The convoluted evolution of snail chirality

  title={The convoluted evolution of snail chirality},
  author={Menno Schilthuizen and Angus Davison},
The direction that a snail (Mollusca: Gastropoda) coils, whether dextral (right-handed) or sinistral (left-handed), originates in early development but is most easily observed in the shell form of the adult. Here, we review recent progress in understanding snail chirality from genetic, developmental and ecological perspectives. In the few species that have been characterized, chirality is determined by a single genetic locus with delayed inheritance, which means that the genotype is expressed… 

Chiral Speciation in Terrestrial Pulmonate Snails

The fossil record and the recent fauna suggest that successful reversals in coiling direction occurred with a frequency of once every three to four million years for the Clausiliidae, and Turkey is nevertheless exceptional by both a high percentage of sinistral species and a high number of speciation events resulting in mirror image species.

The ecology of shell shape difference in chirally dimorphic snails

It is confirmed that hatchlings also differ in shell shape and field studies to compare dextral and sinistral juveniles and adults for direction and rate of dispersal within the vegetation and micro-niche occupation failed to detect any difference in both ecological traits.

Shells and heart: Are human laterality and chirality of snails controlled by the same maternal genes?

It is proposed that an evolutionarily conserved genetic basis of chirality (the same that controls left–right asymmetry in snails) is a major synapomorphy of the Bilateria.

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

This study mapped the proportions of sinistrals in 56 demes in A. inversus on the Malaysian island of Kapas and found no overwhelming evidence for a role for drift in explaining the deviations from equal S:D proportions.

Fine Mapping of the Pond Snail Left-Right Asymmetry (Chirality) Locus Using RAD-Seq and Fibre-FISH

The power of new genomic approaches for identification of the chirality gene, “D” is demonstrated and combining genomic technologies, such as RAD-Seq and high resolution FISH, is a robust approach for mapping key loci in non-model systems.

Multiple reversals of chirality in the land snail genus Albinaria (Gastropoda, Clausiliidae)

The fragmented population structure in Albinaria facilitates genetic drift and contributes to fixation of the opposite chirality and overcoming of the mating disadvantage of left–right reversal.

Speciation and Gene Flow between Snails of Opposite Chirality

The results imply that speciation by chiral reversal is only meaningful in the context of a complex biogeographical process, and so must usually involve other factors.

Sinistral snail shells in the sea: developmental causes and consequences

The common and widespread – while geologically short-lived – fossil shells of C. adversarius show large amounts of variability in form and this variation may be related, at least in part, to a pleiotropic effect associated with the reversed coiling direction of this species.

Opposite shell-coiling morphs of the tropical land snail Amphidromus martensi show no spatial-scale effects

Testing morph-clustering of empty shells at two spatial scales in Amphidromus martensi populations in northern Borneo shows that consistent clustering or separation of morphs cannot be clearly detected at any spatial scale and that predation is not frequency-dependent.




  • E. Gittenberger
  • Biology
    Evolution; international journal of organic evolution
  • 1988
The fact that snails are either sinistral or dextral may underlie a mechanism resulting in sympatric speciation, and several possible components in work on Partula are described, including chirality clines and assortative mating.

Population structure and coil dimorphism in a tropical land snail

It is concluded that population structure alone cannot stabilise the coil dimorphism in Amphidromus, and 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 apparentDimorphism at all larger scales.

The Inheritance of Sinistrality in Limnaea peregra (Mollusca, Pulmonata)

A spiral mode of cleavage in the egg and a spiral twist in the soft parts of the adult seem to be essential qualities of gastropod mollusca, and an animal which is neither dextral nor sinistral is presumably impossible : the twist being obligatory there is no third alternative.

Speciation and Gene Flow between Snails of Opposite Chirality

The results imply that speciation by chiral reversal is only meaningful in the context of a complex biogeographical process, and so must usually involve other factors.

Sex and darts in slugs and snails (Mollusca: Gastropoda: Stylommatophora)

The results emphasize that to understand the use of darts, then data are required from a wide range of species, and the realization that several characters are correlated may stimulate further research, and could eventually lead to some testable models for dart and mating behaviour evolution.

Reproductive character displacement by inversion of coiling in clausiliid snails (Gastropoda, Pulmonata)

A new case of possible reproductive character displacement in the direction of coiling, in the clausiliid snail Isabellaria dextrorsa, which is dextral in contrast with its nearest relatives, including I. torifera and I. lophauchena.

Ease of fixation of a change in coiling: computer experiments on chirality in snails

This paper explores the ease of fixation of a change in coiling direction, caused by an invasion of snails carrying a mutant chirality allele into a normal, homogeneous population, by using Monte-Carlo simulation, and confirms the expectation that heterosis can be very effective.

Asymmetric Mandibles of Water‐Scavenger Larvae Improve Feeding Effectiveness on Right‐Handed Snails

It is usually difficult to obtain direct evidence indicating how any particular asymmetric structure has any ecological significance or how the morphological chirality is related to the interspecies interaction with other animals.

Supergenes in polymorphic land snails. II. Partula suturalis.

The colour and banding of the shell of Partula suturalis are controlled by a single locus (M) with a series of at least six alleles and it is suggested that the locus may be complex.

The Inheritance of Sinistrality in Limnoea peregra

In 1920, one of the authors commenced breeding experiments with sinistral examples of the normally dextral species Limnœa peregra , and both pairs produced extensive broods which have now been carried down to the third, and in some few cases the fourth, filial generation.