Sexual Size Dimorphism in Eastern Slow-Worm (Anguis fragilis colchica, Reptilia: Anguidae)

Tibor Sos, Gábor Herczeg


The direction and magnitude of inter-sexual differences in body and head size in one eastern slow-worm (A. f. colchica) population were investigated. We compared morphological measures of 92 male and 127 female adult A. f. colchica from a single population. In line with our expectations, we found that females were generally larger, but males had larger relative head size. At similar growth rate a disproportionate increase of head size in males and respectively of body size in females are pointed. The sexual difference in relative head size increased with the size (a proxy for age) of the animals. Our results fits well to the general theory, especially when studies of the reproductive biology of the species — reporting vigorous male-male combats, the presence of copulatory bites, and showing that female fecundity is size dependent — is taken into account. However, considering this generalist species, another common hypothesis suspecting dietary divergence between sexes behind sexual differences in relative head size is not likely to represent a strong evolutionary pressure in this case.


Anguis fragilis colchica; growth; sexual size dimorphism

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Anderson R. A. and Vitt L. J. (1990), «Sexual selection versus alternative causes of sexual dimorphism in teiid lizards», Oecologia, 84, 145 – 157.

Baird T. A., Vitt L. J., Baird T. D., Cooper W. E., Jr., Caldwell J. P., and Pérez-Mellado V. (2003), «Social behaviour and sexual dimorphism in the Bonaire whiptail, Cnemidophorus murinus (Squamata: Teidae): the role of sexual selection», Can. J. Zool., 81, 1781 – 1790.

Birkhead T. R., Johnson S. D., and Nettleship D. N. (1985), «Etrapair matings and mate guarding in the common murre, Uria aalgae», Animal Behav., 33, 608 – 619.

Cabela A. (1997), «Anguis fragilis Linnaeus, 1759», in: J.-P. Gasc, A. Cabela, J. Crnobrnja-Isailovic, D. Dolmen, K. Grossenbacher, P. Haffner, J. Lescure, H. Martens, J. P. Martínez Rica, H. Maurin, M. E. Oliveira, T. S. Sofianidou, M. Veith, and A. Zuiderwijk (eds.), Atlas of Amphibians and Reptiles in Europe, Societas Europaea Herpetologica and Muséum National d’Histoire Naturelle, Paris, pp. 196 – 197.

Camilleri C. and Shine R. (1990), «Sexual dimorphism and dietary divergence: Differences in trophic morphology between male and female snakes», Copeia, 1990(3), 649 – 658.

Capula M., Luiselli L., and Anibaldi C. (1992), «Biennial reproduction and clutch parameters in an alpine population of the slow-worm, Anguis fragilis Linnaeus, 1758 (Squamata: Sauria: Anguidae)», Herpetozoa, 5(3/4), 95 – 98.

Capula M., Anibaldi C., Filippi E., and Luiselli L. (1998), «Sexual combats, matings, and reproductive phenology in an alpine population of the slow-worm, Anguis fragilis», Herpetol. Nat. Hist., 6(1), 33 – 39.

Censky E. J. (1997), «Female mate choice in the non-territorial lizard Ameiva plei (Teiidae)», Behaviour, 132, 529 – 557.

Cooper W. E., Jr., and Vitt L. J. (1989), «Sexual dimorphism of head and body size in an iguanid lizard: paradoxical results», Am. Naturalist, 133(5), 729 – 735.

Cooper W. E., Jr., and Vitt L. J. (1993), «Female mate choice of large broad-headed skinks», Animal Behav., 45, 683 – 693.

Dely O. Gy. (1972), «Adatok a kárpát-medencei törékenygyík (Anguis fragilis Linnaeus) rendszertanához és elterjedéséhez [Data regarding the taxonomy and distribution of slow worm (Anguis fragilis Linnaeus) in Carpathian Basin]», Vertebrata Hung., 13, 39 – 79 [in Hungarian].

Dely O. Gy. (1974), «Über die Unterarten die Blindschleiche, Anguis fragilis L»., Vertebrata Hung., 15, 11 – 37.

Dely O. Gy. (1981), «Anguis fragilis Linnaeus, 1758 — Blindschleiche», in: W. Böhme (eds.), Handbuch der Reptilien und Amphibien Europas. Vol. 1, Academische Verlag, Wiesbaden, pp. 241 – 258.

Fairbairn D. J. (1997), «Allometry for sexual size dimorphism: pattern and process in the coevolution of body size in males and females», Annu. Rev. Ecol. Syst., 28, 659 – 687.

Grillitsch H. and Cabela A. (1990), «Zum systematischen Status der Blindschleichen (Squamata: Anguidae) der Peloponnes und der südlichen Ionischen Inseln (Griechenland)», Herpetozoa, 2(3/4), 131 – 153.

Günther R. and Völkl W. (1996), «Blindschleiche — Anguis fragilis Linnaeus 1758», in: R. Günther (ed.), Die Amphibien und Reptilien Deutschlands, Gustav Fischer Verlag, Jena, pp. 617 – 631.

Gvoždík L. and Boukal M. (1998), «Sexual dimorphism and intersexual food niche overlap in the sand lizard, Lacerta agilis (Squamata: Lacertidae)», Folia Zool., 47(3), 189 – 195.

Gvoždík L. and Van Damme R. (2003), «Evolutionary maintenance of sexual dimorphism in head size in the lizard Zootoca vivipara: a test of two hypotheses», J. Zool. (Lond.), 259, 7 – 13.

Johnson K., Dalton R. and Burley N. (1993), «Preferences of female American goldfinches (Carduelis tristis) for natural and artificial male traits», Behav. Ecol., 4, 138 – 143.

Luiselli L. (1993), «High philopatry can produce strong sexual competition in male adders, Vipera berus», Amphibia– Reptilia, 14, 310 – 311.

Luiselli L., Capula M., and Anibaldi C. (1994), «Food habits of the slow worm, Anguis fragilis (L.), in two contrasting alpine environments», Bull. Soc. Herpetol. France, 71 – 72, 45 – 58.

Madsen T. and Shine R. (1994), «Costs of reproduction influence the evolution of sexual size dimorphism in snakes», Evolution, 48, 1389 – 1397.

Malkmus R. (1995), «Aggressives Verhalten der Blindschleiche, Anguis fragilis Linnaeus, 1758», Herpetozoa, 9, 89 – 91.

McCoy J. K., Baird T. A., and Fox S. F. (2003), «Sexual selection, social behavior, and the environmental potential for polygeny», in: S. F. Fox, J. K. McCoy, and T. A. Baird (eds.), Lizard Social Behavior, Johns Hopkins Univ. Press, Baltimore, pp. 149 – 171.

Molina-Borja M. (2003), «Sexual dimorphism of Gallotia atlantica atlantica and Gallotia atlantica mahoratae (Lacertidae) from the Eastern Canary Islands», J. Herpetol., 37, 769 – 772.

Mouton P. le F. N., Flemming A. F., and Kanga E. M. (1999), «Grouping behavior, tail-biting behavior and sexual dimorphism in the armadillo lizard (Cordylus cataphractus) from South Africa», J. Zool., 249, 1 – 10.

Patterson J. W. (1983), «Frequency of reproduction, clutch size and clutch energy in the lizard Anguis fragilis», Amphibia–Reptilia, 4, 195 – 203.

Perry G. (1996), «The evolution of sexual dimorphism in the lizard Anolis polylepis (Iguania): evidence from intraspecific variation in foraging behavior and diet», Can. J. Zool., 74, 1238 – 1245.

Powell G. L. and Russell A. P. (1985), «Growth and sexual size dimorphism in Alberta population of the eastern short- horned lizard, Phrynosoma douglassi brevirostre», Can. J. Zool., 63, 139 – 154.

Riddell A. (1996), «Monitoring slow-worms and common lizards, with special reference to refugia occupancy and individual identification», in: J. Foster and T. Gent (eds.), Reptile Survey Methods, English Nature, London, pp. 46 – 60.

Smith N. D. (1990), The Ecology of the Slow-Worm (Anguis fragilis L.) in Southern England. Unpublished M.Ph. Thesis, University of Southampton.

Shine R. (1978), «Sexual size dimorphism and male combat in snakes», Oecologia, 33, 269 – 277.

Shine R. (1990), «Proximate determinants of sexual differences in adult body size», Am. Naturalist, 135, 278 – 283.

Shine R., Reed R. N., Shetty S., and Cogger H. G. (2002), «Relationships between sexual dimorphism and niche partitioning within a clade of sea-snakes (Laticaudinae)», Oecologia, 133, 45 – 53.

Thompson G. G. and Withers P. C. (2005), «Size-free shape differences between male and female Western Australian dragon lizards (Agamidae)», Amphibia–Reptilia, 26, 55 – 63.

Thorpe R. S. (1989), «Pattern and function of sexual dimorphism: a biometric study of character variation in the grass snake (Natrix natrix, Colubridae) due to sex and its interaction with geography», Copeia, 1989(1), 53 – 63.

Tomović L., Radojicic J., Džukić G., and Kalezić M. L. (2002), «Sexual dimorphism of the sand viper (Vipera ammodytes L.) from the central part of Balkan Peninsula», Russ. J. Herpetol., 9(1), 69 – 76.

Verwaijen D., Van Damme R., and Herrel A. (2002), «Relationships between head size, bite force, prey handling efficiency and diet in two sympatric lacertid lizards», Func. Ecol., 16, 842 – 850.

Vial J. L. and Stewart J. R. (1989), «The manifestation and significance of sexual dimorphism in anguid lizards: a case study of Barisia monticola», Can. J. Zool., 67, 68 – 72.

Vitt L. J. (1983), «Reproduction and sexual dimorphism in the tropical teiid lizard Cnemidophorus ocellifer», Copeia, 1983(2), 359 – 366.

Vitt L. J. and Cooper W. E., Jr. (1985), «The evolution of sexual dimorphism in the skink Eumeces laticeps: an example of sexual selection», Can. J. Zool., 63, 995 – 1002.

Wermuth H. (1950), «Variationstatistische Untersuchung der Rassen- und Geschlechtmerkmale bei der Blindschleiche (Anguis fragilis Linné)», Deutsche Zool. Z., 1, 81 – 121.



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