Geographic variation of sexual size dimorphism and genetics in the European pond turtle, Emys orbicularis and Emys trinacris, of Italy

Abstract

We studied the extent of sexual size dimorphism (SSD) in the European pond turtle throughout most of its Italian distribution range using eight morphological parameters of 580 Emys specimens, describing populations from Italy and large Mediterranean islands. Sexual size dimorphism was evident in the whole sample, but not in all the considered areas. SSD in studied Emys likely mirrors different growth trajectories and body size architectures between sexes at adult stage. Italian populations resulted separated into five groups with morphological differences: (i) East Po plain Italy north to Apennines; (ii) Tyrrhenian Italy; (iii) Corse; (iv) Sardinia; and (v) southern Italy and Sicily. These results agree with previously reported data on systematics of Mediterranean populations. Some Italian populations were also tested using restriction endonuclease analysis of 18+28S ribosomal DNA on 43 specimens of eight localities. The occurrence of a restriction fragment length polymorphism of rDNA was also noted. Morphometric and molecular data revealed that the two Calabrian populations were significantly differentiated with respect to the other sampled populations. According to previous mitocondrial DNA analyses, our results also support the view that the southern Italy populations of E. orbicularis are different from other Italian populations, even if our results do not perfectly fit with previous works.