APRIL 1,
2019
by Shelley
Hughes, University
of York
New research
suggests a population of red squirrels on the Lancashire coast may have
developed weaker bites after snacking on peanuts.
The
researchers suggest that the changes in bite strength of the squirrels in
Formby could have been brought about by their softer diets, reducing their
ability to gnaw through the tough-to-crack nuts they eat naturally – such as
pine cone seeds, hazelnuts and beech nuts.
The findings
have important implications for conservation efforts for red squirrels, which were
once widespread across mainland Britain. They have suffered severe population
decline from the 1920s onwards due to a loss of woodland as well as viruses and
competition from grey squirrels.
Bite force
The
researchers, from the University of York and National Museums Scotland,
compared the lower jaws of red squirrels from surviving population pockets in
the UK (which are mainly in northern areas and on offshore islands) as well as
a sample from central Europe.
Their
analysis has indicated that Formby squirrels, which are managed by the National
Trust and the Lancashire Wildlife Trust, appear to have a less efficient
temporalis muscle than all the other red squirrel populations. In rodents this
muscle is used for rapid closing of the jaws to generate a powerful bite force.
Dr. Philip
Cox from the Department of Archaeology and the Hull York Medical School at the
University of York, said: "We found that the shape and function of the
lower jaws of the Formby squirrels were different from all of the other red
squirrel populations we looked at.
"They
are the only group of red squirrels in the study that were given supplementary
food and it is possible that the changes to their jaws have been brought about
by diet.
"Many
mammals- and especially rodents- have the capacity to evolve at very fast rates
under changing environmental conditions. The changes to the gnawing ability of
Formby squirrels could be an evolutionary response which has occurred over a
few generations of squirrels or it could be an adaptive response which occurs
over the lifetime of individual squirrels exposed to supplementary
feeding."
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