Climate change has had the finger pointed at it for shrinking sheep.

Soay sheep live on the island of Hirta, in the St Kilda archipelago, roaming free without any human interference. For the past five decades, they have been studied closely. One of the most puzzling aspects of the study is the fact that the average sheep size has shrunk in the past 20 years. Usually natural selection would look for larger sheep as smaller sheep may not survive hard winters and therefore not be able to reproduce, so the fact that the sheeps’ size has actually reduced has puzzled scientists.

Researchers at Imperial College London looked at the Price equation to see if a variable environment could possible produce the difference in sheep size. The Price equation describes how natural selection changes a population from one generation to the next. By modifying the equation to take into account different factors, the research team discovered several key things.

The first is that female sheep in their first breeding season tend to produce babies which are smaller than they were when they were born – this is the first time that the time of breeding vs the size of the sheep has been looked at.

The second factor showed that the warming of the climate meant that smaller sheep, which may not have survived when the temperatures were colder, are now surviving the winter therefore the average size of the sheep is going down over time.

Popularity: 1% [?]