A.Ali+Discussion

Discussion We hypothesised that in grassland habitats, lighter coloured snails with fewer bands will be observed, and in shrub land habitats, darker snails with a greater number of bands will be present. Our null hypothesis being that there will be no significant difference found between the habitats. The chi square results obtained indicate a statistical difference of phenotypic traits present at the two habitats that were analysed. A pattern in favour of light and fewer bands was observed in the grass habitat against the dark snails observed in the shrub habitat. This pattern correlates with other research studies carried out on //Cepaea nemoralis // polymorphism such as Jones (//1977) //which have shown similar findings. Apart from one shrub site, where the number of dark coloured shells was 1 less than light, the second and third shrub sites showed a difference of 9 and 13. When combined, the number of dark snails (51) is almost double that of light (28) in the shrubs which supports our hypothesis. However, the difference (12) in the grass habitat was not as large. Although this pattern may be a result of higher predation in the open grassland.

In reflection of our study the research was constrained to time and sunlight which could be bettered if it was carried out in the summer, allowing more sunlight and time to be spent in the reserve. Our experiment was carried out on a cold and dry day, which was not ideal as //C. nemoralis // like to emerge in warm and wet, thus our findings consisted of mainly dead snails. Also our observations were based on one day, therefore to improve reliability it may be suggested to take observations over a number of days, possibly spread throughout the year. Furthermore, other groups researched //Cepaea // polymorphism on the same day and so our results may have been skewed, as we observed clusters of snail shells at sites, which maybe a result of groups misplacing samples. Data found in such an arrangement should be avoided in future experiments. The reserve is open to the public so habitats may have been disturbed due to human and pet locomotion.

Our findings concur with our hypothesis; however concrete conclusions can not be made owing to factors such as sampling error. In order to reduce sampling error, more sampling sites should have been analysed. If time permitted, we could have repeated the experiment numerous times in each site and then attained an average. This would increase the accuracy, as similar results would indicate that there is a correlation rather than the results being due to human error or possibly even genetic drift. Moreover, a small sampling size does not represent the total population. Unfortunately we observed a small number of snails, therefore it would be difficult to generalise the results to larger populations.

In conclusion, the consistent pattern we observed of expected phenotypic traits that correlated to differences in the environment, suggest selection as the most probable process acting on the population. Genetic drift would produce differences uncorrelated with the environment, hence that may be ruled out as the key factor in light of our results.


 * Group Members:** Aman Ali, Bilal Tailor, Muhammad S Hasan, Moon Cherng, Mohsinoor Yemani