Snails+n+dat


 * __Introduction__**

The grove snail, //Cepaea nemoralis//, is a terrestrial mollusc found throughout Europe. The snail can grow to around 25mm in diameter and individuals exhibit a variety of polymorphisms. The colour of the shell can vary anywhere from brown to pink to yellow and the number of bands the shell has can vary between 0, 1, 3 or 5 (Rosin et al. 2013). The distinct phenotype reflects the genotype of the individual and allows them to be easily identified in conjunction with their slow paced lifestyle, making //C. nemoralis// a good model organism for studying evolutionary genetics.

From the observed phenotype, genotypic differences in the population can be inferred which could then be used to try and determine how genetic drift, gene flow and selection act on //C. nemoralis//. To reduce the influences of gene flow, distinct locations, far enough apart to isolate populations, should be chosen to determine whether variation in genotype is solely due to drift or drift as well as selection.

If selection is acting upon all populations in similar environments, there should be a significant similarity in phenotypic ratios in //C. nemoralis// populations at discretely isolated locations. However if drift is acting alone on genotype within each population there should be no observed similarities between populations.  Whiteleaf nature reserve in Monks Riseborough, abundant in distinct populations of C. nemoralis, is a chalk downland with readily available calcium essential for shell development.

Rosin, Z.M., Kobak, J., Lesicki, A. & Tryjanowski, P. ‘Differential shell strength of //Cepaea nemoralis// colour morphs-implocations for their anti-predator defence’ //Naturwissenschaften//, Volume 100, Issue 9, September 2013, pages 843-851