Shrinking Sheep Shocker

Scottish sheep are shrinking! Each new generation of sheep on the Scottish island of Hirta are smaller than the last. Shorter, warmer winters, caused by climate change, are tampering with normal sheep evolution.

Professor Tim Coulson, of the Imperial College London's Life Sciences Department, sums up what exactly is happening to sheep evolution on this island:

In the past, only the big, healthy sheep and large lambs that had piled on weight in their first summer could survive the harsh winters on Hirta. But now, due to climate change, grass for food is available for more months of the year, and survival conditions are not so challenging - even the slower growing sheep have a chance of making it, and this means smaller individuals are becoming increasingly prevalent in the population.

In a study reported in the journal Science, the research team also blames something called the "young mum effect." Since ewes are giving birth at younger ages, they produce smaller offspring.

This effect explains why the sheep are not getting bigger over time, but the study suggests that climate change is the main culprit for the shrinking sheep. On the upside, smaller sheep also means cuter sheep pictures on the internet!

Climate change and the mystery of the shrinking sheep [via EurekaAlert]
The Dynamics of Phenotypic Change and the Shrinking Sheep of St. Kilda [via Science]