Squirrels 'genetically altered' by forest

European red squirrels are common in Northern England

Red squirrels in Cumbria in Northern England have had their genetic make-up altered by the planting of a large conifer forest.

Kielder Forest in Northumberland provided a bridge between forest fragments, allowing an influx of new genes carried by "foreign" squirrels.

Scientists at Newcastle University have found the genetic composition of Cumbria's red squirrel population changed in the 1980s as a result.

The researchers, led by Marie Hale, said the findings had major implications for conservation management.

Genetic mixing

Red squirrels live in isolated patches of forest, which would normally prevent genetic mixing between populations.

Kielder Forest was planted in the 1920's

But the growth of the Kielder Forest, which was planted in the 1920s, started to form a link between squirrel populations by the 1960s.

The researchers suggested that man-made alterations on a landscape could result in genetic changes in animal and plant populations.

They studied genetic markers in 102 dried red-squirrel skins collected in northern England and southern Scotland.

According to their genetic "hallmarks", they were assigned to northern, eastern or western forest fragments.

'Stepping stone patches'

The study found that Cumbrian samples, or the western region, collected after the 1980s, were significantly different from earlier ones.

Kielder Forest prompted a north to west squirrel migration, which changed the Cumbrian population.

The findings are reported in the journal Science.

The researchers wrote: "The northern genes have leap-frogged through hundreds of forest fragments in a period of 20 years, demonstrating the use of stepping stone patches of forest by red squirrels."