Preliminary insights into genetic diversity and history of Nuphar lutea and N. pumila (Nymphaeaceae) in isolated southwestern European populations

•We investigate genetic variability of isolated populations of Nuphar lutea and N. pumila.•We sequenced nuclear ribosomal ITS and chloroplast intergenic spacers.•No evidence for southwestern European long-term refugium for Nuphar species.•Nuphar pumila and N. lutea spread from the Far East to Europe.•No signs of hybridization among Nuphar lutea and N. pumila were found. Recent phylogeographical study of Eurasian Nuphar species has revealed that after the subgenus diversificated in eastern Asia, N. pumila and N. lutea extended westwards to Siberia and further into Europe. However, isolated Nuphar populations from southwestern Europe were not included in previous phylogeographic study and their history remained unknown. Given the extreme rarity of N. pumila in southwestern Europe, the genetic study of degree and direction of introgression between this species and N. lutea in the region is highly warranted. We investigated the genetic variability of isolated populations of N. lutea and N. pumila from central France and northern Spain, using nuclear (ITS) and cpDNA sequences. We identified species-specific haplotypes and ribotypes for N. pumila and N. lutea. We found no evidence for southwestern European refugia for N. lutea and N. pumila and rather support the hypothesis of their migration from the East. We found no signs of hybridization between N. lutea and N. pumila. However, our results should be verified with more sensitive molecular markers.