We developed a panel of 44 nuclear genetic markers and applied this to two species of marbled newts in the north (Triturus marmoratus) and the south (T. pygmaeus) of the Iberian Peninsula, to document pattern and process of interspecific gene flow. The northernmost occurrence of T. pygmaeus genetic material was in a T. marmoratus population north of the Vouga river estuary. This suggested the past presence of a hybrid zone, possibly coinciding with a natural river outlet at ca. 1200 A.D. Since 1808, the species contact has moved back south to a by then completed, man-made Vouga channel. We also found a T. marmoratus genomic footprint in T. pygmaeus from the Serra de Sintra, near Lisbon. In combination with a previously reported southern, relic occurrence of T. marmoratus in between both areas, the data point to the superseding with hybridization of T. marmoratus by T. pygmaeus. We estimate that the species hybrid zone has moved over a distance of ca. 215 km.

Provided are the raw Ion Torrent reads and the reads processed through the bioinformatics pipeline described in:

Wielstra, B., Duijm, E., Lagler, P., Lammers, Y., Meilink, W.R.M., Ziermann, J.M., Arntzen, J.W. (2014). Parallel tagged amplicon sequencing of transcriptome-based genetic markers for Triturus newts with the Ion Torrent next-generation sequencing platform. Molecular Ecology Resources 14(5): 1080-1089. (https://onlinelibrary.wiley.com/doi/full/10.1111/1755-0998.12242)