Bergman’s rule and the Italian Hermann’s Tortoises (Testudo hermanni): latitudinal variations of size and shape

We used geometric morphometric analysis to investigate latitudinal variation in size and shape of carapace and plastron of I I I Testudo hermanni hermanni (60 males and 51 females) collected in 6 different Italian regions. Basing on a sample of 14 landmarks for carapace and 18 landmarks for plastron, we showed that the size and shape of both sexes changed according to a North-South cline following the Bergmann's rule, tortoises of Northern Italy being 1.1-1.2 larger than that of Southern Italy. Shape variation was higher in carapace probably because sexual selection in this species acts stronger on plastron than on carapace shape.