Post-copulatory sexual selection and the evolution of reproductive tracts

A major question in reproductive biology is how sperm locate the ovum through the often long and tortuous female reproductive tract. Closely linked to this is the question of why females of internally fertilising species make it so difficult for sperm to locate their ova. One answer seems to be that reproduction for females is risky. If fertilisation is ‘too easy’ females of promiscuous species might lose control over which male fertilises their ova. Second, by allowing ‘foreign’ cells (i.e. spermatozoa) into their body, females might allow other cell types - notably pathogens - access, and sexually transmitted diseases are costly. Third, females require only a few spermatozoa to fertilise their ova, and yet because of sperm competition, males are under strong selection to inseminate very large numbers of sperm, yet too many sperm increases the risk of polyspermy, which is invariably fatal to embryos. While there is evidence that females can discriminate between the sperm of different males (cryptic female choice) the mechanism(s) remain unknown. The aim of this PhD is to test the idea that the anatomical and physiological complexity of the oviduct is driven by post-copulatory sexual selection. The study will be conducted on birds and the PhD will provide training in experimental design and light microscopy. The PhD is part of an ERC-funded grant to TRB. More details are available on request from Tim Birkhead (T.R.Birkhead@sheffield.ac.uk)

For more information about how to apply, or the application process, please contact Mrs S Carter (s.a.carter@sheffield.ac.uk).
To apply now go to: http://www.sheffield.ac.uk/postgraduate/online