Groupx+7


 * Kamran Sheikh
 * Miles Thorburn
 * Lucy McFarlane
 * Olivia Price
 * Joe Gibbons
 * Joe Thomas

=__** 1st Draft Map **__=


 * Abstract**

We aim to study //Cepaea nemoralis// and how distribution of polymorphisms may demonstrate the presence of a hybrid zone. Genetic drift occurs in all breeding populations, so the aim of this study is to demonstrate that the varation of phenotypes is directly the result of an established hybrid zone. //C. nemoralis// hybrids express varying shell phenotypes depending on the level of mixture between the different breeding communities.

We aim to gain experience in statistical analysis of the information gathered during this field course.

Disturbed habitats give rise to higher levels of distribution which would be a focal point of our sampling regime.

__Null Hypothesis__: There will be no observed phenotypic variation in populations collected from different habitats, implying no hybrid zone is present.

__Alternative Hypothesis__: There will be a significant phenotypic variation in populations collected from different habitats, implying a hybrid zone is present.


 * ‍Method and reasoning**‍

All sampling sites are 20m^2.

Site 1,3,4 - All of these sampling sites are entirely within one of the habitat types (woods, shrubs, and grass respectively) where we'd expect to see an established population of snails with little phenotypic variation.

Site 2,5 - Both of these sampling sites are at the edge of two different habitats (shrub and grass, wood and grass respectively). These areas would be disturbed habitats where we would expect to find populations with higher levels of phenotypic variation.

Site 6 - A control site higher altitude and away from the remaining sampling sites.

The aim of the study is to demonstrate the presence of a hybrid zone, to do this other factors such as height can be eliminated. Therefore, all sampling sites, except 6, are located at a similar height.

=__** 2nd Draft Map **__= = =


 * Method and reasoning**‍

All sampling sites are 20m^2.

Site 1,2,4,5 - All of these sampling sites are entirely within one of the habitat types (woods, shrubs, and grass respectively) where we'd expect to see an established population of snails with little phenotypic variation.

Site 3,6 - Both of these sampling sites are at the edge of two different habitats (shrub and grass, wood and grass respectively). These areas would be disturbed habitats where we would expect to find populations with higher levels of phenotypic variation.

The aim of the study is to demonstrate the presence of a hybrid zone, to do this other factors such as height can be eliminated. Therefore, all sampling sites are placed across different habitats along the same altitude.

=__** Final Draft **__=

The null hypothesis states there will be no observed polymorphic variation in populations collected from different habitats. In contrast, the alternative hypothesis infers there will be observed polymorphic variation in populations collected from different habitats.

= =
 * __Introduction - __**

Polymorphism is the occurrence of two or more differing phenotypes in the same population of a species. This phenomenon is caused by the presence of multiple alleles at the same locus in the genome, each with appreciable frequency.

//Ceapaea nemoralis // is a species of terrestrial snail found most commonly in Western Europe. The shell of //C.nemoralis// has a high incidence of polymorphism in their banding and colouring. This polymorphism has been studied extensively and various theories about its origins have been suggested including natural selection pressures, migration and random genetic drift. It is closely related to //Cepaea hortensis// which shares the same habitat and has a remarkably similar shell phenotype. The most reliable way to discern the two species is by the colouring of the aperture lip, which in //C.nemoralis// is nearly always dark brown and in //C.hortensis// is usually white.

The shell colour can vary wildly from being near white to yellow, pink or brown in addition to being banded or un-banded. There can be up to six bands present and they can vary in colour intensity and width. The relative simplicity of identifying the various polymorphisms of //C.nemoralis// have made it a common model organism for research by many, including John Silvertown of the Open University who stated "banded snails wear their genes on their backs", (Silvertown 2009 1 ). This ease of identification reduces the need for detailed studies of their genetics during studies, along with their very low dispersal rate per generation which serves to limit the effects of gene flow.

We aim to determine whether it is selective pressures driving the continued presence of //C. nemoralis// polymorphism or whether it is a blend of other mechanisms such as gene flow and genetic drift. Our final data was collected from Monks Risborough, Buckinghamshire in a rural area of varying altitude with sheltered woodland, open grassland and areas of built up shrubbery.</range id="530680580_4">

<span style="font-family: Arial,sans-serif; font-size: 9.5pt;"><range type="comment" id="530680580_5">We made our final decision on sampling locations when we got to the site, as we noticed a high number of snails present, along with a consistent altitude at the marked locations. This reduces our experimental variables whilst increasing the repetition of our sampling thus increasing the reliability of our experimental practice.</range id="530680580_5">


 * __<span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Definitions - __**

= = = = ==
 * <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Allele: **<span style="font-family: Arial,sans-serif; font-size: 9.5pt;"> One of the alternative versions of a gene at a given location (locus) along a chromosome
 * <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Locus: **<span style="font-family: Arial,sans-serif; font-size: 9.5pt;"> Physical site or location of a given gene on a chromosome
 * <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Genome: **<span style="font-family: Arial,sans-serif; font-size: 9.5pt;"> Entire set of genetic instructions found within a cell
 * <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Aperture (mollusc): **<span style="font-family: Arial,sans-serif; font-size: 9.5pt;"> Main opening of the shell, where the head-foot part of the organism's body emerges for locomotion, feeding etc.
 * <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Phenotype: **<span style="font-family: Arial,sans-serif; font-size: 9.5pt;">The observable physical and/or biochemical characteristics of the expression of a gene
 * <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Model organism: **<span style="font-family: Arial,sans-serif; font-size: 9.5pt;">A non-human species that is extensively studied to understand particular biological phenomena

Sites G1, G2, and G3 are located in the grass ~60 meters from sites W1, W2, and W3 which are all located in the woods. All woodland sites were a little further into than the map can represent. Glass collection sites were chosen on the basis of altitude that matched the woodland sites.

=__** Results **__=


 * || Woodland 1 ||  ||   ||   ||   ||   || Woodland 2 ||   ||   ||   ||   ||   || Woodland 3 ||   ||   ||   ||
 * || Live ||  || Dead ||   ||   ||   || Live ||   || Dead ||   ||   ||   || Live ||   || Dead ||   ||
 * Bands || Adults || Sub-Adults || Adults || Sub-Adults ||  || Bands || Adults || Sub-Adults || Adults || Sub-Adults ||   || Bands || Adults || Sub-Adults || Adults || Sub-Adults ||
 * Brown || - || - || - || - ||  || Brown || - || - || - || - ||   || Brown || - || - || - || - ||
 * 0 ||  ||   ||   ||   ||   || 0 ||   ||   ||   ||   ||   || 0 ||   ||   ||   || 2 ||
 * 1,2 ||  ||   ||   ||   ||   || 1,2 ||   ||   || 1 ||   ||   || 1,2 ||   ||   ||   || 1 ||
 * 3 ||  ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||
 * 4,5 ||  ||   ||   ||   ||   || 4,5 ||   ||   ||   ||   ||   || 4,5 ||   ||   ||   ||   ||
 * Pink || - || - || - || - ||  || Pink || - || - || - || - ||   || Pink || - || - || - || - ||
 * 0 ||  ||   || 2 ||   ||   || 0 ||   ||   || 1 || 2 ||   || 0 ||   ||   || 4 || 2 ||
 * 1,2 ||  ||   || 2 ||   ||   || 1,2 ||   ||   ||   || 1 ||   || 1,2 ||   ||   || 1 ||   ||
 * 3 ||  ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||
 * 4,5 ||  ||   || 4 || 5 ||   || 4,5 ||   ||   || 4 || 6 ||   || 4,5 ||   ||   || 3 || 2 ||
 * Yellow || - || - || - || - ||  || Yellow || - || - || - || - ||   || Yellow || - || - || - || - ||
 * 0 ||  ||   ||   ||   ||   || 0 ||   ||   ||   ||   ||   || 0 ||   ||   || 1 ||   ||
 * 1,2 ||  ||   || 2 ||   ||   || 1,2 ||   ||   || 2 ||   ||   || 1,2 ||   ||   ||   || 1 ||
 * 3 ||  ||   || 3 || 1 ||   || 3 ||   ||   ||   ||   ||   || 3 || 1 ||   || 1 || 1 ||
 * 4,5 ||  || 1 || 6 || 4 ||   || 4,5 || 1 || 2 || 7 || 3 ||   || 4,5 ||   || 1 || 3 || 5 ||
 * || Grass 1 ||  ||   ||   ||   ||   || Grass 2 ||   ||   ||   ||   ||   || Grass 3 || (near stream) ||   ||   ||
 * || Live ||  || Dead ||   ||   ||   || Live ||   || Dead ||   ||   ||   || Live ||   || Dead ||   ||
 * Bands || Adults || Sub-Adults || Adults || Sub-Adults ||  || Bands || Adults || Sub-Adults || Adults || Sub-Adults ||   || Bands || Adults || Sub-Adults || Adults || Sub-Adults ||
 * Brown || - || - || - || - ||  || Brown || - || - || - || - ||   || Brown || - || - || - || - ||
 * 0 ||  ||   ||   ||   ||   || 0 ||   ||   ||   ||   ||   || 0 ||   ||   ||   ||   ||
 * 1,2 ||  ||   ||   ||   ||   || 1,2 ||   ||   ||   ||   ||   || 1,2 ||   ||   ||   ||   ||
 * 3 ||  ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||
 * 4,5 ||  ||   ||   || 1 ||   || 4,5 ||   ||   ||   ||   ||   || 4,5 ||   ||   ||   ||   ||
 * Pink || - || - || - || - ||  || Pink || - || - || - || - ||   || Pink || - || - || - || - ||
 * 0 ||  ||   || 1 ||   ||   || 0 ||   ||   || 2 || 2 ||   || 0 ||   ||   ||   ||   ||
 * 1,2 ||  ||   ||   ||   ||   || 1,2 ||   ||   ||   ||   ||   || 1,2 ||   ||   ||   || 4 ||
 * 3 ||  ||   || 1 ||   ||   || 3 ||   ||   ||   ||   ||   || 3 ||   ||   ||   ||   ||
 * 4,5 ||  ||   || 1 || 1 ||   || 4,5 ||   ||   ||   ||   ||   || 4,5 ||   ||   ||   ||   ||
 * Yellow || - || - || - || - ||  || Yellow || - || - || - || - ||   || Yellow || - || - || - || - ||
 * 0 ||  ||   ||   || 2 ||   || 0 ||   ||   || 2 || 9 ||   || 0 ||   ||   || 4 || 4 ||
 * 1,2 || 1 ||  || 4 ||   ||   || 1,2 ||   ||   ||   ||   ||   || 1,2 ||   ||   ||   ||   ||
 * 3 ||  ||   ||   || 2 ||   || 3 ||   ||   || 2 || 3 ||   || 3 ||   ||   ||   || 4 ||
 * 4,5 ||  || 2 || 11 || 3 ||   || 4,5 || 2 || 2 || 3 || 3 ||   || 4,5 ||   ||   ||   ||   ||
 * To avoid a cluttered table blank cells represent a 0
 * To avoid a cluttered table blank cells represent a 0

__References__ <span style="color: #ff0000; font-family: Arial,sans-serif; font-size: 9.5pt;">1 <span style="font-family: Arial,sans-serif; font-size: 9.5pt;">Silvertown, J 2009, Evolution MegaLab, 9 May 2009, Science Buzz. Available from: < http://www.sciencebuzz.org/blog/evolution-megalab-launches-evolution-mega-study>. [12 November 2014]