COMPETITION AND MORPHOLOGICAL SIMILARITY - THE CASE OF THE SNAKE-LIKELIZARDS ANGUIS-FRAGILIS (ANGUIDAE) AND CHALCIDES-CHALCIDES (SCINCIDAE)

Anguis fragilis and Chalcides chalcides are phylogenetically unrelated , morphologically similar, elongated ''snake-like'' shaped lizards, wh ich are frequently sympatric in Mediterranean Europe. The potential fo r competition between these two species was studied in several localit ies of northern and central Italy. Results show that: (I) A. fragilis was longer than C. chalcides in every studied population; (2) the taxo nomic composition of the diet, and very probably even the mean prey si ze, were very different between the two species; (3) neither the diet composition nor the food niche breadth of any of the two species did s ignificantly change when the potential competitor was available in the environment; (4) A. fragilis and C. chalcides were very different in terms of daily activity rhythms, and their activity patterns did not c hange significantly if the one species was alone or with the potential competitor; (5) the habitat requirements were different between the t wo species, A. fragilis being more linked to wooded areas than C. chal cides. However, the two species occurred together in several areas wit hin the studied territory. The potential for interspecific competition , thus, seems to be low.