The British Swallowtail diverged from its European cousins ​​earlier than thought, research finds | Butterflies

An endangered butterfly Papilio machaon britannicuswhich is only found breeding in Britain on the Norfolk Broads, has been a separate subspecies for at least 200,000 years, according to research.

Smaller, darker in color and less common than the continental swallowtail, britannicus it was previously thought to have developed its own variant when it became confined to the moorlands of eastern England 8,000 years ago, after the Doggerland floods.

But new genetic research suggests britannicus is a wetland specialist and may have once been widespread in the wetlands of northern Europe, diverging from its continental cousins ​​between 200,000 and 1.7m years ago.

Complete genome sequencing of swallowtail populations across Europe, published in the journal Insect Conservation and Diversity, found some evidence of inbreeding britannicus but he concluded that its survivors did not suffer from harmful genetic mutations.

This research is likely to change the way swallowtail conservation works in Britain. Some butterfly experts have recently argued that the continental swallowtail, Papilio machaon gorganuswhich is very common because its larvae feed on a variety of plants including fennel and wild carrot, may be brought to Britain and spread widely, which may include “less successful” britannicus no more.

But Mark Collins, president of the Swallowtail and Birdwing Butterfly Trust and author of the paper, said genetic variation. britannicus made it worth the renewed conservation effort. Britannicus it is found nowhere else in Europe and is in danger of extinction because global warming is causing rising sea levels that threaten its wetland habitats.

“We’re looking at the population of blind people in the Norfolk Broads which is not just a British remnant but a remnant from the wider distribution of wetlands across Europe,” said Collins. “Britannicus it is part of our natural heritage, it is protected by law for good reason because it is rare, and we should not allow it to be destroyed.”

In the wild, caterpillars of britannicus it will only feed on the rare marsh plant, milk parsley, which is why the butterfly is so rare in Britain.

Both the plant and the butterfly are threatened by rising seas causing salinity in the Norfolk Broads, England’s largest wetland. With most of Britain’s breeding population living at or below sea level, and salt water quickly killing milk parsley, these species will need to be moved to new wetlands protected from sea level rise over time.

Meanwhile, global warming made the continental swallowtail reach Britain regularly. It is often seen in Kent and Sussex and tends to breed successfully in these regions in good summers.

Although some lepidopterists believe that it is inevitable that the continental subspecies will eventually merge britannicus and put it together out of existence, says Collins britannicus they can survive in wetlands if they are given help.

“It is very likely that a variety of wetland species will survive in the future as well as the common swallowtail, the gorganusthe plane is circling a wide rural area,” he said. “Mixing may occur at the edges but britannicus we can survive if we save our wetlands.

“We know now that we’re dealing with a different butterfly that needs to be saved. We need to quickly identify the best sites to make sure we can plant milk parsley there and introduce the butterfly and it will thrive, whether it’s Lakenheath in Suffolk, Shapwick in Somerset or sites in Yorkshire. That’s the project we’re looking at.”

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