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. 2021 Mar 18:60:e9.
doi: 10.6620/ZS.2021.60-09. eCollection 2021.

A Different Perspective on Sex Dimorphism in the Adult Hermann's Tortoise: Geometric Morphometry

Sokol Duro  1 , Ozan Gündemir  2 , Bektaş Sönmez  3 , Tefik Jashari  4 , Tomasz Szara  5 , Gülsün Pazvant  2 , Arben Kambo  6
Affiliations

A Different Perspective on Sex Dimorphism in the Adult Hermann's Tortoise: Geometric Morphometry

Sokol Duro et al. Zool Stud. .

Abstract

Eastern Hermann's tortoise (Testudo hermanni boettgeri) is a subspecies of Hermann's tortoise (Testudo hermanni) found in Albania. Gender determination is one of the crucial elements in determining the population dynamics in all species. Female and male adult tortoises look different, but these differences can be difficult to distinguish in captivity or when their sex indicators are deformed or injured. Therefore, the aim of this study was to use indirect and non-invasive methods such as geometric morphometric analysis to determine the sex of adult tortoises. For the geometric morphometry, 17 female and 23 male Hermann's tortoises were collected and photographed from the hills and mountains around the Tirana district of Albania between August and October 2019. Sexes were discriminated based on geometric morphometry, and plastron shape was a better indicator than carapace shape. In addition, abdominal, femoral and anal scutes on the plastron and the ratio of femoral to pectoral suture lengths were important for the sex distinction. Females had a larger plastron than males; this may have been supported by fecundity selection, because a large plastron suggests more volume in which to store eggs. The femoral and anal scutes were larger in male tortoises, and serve as a stronger base during mating. This study was conducted for adults only, and future studies are needed to determine if these indicators also apply to hatchlings and juveniles.

Keywords: Abdominal scutes; Albania; Geometric morphometry; Sex discriminate; Testudo hermanni boettgeri.

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Figures

Fig. 1.
Fig. 1.
HS: Humeral suture, PS: Pectoral suture, FS: Femoral suture.
Fig. 2.
Fig. 2.
Dorsal view of landmarks used for the carapace. A, Landmark points used on the photo. B, The differences between females and males are indicated by landmarks (MorphoJ). The round marks represent the female, and extensions from those marks indicate the direction and changes in the male turtles.
Fig. 3.
Fig. 3.
95% confidence ellipses for carapace landmarks (used past, Version 2.17c). PC1-PC2 and PC1-PC3. Blue dots are male; red dots are female.
Fig. 4.
Fig. 4.
Dorsal view of landmarks used for the plastron. A, Landmark points used on the photo. B, The differences between females and males are indicated by landmarks (MorphoJ). The round marks represent the female, and extensions from those marks indicate the direction and changes in the male turtles.
Fig. 5.
Fig. 5.
95% confidence ellipses for plastron landmarks (used past, Version 2.17c). PC1-PC2 and PC1-PC3. Blue dots are male; red dots are female.
See this image and copyright information in PMC

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