Group+Eight+intro

Group members: Amber-Marie Loutfi, Serena Patel, Yolanda Lovelady, Manall Marakkar, Megan Stone, Rebecca McGarry, Jemima Rosen

Gene flow is the transfer of alleles or genes from one population to another. Gene flow has several important effects on evolution. Gene flow can occur within a population. When this occurs, genes can be introduced into the population, resulting in increased genetic variation. Additionally, gene flow can occur across populations. When this occurs, populations that are distinct and distant can become genetically similar to each other. In this scenario, the chance of speciation is reduced. This indicates that the less amount of gene flow present, the more likely that two populations will involve separately into two different species.

The main aim of the trip was to utilise our skills in conducting field work and working in teams to survey an area for evidence of gene flow, selection and genetic drift. We were specifically looking at these features in the populations of //Cepaea nemoralis// on the selection of shell colour polymorphism. These organisms have highly polymorphic shell patterns and are relatively straight forward to identify. We looked at populations with different all-over colours (brown, pink and yellow) and the number of bands (0,1,2,3...). We wanted to see how different locations varied in the types of snails found in them and pose theories as to why this occurred; i.e. due to genetic drift, gene flow, selection and so on - at the same time as avoiding pseudo-replication as much as possible.

We visited Monks Riseborough, which is a village in Buckinghamshire near the Chiltern Hills, to observe the species //Cepaea nemoralis// and the effects of gene flow on polymorphism of shells. We chose to focus on sites at a single altitude across areas of shrubs and larger plants compared to areas of short grass, to see whether a significant difference in the type of shell pattern most prominent existed. We would replicate both types of site to help verify whether any difference in pattern frequency between sites is due in some part to selection or simply genetic drift causing a single type of pattern to occur more often. To determine whether our results were significant, a statistical test will be used to calculate whether they are unlikely to be due to sample variation.

//C. nemoralis// is an ideal species to study for this experiment, as it has a short life span, living to around eight years, and inhabits a small area during its lifetime, which makes it <range type="comment" id="469136904_9">easier to observe, </range id="469136904_9">as well as<range type="comment" id="469136904_10"> to ascertain environmental effects upon it. </range id="469136904_10">//C. nemoralis// <range type="comment" id="469136904_11">has also been used </range id="469136904_11">as a model organism, a species used to observe processes so they may be better understood in other species, even humans. Studies of genetic diversity and its causes in //C. nemoralis// may <range type="comment" id="469136904_12">lead to better understanding of genetic diversity in humans and other eukaryotes.</range id="469136904_12">