COMPARATIVE ECOLOGY IN SYMPATRIC PODARCIS-MURALIS AND P-SICULA (REPTILIA, LACERTIDAE) FROM THE HISTORICAL CENTER OF ROME - WHAT ABOUT COMPETITION AND NICHE SEGREGATION IN AN URBAN HABITAT

Some aspects of comparative ecology in two sympatric Podarcis species, P. muralis and P. sicula, were studied in an urban park of Rome. Both species preyed on a wide variety of invertebrates, but mainly on inse cts. Food niche breadth was wider in P. muralis, and this is possibly related to the higher microhabitat heterogeneity of the species in the study area. Food niche overlap was relatively high. Activity patterns (annual cycle, daily activity) were rather similar in the two lacerti d lizards. Fecundity did not differ significantly between species, fem ale snout-vent length and clutch size being positively correlated. At least two clutches per year were detected in each species. In each of the two study sites chosen in the urban park the density of both speci es did not vary significantly amongst years. Podarcis muralis appeared to be the only species inhabiting humid places with dense vegetation, while P. sicula was numerically more abundant than P muralis in sunny and dry spots. Although conclusions based on the present data require further investigation, they seem to indicate that the studied urban l izard community is organized through specific ecological needs of each species rather than by species interactions.