Geographic (in-)variability of gender-specific traits in Hermann's tortoise

Abstract

We processed 40 morphological characteristics of 676 adult Hermann's tortoises (Testudo hermanni) (310 males and 366 females) from four localities in the central parts of the Balkan Peninsula. Analyses of variance and covariance showed significant differences between males and females in 38 and 35 traits, respectively. On the other hand, analyses of geographic variability within each gender, i.e. analyses of variance and covariance of separate traits between localities showed "constant" dimensions and proportions of several body parts. Most of the invariable traits were the elements of the rear portion of the tortoises' shell and free body parts, in both genders. Among these are some of the most prominent sexually dimorphic traits in T. hermanni. Therefore, we speculate that "standard" sizes of certain superficial bodily attributes in this species are conditioned by their role in gender discrimination, as well as courting and mating endeavours.