Aisha's+Group

Polymorphism is the raw material for evolution and differentiation. This experiment is carried out to understand why there is polymorphism in snails and why these geographic patterns can be seen you haven't explained the geographic patterns yet . The presence of multiple alleles in one population means that there is polymorphism. Cepaea nemoralis italics  (snails) are a prime example of this. something about the mapping of genotype onto phenotype The aim is to tell apart the relative contribution of genetic drift, selection or gene flow by looking at patterns of the snails in the field. It is a wide area with three valleys, some areas are bushy and some are open, where there will a varied sample of died and alive snails. The snails have lots of variants, which are based on imprecise  the banding and background colour of the shell of the snails. The genetics of these variants has been worked out and it wording ... what exactly is due to a single gene is due to a single soup you need to read up. Its not a soup-gene!!  gene, single locus, where there are alternative alleles which gives one allele to each of the variants This is one of the reasons for looking at snails. It is simple to use snails because to work out the genotype of the snail for these loci you only have to pick it up and look at it, and large sample sizes can be obtained. In addition to this, the patterns are on a local scale, because snails do not move about as much so have nice localized patterns which correspond in some cases to the environment lets not get ahead of ourselves... some studies have suggested that.. , so the process can be understood without great expenditure and on a small scale. That is why the best ideas came from investigations on snails and not on humans and all these discoveries are then applied to human genetics. good but you need references There is difference in the number of bands in the snails and the background colour varies from light to dark, but more specifically brown, pink and yellow. Some previous studies have found that The darker ones with lots of stripes are found in bushy woody areas and yellow ones with few stripes are found in open areas however, other studies (do your homework) . There are two hypothesises about the connection between background and banding, one is camouflage as there is lots of degradation look up the word  by the thrush as they have a particular stone they prefer for what?  so you can look at frequency of snails that have degraded nope <span style="font-family: Arial,sans-serif;"> and see which one stands out more in a particular habitat by being disproportionate again, look up the word <span style="font-family: Arial,sans-serif;">. Another is thermal biology as in shaded areas the snails are darker so that when in sunlight they warm up quicker you need to get the logic right, the suggestion ist that those snails which are darker, have a higher fitness, meaning.... hence they pass on their genes .... hence the frequency of dark morphs ... <span style="font-family: Arial,sans-serif;">. <span style="font-family: Arial,sans-serif; margin-bottom: 0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm;">Mutations introduce new variations within a population, drift and selection can change the frequency of the alleles within a population and gene flow can introduce new/ inappropriate/ beneficial variants into a population and it can also spread the variance which can increase frequency perhaps due to genetic drift to other surrounding populations. When explaining geographic patterns, you explain the relative contribution of all the different processes. much better <span style="font-family: Arial,sans-serif; margin-bottom: 0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm;">There is wide distribution in snails unclear, what do you mean <span style="font-family: Arial,sans-serif;">, so there is polymorphism logic seems wrong, how does a wide distribution cause polymorphism? <span style="font-family: Arial,sans-serif;"> but frequency of different variants changes from one locality to another. Are all patterns due to genetic drift and nothing to do with selection or vice versa? <span style="font-family: Arial,sans-serif; margin-bottom: 0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm;">In the experimental design, the affects of the different process will be distinguished. Is the differentiation between one population and another due to the fact that perhaps a mutation arose by genetic drift no, it would arise but mutation or be introduced by gene flow, but increase in frequency due to selection, drift or persistent gene flow from a population with high frequency, <span style="font-family: Arial,sans-serif;">and this is the region where it is spreading out very slowly by gene flow? Or is the difference between one population and another population due solely to genetic drift? Can we see evidence of the action of gene flow? <span style="font-family: Arial,sans-serif; margin-bottom: 0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm;">In the experiment we are only going to concentrate on one valley and replicate 3 times to increase accuracy not really the point, its to distinguish between the action of drift and selection <span style="font-family: Arial,sans-serif;">, during this experiment we are going to examine the difference in phenotype in snails between the shrubs and open land in one valley. This is so that we are able to understand if selection (environment) plays a part on the polymorphism of the snails. <span style="font-family: Arial,sans-serif; margin-bottom: 0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm;">In the same area, each sample will be taken from 500 paces apart from each other. This will allow a more even sampling ratio within that area. The sampling will be carried out in a 5mx5m area.

you have not explained how your different hypotheses would generate different patterns, and hence how you could distinguish between the action of the different processes that might be explaining the genetic patterns.

<span style="font-family: Arial,sans-serif; margin-bottom: 0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm;">group: tara, farha, asem, victoria, alaa and aisha (secretary)