Why do animals have sex and how is genetic variation maintained?

Why do species reproduce sexually? Although this may sound like a simple question, it has captivated evolutionary biologists for many a decade. Reproducing sexually is often much more convoluted and time consuming than asexual reproduction, and may even disrupt a species’ adaptation to the environment. Yet nonetheless, many species reproduce sexually – either from time to time, or obligatory so. In this talk, I will discuss the ecological and evolutionary costs and benefits of sex, and how we use experimental evolution to try and disentangle those costs and benefits.

Long term studies of individuals living in the wild help us to understand ecological and evolutionary processes in great detail, and isolated islands are particularly informative due to their simplified ecosystems. Soay sheep have lived unmanaged on the islands of St Kilda for millennia and we have been studying the population living in one part of Hirta since 1985. Despite the relatively small population, the population retains considerable genetic variation, most obviously horn size, coat and colour. I will describe our investigations into how this variation is maintained in the population.