........................................................................................................................................... 5 Introduction ...................................................................................................................................6 Cochlearia ......................................................................................................................................6 Cochlearia officinalis s. lat. ........................................................................................................... 8 Research questions. ......................................................................................................................9 Material and methods ................................................................................................................. 13 Plant Material ............................................................................................................................... 13 Flow cytometry ............................................................................................................................ 15 DNA isolation .............................................................................................................................. 16 Microsatellite analyses ................................................................................................................ 16 RAD-seq analyses ........................................................................................................................ 18 Creating maps ............................................................................................................................. 20 Microsatellite data analyses ........................................................................................................ 20 RAD-seq data analyses ................................................................................................................ 24 Results ............................................................................................................................................ 25 Flow cytometry ........................................................................................................................... 25 Microsatellite analyses ................................................................................................................ 27 RAD-seq analyses ........................................................................................................................ 35 Discussion ..................................................................................................................................... 42 The closely related species in section Cochlearia ...................................................................... 42 The genetic aspect of the subspecies of C. officinalis ................................................................ 43 The polyploid origin of C. officinalis in Northern Scandinavia ................................................46 Further research .......................................................................................................................... 50 Conclusion ................................................................................................................................... 51 References ..................................................................................................................................... 52 Appendix.......................................................................................................................................... I