Cytotype distribution and phylogeography of Hieracium intybaceum ( A steraceae)

Using flow cytometry and amplified fragment length polymorphism ( AFLP ), we explored the cytogeography and phylogeography of Hieracium intybaceum , a silicicolous species distributed in the A lps and spatially isolated in the V osges M ountains and the S chwarzwald M ountains. We detected two ploidies, diploid and tetraploid, but no triploid or mixed‐ploidy populations. Whereas diploids are sexual and distributed all across the A lps, tetraploids are apomictic and seem to be confined to the western A lps and the V osges. We detected a low level of genetic variation. B ayesian clustering identified four clusters/genetic groups, which are partly congruent with the ploidal pattern. The first two groups consisting exclusively of diploids dominate the whole distribution range in the A lps and show east–west geographical separation with a diffuse borderline running from eastern S witzerland to the eastern part of N orth T yrol. The third genetic group lacks a defined geographical range and includes diploid and tetraploid plants. The last genetic group comprises tetraploid plants in the F rench A lps and the V osges. We suppose that diploids colonized the deglaciated areas from source populations most likely located mainly in the southern part of the recent distribution range and occasionally also in the western A lps. Gene flow and further differentiation likely took place. Apomictic tetraploids most likely originated in the western A lps or in the refugium at the south‐western foot of the A lps. Their rather limited geographical range (partly contrasting with the theory of geographical parthenogenesis) can be explained by their rather recent origin. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society , 2015, 179 , 487–498.