Sexual selection maintains whole-body chiral dimorphism in snails

Schilthuizen, M., Craze, P.G., Cabanban, A.S., Davison, A., Stone, J., Gittenberger, E. and Scott, B.J. (2007) Sexual selection maintains whole-body chiral dimorphism in snails. Journal of Evolutionary Biology, 20 (5). pp. 1941-1949. ISSN 1010-061X

Download (512kB) | Preview


Although the vast majority of higher animals are fixed for one chiral morph or another, the cause for this directionality is known in only a few cases. In snails, for example, rare individuals of the opposite coil are unable to mate with individuals of normal coil, so directionality is maintained by frequencydependent selection. The snail subgenus Amphidromus presents an unexplained exception, because dextral (D) and sinistral (S) individuals occur sympatrically in roughly equal proportions (so-called ‘antisymmetry’) in most species. Here we show that in Amphidromus there is sexual selection for dimorphism, rather than selection for monomorphism. We found that matings between D and S individuals occur more frequently than expected by chance. Anatomical investigations showed that the chirality of the spermatophore and the female reproductive tract probably allow a greater fecundity in such interchiral matings. Computer simulation confirms that under these circumstances, sustained dimorphism is the expected outcome.

Item Type: Article
Keywords: Amphidromus, balanced polymorphism, chirality, Gastropoda, Malaysia.
Schools and Departments: School of Life Sciences > Biology and Environmental Science
Subjects: Q Science > QH Natural history > QH0301 Biology
Q Science > QL Zoology
Depositing User: Paul Craze
Date Deposited: 06 Apr 2009
Last Modified: 02 Jul 2019 20:21

View download statistics for this item

📧 Request an update