Genetic drift in divided populations – a factor in motorway design?

The M5 has, like many other motorways, been getting an upgrade to the central reservation. Moving from a steel barrier capable of stopping about 6 tonnes of vehicle by deformation up to thick concrete capable of stopping a large coach, er, dead (without permanent deformation) is obviously great for keeping traffic moving, but I fear it won’t be good for the local wildlife.

Aside from the junctions, there is simply no way anything like a fox or hedgehog could cross the line of the motorway. A 2 feet thick 4 feet high concrete wall seals off what must have already been quite the gauntlet to run – 6+ lanes of traffic! Of course at night such trips were formerly possible, but now, there is simply no way for anything that cannot fly or scale a sheer concrete surface.

I suspect that we will start to detect genetic drift in these populations, as inter-breeding will be near impossible now. This will further put pressure on already stressed small populations.

The flip side is that once animals learn the way is barred, they may avoid the motorway, further reducing accidents and also reducing the toll on the UK’s wildlife from road casualties.

Study is probably required.

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