A genetic survey is to be carried out to try to prevent the adder species going extinct. British adders, also known as vipers, have been found with missing eyes and irregular spines. These signs of malformation point to inbreeding, which is a possible reason for decreasing numbers of adders in the wild.
Adders inhabit the edges of open ground and sheltered woodland areas but loss of meadows and heath land means their populations are diminishing. Around a third of the 1,000 individual populations in the UK are disappearing, with some groups having less than 10 adults in them.
Although it is illegal, there are still reports of adders being killed due to their venomous potential, even though the last known death from an adder bite was in 1975.
A lack of genetic diversity could be one of the reasons for the decrease in adder numbers, also explaining the appearance of abnormalities. A collaborative genetic survey by Oxford University, Natural England and the Zoological Society of London (ZSL) is being carried out at 16 locations across the UK to compare information from smaller populations against larger ones.
The aim is to see whether the smaller populations are actually suffering from a lack of genetic diversity. DNA samples are being taken from the adders’ vents, which is their excretory as well as genital orifice, as swabbing the mouth is potentially dangerous. Other possible reasons for diminishing adder numbers could be malnutrition or disease.
Maintaining genetic diversity is an issue for wildlife in the UK in general. This is due to increasing geographical isolation between populations. Solutions could come from allowing populations to mix, for example by changing farmland strips into meadow, thus creating wildlife “corridors”.
Adders are classed as “sentinel species” as they are high up the food chain. They eat small mammals such as mice, voles, shrews as well as lizards, which in turn eat grasses and insects. As such, a healthy adder population suggests a healthy ecosystem overall.
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