In a study published yesterday, researchers from Manchester and Edinburgh universities have shown the power of selection (in this case natural selection by dog breeders) to rapidly change body shape. They looked at skulls from 47 St Bernard dogs dating back over 120 years – international breed standards for these dogs were established in the late 19th century. Since then skull shape has changed in a dramatic, and linear, fashion, to become closer to the ‘ideal’: their skulls are broader, the angle between the nose and the forehead has become steeper, and they’ve developed a more pronounced ridge above the eyes.
“We discovered that features stipulated in the breed standard of the St Bernard became more exaggerated over time as breeders selected dogs that had the desired physical attributes,” said Dr Klingenberg.“In effect they have applied selection to move the evolutionary process a considerable way forward, providing a unique opportunity to observe sustained evolutionary change under known selective pressures.”
Ref: Drake AG, Klingenberg CP. The pace of morphological change: historical transformation of skull shape in St Bernard dogs. Proc Royal Soc B 2007; DOI 10.1098/rspb.2007.1169 (subscription required)