A genomic footprint of a moving hybrid zone in marbled newts

Abstract

AbstractWe 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 ofT. pygmaeusgenetic material was in aT. marmoratuspopulation 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 evidence for aT. marmoratusgenomic footprint inT. pygmaeusfrom the Serra de Sintra, near Lisbon. In combination with a previously reported southern, relic occurrence ofT. marmoratusin between both areas, the data point to the superseding with hybridization ofT. marmoratusbyT. pygmaeus. We estimate that the species hybrid zone has moved over a distance of ca. 215 km.