Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

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1 Character Evolution group, Naturalis Biodiversity Center, Leiden, The Netherlands
2 Institute Biology Leiden, Leiden University, Leiden, The Netherlands
3 Independent field biologist, Den Hoorn, The Netherlands
4 Independent field biologist, Singapore, Republic of Singapore
5 Terrestrial Zoology, Naturalis Biodiversity Center, Leiden, The Netherlands
6 Institute for Biodiversity and Ecosystems Dynamics, Computational Geo-Ecology, University of Amsterdam, Amsterdam, The Netherlands
7 Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
DOI
10.7287/peerj.preprints.470v2
Published
Accepted
Subject Areas
Ecology, Evolutionary Studies, Genetics, Zoology
Keywords
left-right asymmetry, predation, sexual selection, vegetation structure, density, population genetics
Copyright
© 2015 Schilthuizen et al.
Licence
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
Cite this article
Schilthuizen M, Looijestijn S, Chua SC, Aguirre Gutiérrez J, Castillo Cajas RF. 2015. Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus. PeerJ PrePrints 3:e470v2

Abstract

One of the very few snail taxa that display genetic antisymmetry (that is, roughly equal mixes of genetically determined clockwise [D] and anticlockwise [S] coiled individuals within a single population) are the circa 35 species of the tropical tree snail subgenus Amphidromus. Previous work has shown that this may be due to a particular type of sexual selection, in which sperm transfer is improved in copulations between the two mirror-image morphs. However, it is not yet clear why so often significant deviations from 50:50 proportions are found. Modelling studies show that population structure will affect the degree by which the dimorphism is skewed towards the morph associated with the recessive allele. In this study, we mapped the proportions of sinistrals (PropS) in 56 demes in A. inversus on the Malaysian island of Kapas. We also mapped population density, predation rates, and several measures of vegetation structure. Our results show that PropS amounts on average to 0.65, but across the island it varies from 0.30 to 0.85. Density and overall predation are inversely correlated. A general linear model selection procedure results in the proportion of sinistrals to be positively correlated with density and predation on dextrals. We find no overwhelming evidence for a role for drift in explaining the deviations from equal S:D proportions, but we do argue that further study of crab-snail interactions may be warranted.

Author Comment

This is the version as submitted to PeerJ after revision, prompted by the comments of two reviewers. In particular, the statistical analysis and the interpretation of the results have changed compared with the earlier version.

Supplemental Information

Supplementary File (data and model details)

This file contains the study's raw data, as well as details on the the GLM models selected.

DOI: 10.7287/peerj.preprints.470v2/supp-1