News Release

Water vole genome will help boost conservation of one of UK's most endangered mammals

Peer-Reviewed Publication

Wellcome Trust Sanger Institute

A new tool to help conserve one of the UK's most threatened mammals has been released today, with the publication of the first high-quality reference genome for the European water vole. The genome was generated by scientists at the Wellcome Sanger Institute, in collaboration with animal conservation charity the Wildwood Trust, as part of the Darwin Tree of Life Project.

The genome, published today (24 June 2021) through Wellcome Open Research, is openly available as a reference for researchers seeking to assess water vole population genetics, better understand how the species has evolved and to manage reintroduction efforts.

The European water vole (Arvicola amphibius) is a small semi-aquatic mammal that lives on the banks of freshwater habitats and in wetlands. The species is native to Europe, west Asia, Russia and Kazakhstan. While the water vole's conservation status is 'least concern' worldwide*, populations in the United Kingdom have declined to such an extent that the species is considered nationally endangered. Habitat loss and predation by the American mink, an invasive alien species, have reduced the UK population from 7.3 million in 1990 to an estimated 132,000 in 2018**.

Water voles gained full legal protection in the UK in 2008. There have been a number of conservation projects in the UK aimed at supporting water vole populations, including efforts at habitat restoration and to control the population of American mink. There are also efforts to reintroduce the water vole in a number of restored urban and wild habitats, as well as mitigate the impact of new development***.

European water voles returned to Britain from ice-free refuges in Iberia and Eastern Europe after the last ice age, with these two clades contributing to genetic diversity in UK populations. This diversity may be apparent in certain traits, such as the black fur of Scottish water voles, which is distinct from those in England that tend to have brown fur. But the full wealth of genetic diversity cannot be estimated by appearance alone. It is also unknown how much diversity has been lost as a result of the recent population crash.

Hazel Ryan, Senior Conservation Officer at the Wildwood Trust, said: "Water voles are amazing animals and we don't fully understand what ecosystems lose without them. They are industrious habitat managers, almost like miniature beavers in the way they fell stems, make burrows and alter the landscape. We suspect that some water vole populations have become inbred in recent decades owing to shrinking numbers and the fragmentation of populations through habitat loss. The reference genome offers us a way to better understand genetic diversity for reintroductions and consider mixing individuals to ensure populations have the best chance to thrive."

To sequence the European water vole reference genome, a blood sample was taken from a live male A. amphibius individual that was part of the captive breeding population of the Wildwood Trust in Kent, UK. DNA was extracted from this sample and sequenced by scientists at the Wellcome Sanger Institute on Pacific Biosciences SEQUEL I and Illumina HiSeq X instruments.

Professor Rob Ogden, Director of Conservation Science at the University of Edinburgh, said: "Understanding the genetic diversity and structure of water vole populations is an important aspect of their conservation in the UK, and is central to international guidelines on the movement of wildlife for conservation management. The release of the water vole genome provides a comprehensive set of genetic tools to support the future sustainability of the species in the UK."

The water vole genome is published as part of the Darwin Tree of Life Project, which will see partner organisations sequence and assemble the genomes of 70,000 animal, plant, fungal and protist species across Britain and Ireland.

Professor Mark Blaxter, Programme Lead for the Darwin Tree of Life project at the Wellcome Sanger Institute, said: "The European water vole is a prime example of a British species whose genetic diversity we're in danger of losing before we've had chance to fully record it. This high-quality Arvicola amphibius reference genome will allow us to do that, as well as support ongoing conservation efforts to preserve existing populations and reintroduce new ones in a way that ensures these populations are genetically robust."


Contact details:

Dr Matthew Midgley
Press Office
Wellcome Sanger Institute
Cambridge, CB10 1SA
Phone: 01223 494856

Notes to Editors:

* IUCN Red List of Threatened Species
** Population estimate by Natural England
*** For more information, visit the Wildwood Trust website


Angus I. Carpenter, Michelle Smith and Craig Corton. (2021). The genome sequence of the European water vole, Arvicola amphibius Linnaeus 1758. Wellcome Open Research. DOI:


The Darwin Tree of Life Project is funded by Wellcome.

Selected websites:

About Wildwood Trust

Wildwood Trust opened in 1999 as a centre of excellence for the conservation of British wildlife, and was established as a registered charity in 2002. Wildwood is Kent's best British wildlife park. Home to over 200 native animals, past and present and set in 40 acres of beautiful ancient woodland where visitors can see bears, wolves, bison, deer, owls, foxes, red squirrels, wild boar, lynx, wild horses, badgers and beavers plus many more.

As one of the leading British animal conservation charities in the UK, Wildwood Trust is dedicated to saving Britain's most threatened wildlife. Wildwood Trust has taken part in many ground-breaking conservation programmes to date, which include, saving the water vole, using wild horses to help restore Kent's most precious nature reserves, bringing the extinct European beaver back to Britain and returning the hazel dormouse & red squirrel to areas where they have been made extinct.

The Wellcome Sanger Institute

The Wellcome Sanger Institute is a world leading genomics research centre. We undertake large-scale research that forms the foundations of knowledge in biology and medicine. We are open and collaborative; our data, results, tools and technologies are shared across the globe to advance science. Our ambition is vast - we take on projects that are not possible anywhere else. We use the power of genome sequencing to understand and harness the information in DNA. Funded by Wellcome, we have the freedom and support to push the boundaries of genomics. Our findings are used to improve health and to understand life on Earth. Find out more at or follow us on Twitter, Facebook, LinkedIn and on our Blog.

About Wellcome

Wellcome supports science to solve the urgent health challenges facing everyone. We support discovery research into life, health and wellbeing, and we're taking on three worldwide health challenges: mental health, global heating and infectious diseases.

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