The research involved the study of both mitochondrial and nuclear, microsatellite, DNA. The authors showed that there is a division running through western Europe between the two forms. But there was more: evidence that the two forms were separate species rather than merely genetic lineages of the same species. A narrow hybrid zone was found between the two forms, indicating that while there is some mixing of genes, the selection against hybrids is strong and that there are intrinsic reproductive isolating mechanisms. In other words, there is evidence that the two forms are good biological species. An analogous case is that of the Yellow-bellied Toad of Western Europe (Bombina variegata) and the Fire-bellied Toad (B. bombina) of Eastern Europe.
I should point out that the hybrid zone between the two species of snake runs across Germany—where the research was done. That country, therefore, now has two grass snakes rather than one.
The split (or re-split since some earlier taxonomists regarded the species as separate) largely coincides with earlier morphological research done in the 1970s by Roger Thorpe, now of Bangor University in North Wales, who has written a useful comment on the new paper on ResearchGate including the rôle of the Ice Ages in causing the split.
At this stage, it was so far so good.
Anybody in Britain with the slightest knowledge of herpetology would have been surprised by the headlines that appeared in the media in early August. The Times, for example, carried the headline, ‘Snakes alive: new species has been living in England’. It and the rest of the British media, including not surprisingly the BBC, had clearly used a press release intended for the German media, since, while the name of ‘our’ grass snake changed to Natrix helvetica, we still had only the one species and not the two of the British media reports. I fired off a letter to The Times which was published on 12 August.
An article in a recent Herpetological Bulletin (British Herpetological Society) by two of the authors of the original paper gave a splendid explanation of what had happened:
This upheaval resulted from a complete misunderstanding of a press release by the Senckenberg Institution. The press release pointed out that Europe now has one more full snake species, which was misinterpreted as Britain gaining an additional snake species. In Brexit times, we have great sympathies with this approach. However, we have to face reality. Since the Kingdom of Hanover was lost from the United Kingdom in 1837, only one species of grass snake lives within UK borders (excluding a few introduced N. natrix and their offspring identified by our study). Until our paper was published (Kindler et al., 2017), the native British populations were assigned to the subspecies Natrix natrix helvetica, also widely distributed on the continent. Now, the strong evidence we presented indicates that this subspecies should be recognised as a full species, Natrix helvetica. Yet, this did not add another species to the British fauna, the British populations simply changed their identity label, as will all Britons when they leave the European Union. They will no longer be listed as EU citizens, but otherwise they will remain the same.Finally, a photograph of a British Natrix helvetica. This is from the 2nd (1954) edition of Malcolm Smith's book in the Collins New Naturalist series, The British Amphibians and Reptiles. The photographer was Walter S. Pitt:
Kindler C, Chèvre M, Ursenbacher S, Böhme W, Hille A, Jablonski D, Vamberger M, Fritz U. 2017. Hybridization patterns in two contact zones of grass snakes reveal a new Central European snake species. Scientific Reports 7: 7378. DOI:10.1038/s41598-017-07847-9
Fritz U, Kindler C. 2017. A very European tale – Britain still has only three snake species, but its grass snake is now assigned to another species (Natrix helvetica). Herpetological Bulletin 141, 44-45.
Peaker M. 2017. Snake in the grass. [Letter]. The Times, 10 August 2017.
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