Males and females of Hermann's tortoise (Testudo hermanni) exhibit a conspicuous yellow patch on both their cheeks, whose origin and potential function are totally unknown. In this study, we measured the extent and the colour intensity of these patches in 29 male and 19 female tortoises in order to test for sexual difference in these features. In addition, we analysed the relationships between patch features and body condition to investigate the possible function of these ornaments as status signals. We detected symmetric yellow patches in all sampled females, while five males did not show at all the ornament, and two had a yellow patch only on the left cheek. Although head and scale size, as well as RGB values, did not differ between sexes, female patches were significantly larger than those of males. In addition, the extent of cheek patches was correlated to female body condition, suggesting that these ornaments may have evolved as honest signals of quality through sexual selection processes driven by female-female contests over rank or by male mate choice.
The yellow cheek-patches of the Hermann’s tortoise (Reptilia, Chelonia): sexual dimorphism and relationship with body condition
GALEOTTI, PAOLO;SACCHI, ROBERTO;PELLITTERI ROSA, DANIELE;FASOLA, MAURO
2011-01-01
Abstract
Males and females of Hermann's tortoise (Testudo hermanni) exhibit a conspicuous yellow patch on both their cheeks, whose origin and potential function are totally unknown. In this study, we measured the extent and the colour intensity of these patches in 29 male and 19 female tortoises in order to test for sexual difference in these features. In addition, we analysed the relationships between patch features and body condition to investigate the possible function of these ornaments as status signals. We detected symmetric yellow patches in all sampled females, while five males did not show at all the ornament, and two had a yellow patch only on the left cheek. Although head and scale size, as well as RGB values, did not differ between sexes, female patches were significantly larger than those of males. In addition, the extent of cheek patches was correlated to female body condition, suggesting that these ornaments may have evolved as honest signals of quality through sexual selection processes driven by female-female contests over rank or by male mate choice.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
