Schuivende hybridezones in kamsalamanders - Hybridezones blijken beweeglijker dan gedacht

Hybrid zone movement in crested newts Speciation typically involves a stage in which species can still exchange genetic material. Interspecific gene flow is facilitated by the hybrid zones that such species establish upon secondary contact. If one member of a hybridizing species pair displaces the other, their hybrid zone would move across the landscape. Such movement has occasionally been observed over years or even decades. This suggests that hybrid zones have the potential to traverse considerable distances over evolutionary time. Yet, the prevalence of such long-term hybrid zone movement is poorly understood. A key prediction of hybrid zone movement is that that the receding species leaves behind a trail of introgressed selectively neutral alleles within the expanding one. We test for such a genomic footprint of hybrid zone movement in two hybrid zones between crested newt species (genus Triturus) that are thought to have shifted position. The strongly asymmetrical and geographically extensive introgression we uncover in the two crested newt cases provide firm support for hybrid zone movement proceeding over considerable time and space.