Cobras destras: evolução convergente da assimetria para a especialização funcional

Right-handed snakes: convergent evolution of asymmetry for functional specialization

Masaki Hoso1,*, Takahiro Asami2,3 and Michio Hori1
+ Author Affiliations

1Graduate School of Science, Kyoto University Kyoto 606-8502, Japan

2Department of Biology, Shinshu University Matsumoto 390-8621, Japan

3PRESTO, Japan Science and Technology Agency Kawaguchi 332-0012, Japan

Author for correspondence (hoso@terra.zool.kyoto-u.ac.jp)

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Abstract

External asymmetry found in diverse animals bears critical functions to fulfil ecological requirements. Some snail-eating arthropods exhibit directional asymmetry in their feeding apparatus for foraging efficiency because dextral (clockwise) species are overwhelmingly predominant in snails. Here, we show convergence of directional asymmetry in the dentition of snail-eating vertebrates. We found that snakes in the subfamily Pareatinae, except for non-snail-eating specialists, have more teeth on the right mandible than the left. In feeding experiments, a snail-eating specialist Pareas iwasakii completed extracting a dextral soft body faster with fewer mandible retractions than a sinistral body. The snakes failed in holding and dropped sinistral snails more often owing to behavioural asymmetry when striking. Our results demonstrate that symmetry break in dentition is a key innovation that has opened a unique ecological niche for snake predators.

Keywords:

handedness laterality parallel evolution molluscivore land snails

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