Snail+Snatchers


 * Eric Boateng
 * Ollie Britton
 * Alex Laybourn*
 * Sophie Nash
 * Jamil Razzaque

__Sampling Strategy__



__Revised Strategy__

We shall be performing 2 interrupted transects, with samples taken in all of the 3 habitats (grass, woodland & scrub). Each habitat type will be sampled at the same elevation on the site, as above. The sampling areas will be at least 20 m apart. In addition to standardising our criteria for polymorphisms (colour/shell bands etc.) we shall also be standardising the effort put into each sample area, using the same number of people searching an area for a set amount of time.

__Strengths of This Design__

As there are marked differences between habitats (eg. shade, background colour) selection for polymorphisms in each habitat could vary greatly. Each habitat will be sampled at the same elevation, reducing the differences amongst samples of the same habitat type. The interrupted transect is easy to replicate should no samples be found in any 1 site. Our method & results are standardised, facilitating collaboration with another group. As samples will be isolated by at least 20 m distance, the likelihood of gene flow between samples is reduced. As we are standardising not just measuring criteria, but also effort we will reduce bias resulting from intense searching of 1 area & barely searching another.

__Weaknesses of This Design__

We will only be sampling each habitat twice - more replication of results would be desirable. The habitats will also be differing in elevation; a variable outside of our control that could account for differences. The total number of sample sites is small.