Body size miniaturization in a lineage of colubrid snakes: Implications for cranial anatomy

• Published in: Journal of anatomy 2021-01, Vol.238 (1), p.131-145
• Main Authors: Rajabizadeh, Mahdi, Adriaens, Dominique, De Kegel, Barbara, Avci, Aziz, Ilgaz, Çetin, Herrel, Anthony
• Format: Article
• Language: English
• Subjects: Adaptation; Allometry; Animals; Body size; Body Size - physiology; Colubridae; Dolichophis; Eirenis; Feeding apparatus; Feeding Behavior - physiology; Jaw; Life Sciences; miniaturization; morphology; Musculoskeletal system; myology; Original Paper; Original Papers; osteology; Skull; Skull - anatomy & histology; Snakes - anatomy & histology; Structure-function relationships
• ISSN: 0021-8782; 1469-7580
• DOI: 10.1111/joa.13293

As body size strongly determines the biology of an organism at all levels, it can be expected that miniaturization comes with substantial structural and functional constraints. Dwarf snakes of the genus Eirenis are derived from big, surface‐dwelling ancestors, considered to be similar to those of the sister genus Dolichophis. To better understand the structural implications of miniaturization on the feeding apparatus in Eirenis, the morphology of the cranial musculoskeletal system of Dolichophis schmidti was compared with that of the miniature Eirenis punctatolineatus and E. persicus using high‐resolution µCT data. The gape index was compared between D. schmidti and 14 Eirenis species. Our results show a relatively increased neurocranium size and decreased maximal jaw muscle force in E. persicus, compared with the D. schmidti, and an intermediate situation in E. punctatolineatus. A significant negative allometry in gape index relative to body size is observed across the transition from the Dolichophis to Pediophis and Eirenis subgenera. However, the gape index relative to head size showed a significant negative allometry only across the transition from the Dolichophis to Pseudocyclophis subgenus. In Dolichophis–Eirenis dwarfing lineages, different structural patterns are observed through miniaturization, indicating that overcoming the challenge of miniaturization has achieved via different adaptations. Dwarf snakes of the genus Eirenis are derived from big, surface dwelling ancestors, considered to be similar to the genus Dolichophis. In Dolichophis–Eirenis dwarfing lineages, different structural implications of miniaturization on the feeding apparatus are observed, indicating that overcoming the challenge of miniaturization has achieved via different adaptations.