The ‘spread’ of the grey squirrel.

The 'spread' of the grey squirrel.

DNA profiling has many uses, notably in criminal investigations.  It often allows the identification of a victim, or can 'tie' a suspect to the scene of a crime.  However, it does have other uses.  When applied to animal populations, it can give information as to the origins of the population, the extent of inbreeding / outbreeding etc.  Recently, Dr Lisa Signorile (Imperial College, London) has applied DNA technology to the grey squirrel populations of the U.K. and Italy.

It has generally been accepted that the grey squirrels spread across the country quickly after they were introduced here in late Victorian times.   The various populations were thought to have interbred and expanded quickly.  However, Dr Signorile's results indicate the many of the U.K. grey squirrel populations are still genetically distinct, that is, the level of interbreeding has been limited.   The results also indicate that humans have had a significant hand in the introduction of grey squirrels to different area.  For example, the population of grey squirrels in Aberdeen are most closely related to populations found in Hampshire - near the New Forest.

squirrelOne person associated with the spread of the grey squirrel was the 11th Duke of Bedford  (Herbrand Russell).   Whilst he was involved in various animal conservation projects, he released and 'gifted' many grey squirrels from Woburn.  The populations of grey squirrels in Regent's Park, London are thought to have come from there.  The concept of invasive species was not current in Victorian times.

It is quite possible that humans are still aiding and abetting the spread of the grey squirrel - sometimes inadvertently.  For example, one squirrel captured on the Isle of Skye (in 2010) had come from Glasgow (as revealed by its genetic profile); it had stowed away under a car bonnet and escaped on Skye.  It is important that we are aware of how 'easy' it is for these animals to travel with us - their introduction to areas where the red squirrel is still established could be disastrous.

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