Scientists at Sheffield University have made a sheepish discovery it has been announced this week.
Dr Jacob Gratten and Dr Jon Slate, from the university’s Department of Animal and Plant Sciences, led an international team which has discovered why dark sheep on a remote Scottish island are mysteriously declining in a fashion seemingly contradictory to Darwin’s evolutionary theory.
The researchers found that the gene responsible for dark coat colour is linked to other genes which can reduce an animal’s fitness.
Dr Jacob Gratten said: “The aim of this study was to improve understanding of how evolution by natural selection operates. The study addresses an important problem in evolutionary biology.
“It shows that predicting the evolutionary response to selection is difficult without knowledge of which genes are in close proximity to each other. It also highlights that an understanding of the underlying genetic basis of a highly visible trait was necessary in order to understand its evolution.”
Coat colour of a feral population of Soay sheep on Hirta in the St Kilda Archipelago, where about three quarters of sheep have dark brown coats, was looked at for the study,
Darwin’s theory would have predicted that because dark-coated sheep appear fitter that they would do better than light-coated sheep until only dark-coated sheep remain in the area.
However, the study revealed that the process of evolution by national selection in Soay sheep is actually more complex than this.