Abstract
BackgroundIn vertebrates, the left-and-right pairs of homologous organs are generally present in equal numbers. A remarkable exception is snail-eating snakes in the family Pareidae: almost all the pareid snakes have much more teeth on the right mandible than on the left for functional specialization in feeding on the dextral majority of land snails. Because the only exceptional species with symmetric dentition has been regarded as a slug-eater, the extent of dietary specialization on slugs could shape the degree of the lateral asymmetry of mandibular dentition (dentition asymmetry) even among snail eaters.MethodsTo test this, I compared the morphology and behavior of two sympatric species of Taiwanese snail-eating snakes, Pareas atayal and P. formosensis.ResultsSpecimens collected in the same locality showed that the dentition asymmetry of P. formosensis was significantly smaller than that of P. atayal. Congruent to its weak asymmetry, P. formosensis showed a strong preference of slugs to snails in the feeding experiment.DiscussionThe dietary specialization of P. formosensis on slugs would contribute to niche partitioning from the sympatric congener P. atayal. This study suggests that the diverse variation in the dentition asymmetry of pareid snakes is the result of their dietary specialization and divergence.
Highlights
Vertebrates are generally characterized by the lateral symmetry of external morphology; diverse animals represent conspicuous morphological differentiations in their left-and-right pairs of organs (Palmer, 1996; Palmer, 2005)
There were neither significant correlations of Snout-ventral length (SVL) with the numbers of left or right teeth (Fig. 1A; r = 0.23, p = 0.17 and r = −0.14, p = 0.65 for the right; r = 0.20, p = 0.22 and r = −0.41, p = 0.17 for the left in P. atayal and P. formosensis, respectively), nor those with asymmetry index (Fig. 1B; τ = −0.07, p = 0.58 and τ = 0.07, p = 0.75 in P. atayal and P. formosensis, respectively) in both snake species
P. atayal had 13.6 ± 1.0 left and 20.1 ± 1.1 right teeth and P. formosensis had 15.8 ± 1.0 left and 19.1 ± 1.1 right teeth (Fig. 2A): right-tooth number was significantly greater than left-tooth number in both snake species (Welch 2-sample t -test, p < 0.01 and p < 0.01, respectively)
Summary
Vertebrates are generally characterized by the lateral symmetry of external morphology; diverse animals represent conspicuous morphological differentiations in their left-and-right pairs of organs (Palmer, 1996; Palmer, 2005). The head parts of flatfish and the tusk of the narwhal are striking examples Even in these cases, asymmetric components of the paired organs are present in equal numbers since the early stage of their development. A notable exception is the tooth number of snail-eating snakes in the family Pareidae (often misdesignated as Pareatidae; Savage, 2015) in SE Asia, showing substantial difference between the left and right mandibles (dentition asymmetry: DA) (Hoso, Asami & Hori, 2007). How to cite this article Hoso (2017), Asymmetry of mandibular dentition is associated with dietary specialization in snail-eating snakes. This study suggests that the diverse variation in the dentition asymmetry of pareid snakes is the result of their dietary specialization and divergence
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
