Morphology of the snake spectacle reflects its evolutionary adaptation and development

BMC Veterinary Research

Research Article

Mads Frost Bertelsen¹  Jacob Thorup Gade¹  Mari-Ann Otkjaer Da Silva²  Steffen Heegaard³  Tobias Wang⁴  Christian Damsgaard⁴ 

[1] Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, DK-1870, Frederiksberg, Denmark;Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, DK-1870, Frederiksberg, Denmark;Eye Pathology Section, Department of Pathology, Rigshospitalet, University of Copenhagen, Frederik V’s Vej 11, DK-2100, Copenhagen, Denmark;Eye Pathology Section, Department of Pathology, Rigshospitalet, University of Copenhagen, Frederik V’s Vej 11, DK-2100, Copenhagen, Denmark;Department of Ophthalmology, Rigshospitalet, University of Copenhagen, Nordre Ringvej 57, DK-2600, Glostrup, Denmark;Zoophysiology, Department of Biosciences, Aarhus University, DK-8000, Aarhus C, Denmark;

关键词: Eye;    Snake;    Spectacle;    Thickness;   

DOI  :  10.1186/s12917-017-1193-2

 received in 2017-02-05, accepted in 2017-08-11,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundCovering the eye of all snakes is a transparent integumental structure known as the spectacle. In order to determine variations in spectacle thickness among species, the spectacles of 217 alcohol-preserved museum specimens of 44 species belonging to 14 different families underwent optical coherence tomography (OCT) to measure spectacular thickness. Multivariable analyses were made to determine whether family, activity period (diurnal/nocturnal) and habitat (arboreal/terrestrial/fossorial/aquatic) influenced spectacle thickness.ResultsThe thinnest spectacles in absolute terms were found in the Usambara bush viper (Viperidae) with a thickness of 74 ± 9 μm and the absolute thickest spectacle was found in the red-tailed pipe snake (Cylindrophiidae) which had a spectacle thickness of 244 ± 57 μm. Fossorial and aquatic snakes had significantly thicker spectacles than arboreal and terrestrial snakes. When spectacle thickness was correlated to eye size (horizontal spectacle diameter), Gray’s earth snake (Uropeltidae) had the lowest ratio (1:7) and the cottonmouth (Viperidae) had the highest ratio (1:65). Multivariable and phylogenetic analyses showed that spectacular thickness could be predicted by taxonomic family and habitat, but not activity period.ConclusionThis phylogenetically broad systematic study of the thickness of the snake spectacle showed that spectacular thickness varies greatly across snake species and may reflect evolutionary adaptation and development.

【 授权许可】

CC BY   
© The Author(s). 2017

【 图 表 】

Fig. 6