Plastral shape isometry in Western Hermann's tortoise (Testudo hermanni hermanni)

Abstract

Elliptical Fourier Analysis is a good technique for characterizing the shape of complex biological and non-biological morphologies. The current investigation aimed to study plastral pigmentation contour (black areas of the ventral shell) changes, according to body size (plastral length), in Western Hermann's tortoise (Testudo hermanni hermanni), using Elliptical Fourier Analysis. For this goal, 52 domestic pure tortoises from authorized private breeders were selected, ventral pictures were individually taken and their contour automatically digitized and straight-line plastron length obtained. Straight-line plastron length ranged from 83.6 to 150.6 mm (for males) and from 78.9 to 171.8 mm (for females). A regression was performed for second and third harmonics as dependent variables, against plastral length (log transformed) as independent variable. Based on this sample, it is demonstrated that plastral pigmentation design does not change along animals' life-history. Therefore, a plastral pigmentation shape isometry can be supposed, at least for this subspecies.