After completing a Bsc(Hons) in Zoology here at The University of Sheffield
I am now continuing my studies with a four year BBSRC PhD studentship. 
The following page provides a brief introduction to my PhD project. For more in-depth details of what exactly my project entails as well as a bit more 
information about me and my background please feel free to follow this link 
to my postgraduate student website: 

http://www.shef.ac.uk/aps/apsrtp/aps-rtp-2009/fellows-sarah/index.html

Molecular evolution is an area of evolutionary and molecular biology which is currently generating a lot of  interest. Genes involved in different functions undergo evolutionary change at different rates. Recent research has shown that many genes involved in reproduction are evolving up to twice as fast as genes not involved in reproduction  (Civetta & Singh 1995). This phenomenon has been observed across a wide variety of taxonomic groups including; Protozoa, Insects, Birds and Mammals.

 Some of the best studied rapidly evolving reproductive genes are those which encode the accessory gland proteins  (Acps) produced by male fruit flies, known as Drosophila. Acps have been particularly well studied in a species fruit  fly called Drosophila melanogaster. Males are thought to produce as many as 70-106 different Acps, with functions in  several important reproductive processes.

 Acps are produced, along with other seminal fluid components, in male reproductive organs known as the accessory  glands (Figure 1). They are then transferred, along with sperm, to the female reproductive tract during copulation.

Figure 1. A photograph of the reproductive system of a male Drosophila pseudoobscura. 
The testes, which produce the sperm, and the accessory glands in which the Acps are produced 
along with a majority of other seminal fluid components are labeled. Acps are transferred in 
the seminal fluid, along with the sperm, to the female during copulation.

 Once the Acps have been transferred to the female they can alter her physiology and behaviour, in a number of ways to  increase the males’ reproductive success. For example, an Acp known as Acp70A has been found to increase ovulation  (egg-production) and oviposition (egg-laying) rates in females upon transfer. This particular Acp also induces rejection  behaviour towards subsequent males by the female. Being able to exert these kinds of effects on females can  dramatically increase the number of offspring a male can sire in his lifetime. It is thought that because they play such key  roles in determining the reproductive success of males, Acps are subject to strong selective pressures leading to the high  rates of evolution observed.

 It has been suggested that sexual selection (the component of natural selection associated with reproductive success) is  responsible for this rapid rate of evolutionary change. However, whilst evidence collected to date does appear to  suggest this could be the case, as yet there is no direct experimental evidence in support of this idea. This leaves the  selective mechanisms driving the rapid evolution unclear. Therefore, using our D.pseudoobscura selection lines to  determine whether, and the extent to which, sexual selection is responsible for the rapid evolution of Acps is the primary  focus of my PhD.

 Previous research investigating the evolutionary responses to such varying levels of sexual selection has shown that E  males;

 Because re-mating patterns in both male and female Drosophila are known to be related to Acp function and/or  quantity these findings provide priliminary evidence that Acps produced by males from the different selection lines may  have altered as a result of sexual selection.

 In order to test this we will compare expression levels and allele frequencies between the selection line treatments in  order to detect any changes that may have occurred. 

 Once we have determined whether sexual selection is responsible for driving rapid evolution in Acps, this knowledge  can then be applied to gaining a better understanding of: