Snailbob


 * Group Members:**

Shannen Seldon* Poppy Green Shamoli Ahmed Balnur Zhaisanbayeva April Li

After re-examining our strategy we have decided to keep our original design. It includes varying environments, independence, repetition and controls for certain variables. The strategy is outlined below:
 * Sampling Strategy:**

We will be taking samples from two parallel horizontal transects, one running through the grassland habitat and one through the woodland habitat. Each transect will have three samples equal intervals apart; each sample in grassland will be aligned with a sample in the woodland region so that there are effectively three 'pairs' of comparisons. The samples will be taken 25m apart (if possible) in order to isolate the populations (as the average travelling distance of the individuals is approximately 20m in a generation) so that they are independent of one another.


 * Strengths:**


 * We plan to take our samples from an area of flat ground in order to eliminate the factor of altitude on the phenotype of the population.
 * By only comparing two rather dissimilar habitats (grassland and woodland) we will hopefully be able to analyse any differences in phenotype with regards to these environmental factors only.
 * In distancing the samples over the average travelling distance, we are able to create independent populations and hence minimise the effect gene flow may have on the phenotype.
 * Taking three samples along the two transects increases the accuracy of our results; we are able to spot an anomaly within three samples, as opposed to only being able to compare between two.
 * This repetition also enables us to see if there is a consistent difference across the two habitats.


 * Weaknesses:**

> > > **Null Hypothesis (drift, gene flow, no selection):** > > Under the null hypothesis we must assume that any variations found will not be the result of natural selection. If this is the case we would expect to see variation frequencies that are not consistent across the repeated samples. For instance the ratio of one type of snail to another between one sample of woodland and grassland, would be completely different to that of another sample. This would also support the idea that natural selection is not in play as no one phenotype appears to benefit a population in a given environment. We are not agreeing with the null hypothesis, and believe that the alternative hypothesis is more likely to be supported by our results. > > **Alternative Hypothesis (drift, gene flow, selection):** > > The alternative hypothesis suggests that phenotypic variations between snail populations may in fact be a result of natural selection, as well as drift. Under this hypothesis we expect to find evidence of consistent phenotypic frequencies between the repeated samples. This would suggest that certain phenotypes convey a higher fitness on individuals in a given environment. We will need to make sure that there are significant variations that are consistent, so that these differences are not simply a result of sampling error. We are supporting the alternative hypothesis. >
 * In choosing not to take samples from the shrub region, we have eliminated a possible explanation for any phenotypic variations. We will be unable to analyse and take their possible effect into account.
 * As we have also controlled for altitude, we cannot examine the effect this factor may have on the phenotypic variations in the population either.
 * Due to the time restrictions, we have a limited sample set at one time point only and therefore our results and analysis may not be completely representative of the entire sampling area. An increase in the number of samples taken and samples taken over a longer time frame will lead to an increase in the accuracy and reliability of our results; and hence enable us to generate more conclusive results.