| dc.description.abstract | Hybridization is an important evolutionary force. It may lead to the formation of new, adaptive genotypes, or even the formation of a new species. However, it also may lead to replacement, or merging of species. Hybridization has long been suspected between Veronica spicata and V. longifolia in the Oslo area in southeastern Norway. The putative hybrids are said to backcross with V. spicata, forming a hybrid swarm. Because V. spicata is endangered (EN) Norway, it is important to investigate if ongoing hybridization takes place or if suspected hybrids are a part of a V. spicata which is more morphologically variable than presumed. Three specimens were sampled from each of six putative hybrid localities, five V. spicata and five V. longifolia localities in southeastern Norway. The following methods were used: morphometric analysis based on 26 morphological traits, pollen stainability as indication of fertility, flow cytometry for estimation of ploidy level, and Next-Generation Sequencing of 10 putatively unlinked marker regions using the Ion Torrent PGM: the nuclear regions ITS, CYC2, AroB EIF3E, At103 and Agt1, and the chloroplast regions trnS-trnG-trnG, trnQ-rps16, rpoB-trnC and trnL-rpl32. No evidence of ongoing hybridization was found. If the findings in this study can be extrapolated to the rest of the Oslo area, it seems that a broader concept of V. spicata should be implemented. However V. spicata, the putative hybrids and V. longifolia were rather admixed in the phylogenetic trees, suggesting that hybridization may have taken place earlier in the evolutionary history of V. spicata and V. longifolia. The pattern observed may also be explained by incomplete lineage sorting. Ancient hybridization cannot be separated from incomplete lineage sorting based on the current sample size. The flow cytometry revealed a tetraploid cytotype (2n = 68) of V. longifolia in southeastern Norway, which differ from the diploid cytotype (2n = 34) found in northeastern Norway and the rest of the Nordic countries. This may indicate that the southeastern population may have migrated from Southeastern Europe where the tetraploid cytotype is more prevalent. | eng |