Team+Lena

INTRODUCTION

Tahsin Mojumader
Tanjila Uddin * Lena Rashid Lena Hansen Leena Halim

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In our experiment we set out to investigate the polymorphism and we used snail shells as our subject. There are a number of reasons why snails were preferred over other species i.e. humans. These are: firstly, polymorphism is fairly easy and simple to observe on snails as we are looking at differences in shell colour and number of bands. Not only is this easy but it is also simple and convenient as the polymorphism can still be observed after death. Secondly, snails are small and are found in large numbers. This is advantageous because it enables us to use a larger population which will provide us with more reliable results than a smaller population. It also gives us a more varied sample. Thirdly, investigating bands and shell colour of snails is a safe and environmentally friendly procedure. The shells are observed and placed back in their natural habitat so there is no disruption to their niche. =====

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The aim of our sampling is to find a pattern in polymorphism that correlates with the differences in environmental conditions. Polymorphism is when two or more clearly different phenotypes exist in the same population of a species. In this case we are looking at differences in shell colour (brown, pink, yellow) and number of bands (0-5). =====

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Our sampling method was a line transect which ran horizontally across the field in two different environments; three grassland and three shrub areas. Our sampling size was initially six different populations with 20 individuals per population and at 20metre intervals. <range type="comment" id="384400340_5">However on the day, we decided to increase our sampling size for more reliable results and therefore our new sampling size is 8 populations (20 individuals per population giving us 160 individuals in total) and 20 metre intervals was not possible as there were no 20 metre interval between grass and shrub and the area was mainly hills. Instead of 20 metre intervals we opted for 10 metre intervals. </range id="384400340_5">The reason we believe that a line transect would be the most appropriate method is <range type="comment" id="384400340_7">because it provides us with an even distribution of the area, it allows us to control confounding variables</range id="384400340_7"> such as altitude and a <range type="comment" id="384400340_8">10 metre interval ensures our </range id="384400340_8">samples were independent of one another and so results will not be due to gene flow. =====

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<span style="font-family: 'Calibri','sans-serif'; font-size: 14.6667px;">Our hypothesis is:There will be <range type="comment" id="384400340_9">a significant difference i</range id="384400340_9">n frequency of phenotypic polymorphs between the grassland and the shrub caused by genetic drift, gene flow and strong selection in the different environments. =====

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<span style="font-family: 'Calibri','sans-serif'; font-size: 14.6667px;"> The observations that would support our hypothesis are <range type="comment" id="384400340_10">consistency</range id="384400340_10"> within one area and differences between areas. For example, a specific colour of shells e.g. brown found abundantly in all shrub areas and a different colour found abundantly in the grassland areas e.g. pink. In the same manner, a certain number of bands would be found abundantly in either shrub or grassland but a difference between both. <range type="comment" id="384400340_11">The observations that would not support our hypothesis are similarities between two areas. For example pink shelled snails found abundantly in both shrub and grassland area. Also to have differences within one area. For example to find pink, brown and yellow snails in one shrub area.</range id="384400340_11"> =====