Adder in a tube
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Adder DNA test to help halt decline

Ecologists are running DNA tests on adders to check their genetic diversity amid fears the UK's only venomous snake is vanishing from the wild.

A recent study found that numbers of the reptile had declined since 2007.

Conservationists believe inbreeding in small, isolated populations could lead to a further decrease in numbers.

The BBC's Louise Hubball joined snake expert Nigel Hand from the Zoological Society of London at a nature reserve in Somerset as he took a DNA sample from an adder.

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