In biodiversity research, little is known so far about how hybridizations of a native and a non-native species can lead to the evolution of an invasive hybrid. A group of researchers led by Dr Madlen Stange is now studying this aspect in a project at Leibniz Insitute for the Analysis of Biodiversity Change - Zoological Research Museum Alexander Koenig (ZFMK). The group is investigating the spread of Phoxinus, an ecologically important schooling fish, in the River Sieg, a 155 km tributary of the River Rhine. The researchers are investigating the native and hybridized invasive populations on ecological, morphological, and genetic level to understand mechanisms and impact of hybridisation-invasions.