Genetics news | Genetics news

The scientists have made use of a unique poultry population to provide a new answer to a question that has haunted researchers since the early 20th century: what are the genetic mechanisms that allow breeders to create new populations where every individual is more extreme than the most extreme individual in the population that they started breeding from?

Since 1957 Paul Siegel, at Virginia Tech in the US, has studied the biological effects of selection for extreme body weight in chickens.

Starting from a homogeneous poultry population, he has bred two lines of chickens, one for high body weight and one for low body weight.

In the high line, the heaviest animals were chosen to be the parents of the next generation, and in the low line the lightest individuals were chosen.

Today the high line chickens weigh eight times as much as the low line chickens at eight weeks of age (see picture).

- This is one of the greatest responses to selection ever recorded in vertebrates and is considerably greater than disrupting the function of any of the individual genes that are known to have the largest impact on growth, says Leif Andersson, who initiated the genetic studies of poultry lines in collaboration...