (pr oportion of polymorphic loci and heterozygosity) in insular population s (Corsica, Elba, Montecristo, Marettimo, Pantelleria) of the lacertid lizard Podarcis sicula. These populations were presumed to have origi nated from episodes of accidental anthropogenic introduction. In order to test the hypothesis of a man-aided colonization and to provide com parative data, heterozygosity and polymorphism were also estimated in autochthonous populations of P. sicula from the Italian peninsula and Sicily. In each case, the presumed introduced population showed levels of genetic variability significantly lower than those detected in the autochthonous ones. Very little genetic differentiation was found amo ng native and presumed colonist populations, Nei's standard genetic di stances ranging from 0.001 to 0.009. These results strongly support th e hypothesis that P. sicula was only recently introduced to the studie d islands, and provide additional evidence of reduced genetic variabil ity due to founder effect in insular populations originating from epis odes of human transportation.