Introduction-+Manos*,+Alija,+Ahad,+Sharisse,+Ziba,+Chris,+Fatima

Polymorphism is defined on the basis of genotypes and is defined as different f orms of alleles occurring at the same location and the same period of time.
 * __ Introduction for the Snail Trip Report: __**

The evolutionary processes that play a role in polymorphism are selection, genetic drift (changes in allele frequency ), gene flow (movement of alleles from a population to another) and mutation. In this experiment, we studied the morph frequencies in populations of the extremely polymorphic brown-lipped snails //Cepaea nemoralis// and we established a correlation between altitude and frequency of phenotypes.

//Cepaea nemoralis// is a species of land snails mostly found in Europe and is mainly used for genetics and evolutionary studies where these findings could be applied to humans. These snails are considered good model organisms as they carry their genes on their shells and are highly polymorphic. Traits include shell colour (yellow, pink or brown) and shell banding pattern (unbanded, middle banded and many banded). These snails are easier to study than humans mainly due to their small size and spread and their less mobility, which indicates genetic patterns will be limited to a small area thus enabling us to collect them in one locality and then studying their populations could be much easier unlike humans where gene flow is rather high.

Therefore, the aim of this experiment, which was carried out in Pulpit hill near Monk’s Riseborough, is to examine the power of evolutionary processes such as genetic drift, selection and gene flow on the polymorphic distribution of alleles in //Cepaea nemoralis// and to see which of these processes has the strongest effect. Another aim of this experiment is to see if the different environments such as altitude have different phenotype frequencies. Our sampling design enabled us to compare the phenotype of snails in different locations and consider what evolutionary process causes the observed samples.

The experimental design was carried out by observing the shell colour and band pattern of //Cepeae nemoralis// snails from different locations.Our group collected a minimum of thirty samples of snails from two different altitudes, uphill and downhill. First, a hypothesis was created, and then snails were collected from 4 different sites in those 2 altitudes (8 sites in total). Then, different variants of snails (shell colour and banding pattern) were recorded and a table was formed for comparison. The differences can be due to genetic drift, selection or gene flow. Our null hypothesis is that there would be no found effect of altitude on the phenotypes of the snails found in either high or low altitude. <span style="font-family: 'Times New Roman',serif; font-size: 14pt;">Natural selection occurs when advantageous <range type="comment" id="402168">trait is passed over generations and become common within one population. <span class="textexposedhide2" style="font-family: 'Times New Roman',serif; font-size: 14pt;"> If the polymorphism of snail is caused by natural selection, then phenotype frequency will vary with different types of habitats. In our case, two different habitats are located on different high altitudes. <range type="comment" id="722616">If this is not the case, then it is caused by genetic drift or gene flow. <span style="font-family: 'Times New Roman',serif; font-size: 14pt;">Another fact that might affect genetic variation is gene flow. In many species, not just the snails, there might be gene exchange between populations. When there is no form of barrier between the populations, then a few individuals from one population may meet with the individual species of another population. For example, if we find any population of snails that has mainly pink coloured shells but there are still some that are of different colour,<range type="comment" id="809126"> then that means that gene flow has occurred. Genetic drift is also another possible <range type="comment" id="879713">cause of polymorphism. It allows the fixation of a certain allele within an area, so that we can have populations of the same species but with different characteristics. Genetic drift occurs by chance and <span class="messagebody" style="font-family: 'Times New Roman',serif; font-size: 14pt;"> affects the differences in allele frequency in different areas. For example, genetic drift could increase the frequency of a phenotype in one area, and of another frequency in another area. <span style="font-family: 'Times New Roman',serif; font-size: 14pt;"><range type="comment" id="492078">The findings from this experiment will be analysed using a statistical chi squared test where in which the results would indicate if there were to be a statistical significance [significant difference] between the studied areas and the phenotypes found [between different locations] within them. __<span style="font-family: 'Times New Roman',serif; font-size: 14pt;">References: __

<span class="messagebody" style="font-family: 'Times New Roman',serif; font-size: 14pt;">Jones, J. S., Leith, B. H. and Rawlings, P. (1978). Polymorphism in Cepaea: a problem with too many solutions? Ann Rev Ecol Syst, 8: 109–143.

<span style="font-family: 'Times New Roman',serif; font-size: 14pt;">By: <span style="font-family: 'Times New Roman',serif; font-size: 14pt;">Ahad Al-Seraihi *Emmanouil Apostolidis <span style="font-family: 'Times New Roman',serif; font-size: 14pt;">Aliya Abilmazhinova Fatima Islam <span style="font-family: 'Times New Roman',serif; font-size: 14pt;">Charisse Fallaria Zanjani Shadman <span style="font-family: 'Times New Roman',serif; font-size: 14pt;">Christopher Constantinou