HIGH GENETIC-VARIABILITY IN INSULAR POPULATIONS OF THE LACERTID LIZARD, PODARCIS-MURALIS

Allozyme electrophoresis was used to study genetic variability in Ital ian insular populations of the ecologically variable lizard Podarcis m uralis. To test the theory predicting more genetic variation in mainla nd than in island populations, polymorphism and heterozygosity also we re estimated in mainland populations of P. muralis from Italy, Spain a nd Austria. The results of this investigation showed that levels of ge netic variability in insular populations were significantly higher tha n those in mainland populations. This is probably because the insular populations inhabit marginal environments characterized by temporal-ec ological instability. in these environments high heterozygosity levels can be preserved after colonization events, unless founder population s are so small that bottleneck effects occur. (C) 1997 Elsevier Scienc e Ltd.