Is there hybridisation between diploid and tetraploid Euphrasia in a secondary contact zone?

Our results suggest recent cross-ploidy hybridisation is rare or absent in a site of secondary contact in Euphrasia. While a strong ploidy barrier prevents hybridisation over ecological time-scales, such hybrids may form in stable populations over evolutionary time-scales and potentially allow for cross-ploidy introgression to take place. This article is protected by copyright. All rights reserved.