In Europe, the distribution ranges of many species were pushed back to the Mediterranean region during glacials, the cold phases of the Pleistocene Ice Age. While the climate in present day temperate Europe deteriorated, species managed to survive in Mediterranean refugia, where conditions remained agreeable. When the next interglacial arrived, and the climate ameliorated as is the case in the current Holocene, species could recolonize temperate Europe. It is increasingly realized that some regions north of the Mediterranean region also remained habitable for species favoring a temperate climate. Arguably, the Carpathians were the most important of these ‘northern glacial refugia’. The Carpathians did not merely allow species to weather glacial periods. Recent studies suggest that a mosaic of habitat types was present and some species may have persisted in multiple range fragments. This pattern has been well-documented for the Mediterranean region. The phrase ‘refugia-within-refugia’ was coined to describe a scenario in which species survive and diverge in multiple discrete glacial refugia.

In a paper published in the Biological Journal of the Linnean Society we test whether the refugia-within-refugia scenario applies to the Carpathians for both a crested and a smooth newt species. As predicted, geographical genetic variation originated during, rather than after, the Pleistocene. Confirmation of refugia-within-refugia in these two ecologically distinct newt species suggest that the refugia-within-refugia scenario probably applies for quite some additional Carpathian species as well. Our findings emphasize the key role that the Carpathians played in Pleistocene survival and radiation of temperate Eurasia’s biodiversity.

Reference: Wielstra, B., Zieliński, P., Babik, W. (2017) The Carpathians hosted extra-Mediterranean refugia-within-refugia during the Pleistocene Ice Age: genomic evidence from two newt genera. Biological Journal of the Linnean Society 122(3): 605–613.

I initiated this work as a Newton International Fellow. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 655487.