No evidence for nuclear introgression despite complete mtDNA replacement in the Carpathian newt (Lissotriton montandoni)

Patterns of interspecific introgression may vary geographically, and the distribution of introgressed variants can yield insight into the historical dynamics of genetic interactions between hybridizing species. Urodele amphibians, often characterized by limited mobility, deep intraspecific genetic structuring and vulnerability to climatic changes, constitute suitable models for such historical inferences. Here, we combine an extensive survey of the mitochondrial (mtDNA) and nuclear (15 microsatellites) genomes in the Carpathian newt, Lissotriton montandoni (Lm) with species distribution modelling (SDM). Populations of the smooth newt, L. vulgaris (Lv) from the areas surrounding the Lm range were also sampled to test whether gene flow between these hybridizing species extends beyond the area of strict syntopy. The extent of introgression differs dramatically between the mitochondrial genome and the nuclear genome. While multiple, spatially and temporally distinct introgression events fro...