Population structure and coil dimorphism in a tropical land snail

Schilthuizen, M., Scott, B.J., Cabanban, A.S. and Craze, P.G. (2005) Population structure and coil dimorphism in a tropical land snail. Heredity, 95 (3). pp. 216-220. ISSN 0018-067X

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Abstract

Tree snails of the subgenus Amphidromus s. str. are unusual because of the chiral dimorphism that exists in many species, with clockwise ( dextrally) and counter-clockwise ( sinistrally) coiled individuals co-occurring in the same population. Given that mating in snails is normally impeded when the two partners have opposite coil, positive frequency-dependent selection should prevent such dimorphism from persisting. We test the hypothesis that a strong population structure with little movement between tree-based demes may result in the fixation of coiling morphs at a very small spatial scale, but apparent dimorphism at all larger scales. To do so, we describe the spatial structure in a Malaysian population of A. inversus ( Muller, 1774) with 36% dextrals. We marked almost 700 juvenile and adult snails in a piece of forest consisting of 92 separate trees, and recorded dispersal and the proportions of dextrals and sinistrals in all trees over a 7-day period. We observed frequent movement between trees ( 155 events), and found that no trees had snail populations with proportions of dextrals and sinistrals that were significantly different from random. Upon recapture 1 year later, almost two-thirds of the snails had moved away from their original tree. We conclude that population structure alone cannot stabilise the coil dimorphism in Amphidromus.

Item Type: Article
Keywords: gene flow; frequency-dependent selection; fixation; chirality; Camaenidae
Schools and Departments: School of Life Sciences > Biology and Environmental Science
Subjects: Q Science > QH Natural history > QH0301 Biology > QH0540 Ecology
Q Science > QH Natural history > QH0301 Biology
Q Science > QL Zoology
Depositing User: Paul Craze
Date Deposited: 06 Apr 2009
Last Modified: 12 Mar 2017 05:38
URI: http://sro.sussex.ac.uk/id/eprint/2156

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