The possible origin of the slow worm Anguis fragilis (Linnaeus, 1758) in Ireland
The introduction of alien species is often considered a global threat to biodiversity. In recent decades, the rate of introduction of alien herpetofauna has increased enormously, due mainly to the expansion of global trade. Although the distribution of reptiles is highly dependent on climate, global warming can lead to drastic changes in distribution of these animals in suitable geographical areas. In recent decades, many reptile species have been introduced, either unintentionally or intentionally, to sites outside their native ranges, for instance as a result of pet trade or passive transportation by boat. Reptiles can withstand long periods of starvation and desiccation, and many use small cavities as refuge, which increases their chances of being passively transported and allows both short- and long-distance range expansion.
Slow worms, the genus Anguis, represents legless lizards (Squamata: Anguidae) distributed in the Western Palearctic region. Recent phylogeographic analyses carried out with both mitochondrial and nuclear loci revealed that the genus is represented by five species. Today, there are a lot of discussions about differentiation of species this genus and where there is a contact zone between them but there are not study about introduction these lizards.
Ireland belongs among other areas of a potential biogeographic and/or conservation importance. Traditionally, Ireland was believed to be absent of slow worms. However, a supposedly introduced population of A. fragilis of unknown origin occurs in the Burren (western Ireland). Since then a number of further sightings have not been reported this species in Ireland. The origin of slow worms in Ireland was not known but it was generally accepted, though without any evidence or credibility, that they were introduced from Britain during the 1970s. But in 2020, Parry (2020) was publication more recent observations of slow worm in Ireland. If considering more recent observations of slow worm from various places in Ireland, and together with a lack of evidence of human-mediated introductions, a refugial character of the Burren population cannot be ruled out.
Therefore, phylogenetic studies of A. fragilis in Ireland and the monitoring of this species are top priorities in our study. The origin of this populations of this species are top issues in our project. Specifically, with this study we aim 1) the Irish populations are introduced or native, 2) discuss possible colonization routes and the origin of this species in Ireland, and 3) deduce implications of these findings. We will generate sequences of the DNA of samples and analyze them together with published data from across this genus’ native range. Thus, the knowledge of the origins and their phylogenetic relationships will largely contribute to the design of possible managements and strategies for this population in Ireland.
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Results
Saint Patrick, what about legless lizards? Tracing the mitochondrial affiliation and possible origin of Anguis (Squamata: Anguidae) population in Ireland
Ireland is home to only one native lizards’ species, the viviparous lizard and one of the few areas of the world where there are no native snakes. However, since the end of the 19th century, there have been reports indicating the presence of legless lizards, Anguis fragilis Linnaeus, 1758 population whose origin is unknown. As this genus has been intensively studied genetically and taxonomically in the past decade, we have decided to investigate newly obtained mtDNA sequences (ND2 gene) to trace affiliation of the Anguis population in Ireland. We genetically examined 12 individuals from the Burren area (western Ireland) and compared them to available data. The Irish population was identified as belonging to A. fragilis, specifically to the most common haplotype of the Illyrian-Central European haplogroup. This genetic affiliation is shared by populations across a wide European region, including the western Balkans, Spain, France, western Hungary, Austria, Germany, Latvia, Poland, the Czech Republic, Russia, Sweden, Norway, and Great Britain. Our findings showed that the Irish population does not exhibit unique mitochondrial variability. This haplotype is present across the range of the species, including Great Britain, which is not in contrast with the earlier hypothesis that nearby populations from this area, along with human-mediated introductions, could be the source of Anguis populations in Ireland. This is thus potentially the first documented case of Anguis introduction out of the native range. However, further research, including broader sampling in Great Britain and genomics, is required to determine and trace its exact origin.
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