S'nailed+it

Contributing group members: Jay, Clayton, Hasan, Qassim, Luca, Chris.

Cepaea is a genus of moderate sized, air-breathing land snails which are cross-fertilizing hermaphrodites. The land snail Cepaea nemoralis tends to prefer warmer microclimates (Jones et al, 1977). It is considered an excellent candidate for polymorphism studies because of several phenotypic characteristics which include a range of shell colours such as brown, yellow and pink. They can also appear as either banded (3-5 stripes) or unbanded (0-1 stripes) (Harvey, 1976). These characteristics make their phenotypes easily identifiable. They are also abundant throughout Europe, are easy to find, and have limited mobility ( Pokryszko et al, 2012). These characteristics make it easy to differentiate between phenotypes that do well in sunny environments, as opposed to those which do well in shaded environments. It also allows for identifying phenotypes that do well in cold vs. warm environments. The habitats that are being looked at in this investigation include forested and grassy regions. Comparison of the phenotypes of this species of snail in different habitats will help to identify selective pressures and comparing snail populations within similar habitats will allow control for genetic drift and pseudoreplication. There may be some stochastic variables that we are not aware of, such as regions which have parasites, or regions with a high number of predators and in addition to this, other abiotic environmental factors that are beyond our control could influence the findings and results (Cameron & Cook, 2011).

In order to provide a means of assessing the success of the investigation a null hypothesis has been proposed: “There is no identifiable significant difference in phenotype between snails in different habitats.” The alternative hypothesis would therefore be as follows: “There is a significant, identifiable difference between the phenotypes of snails in different habitats”. Following data collection, a chi-squared test can be conducted to determine whether our findings are significant, to a 0.05 significance level. After analysis of the significance of the results and the trends or patterns observed, the null hypothesis can be accepted or rejected. An experimental design which takes into account the limited scope of the investigation and also the resources available, has been proposed herein. The two habitats that are going to be analyzed are the “trees zone” and the “grass zone”. The positions where Cepaea nemoralis populations will be sampled have been strategically placed taking into account the possibility of pseudoreplication and genetic drift effects. As explained later, it will be possible to assess and therefore avoid the effects of these during the analysis of the sampling results. Samples will be taken from two spots found in the same habitat and with a distance of 30m between them (e.g. T1 and T2). The aim of this is to be able to compare them and therefore ensure genetic drift does not interfere on relatively closely positioned morphs counts. </range id="468815858_8">The pair comprising the mentioned sampling spots will then be compared to another pair (T3 and T4), which is located relatively far from the previous pair. At the same time this pair is going to be positioned along the high-low altitude axis of the area. Comparing the results from two far positioned sample spots (or as in this case, pairs of spots) allows to check for pseudoreplication effects. Spots G1 and G2 are placed relatively close (approx. 30m) to the pairs of T spots which belong to a distinct environment such as the “grass zone”. Comparisons between the T spots and the closely located G spots allows assessment of the morph variation as a result of selective pressure in<range type="comment" id="468815858_9"> different habitat zones. </range id="468815858_9">It is also possible to compare the results from the whole high positioned spots triplet with the low positioned triplet in order to assess whether there is variation due to changing environment along the altitude axis. A more specific comparison can be made considering also some of the placed spots (e.g. only those in the grass zone – <range type="comment" id="468815858_10">G1 and G2)</range id="468815858_10">



The study <range type="comment" id="468815858_11">will allow for an indication as to the possible factors which may influence the presence of polymorphs</range id="468815858_11">. <range type="comment" id="468815858_12">Regrettably, due to time constraints and limited sample numbers, it will prove to be very difficult to ascertain definitive causes for the findings.</range id="468815858_12"> However, the study will contribute towards the ongoing debate amongst academics across the world, as to how polymorphism arises and is affected (Jones et al, 1977).