Université de Fribourg

Ploidy level and genome size variation in the homosporous ferns Botrychium

Dauphin, Benjamin ; Grant, Jason ; Mráz, Patrik

In: Plant Systematics and Evolution, 2016, vol. 302, no. 5, p. 575–584

Recent cytological and molecular studies have investigated genome size variation and evolution in the homosporous ferns, but representatives of the Ophioglossaceae were largely overlooked, despite their evolutionary singularity. Flow cytometry analysis was performed on 41 individuals of eight species of the genera Botrychium (B.), Botrypus, and Sceptridium to estimate their ploidy level...

Université de Fribourg

Allopolyploid origin of highly invasive Centaurea stoebe s.l. (Asteraceae)

Mráz, Patrik ; Garcia-Jacas, Núria ; Gex-Fabry, Emilie ; Susanna, Alfonso ; Barres, Laia ; Müller-Schärer, Heinz

In: Molecular Phylogenetics and Evolution, 2012, vol. 62, no. 2, p. 612–623

Spotted knapweed (Centaurea stoebe) occurs from Western Asia to Western Europe both as diploid and tetraploid cytotypes, predominantly in single-cytotype populations with higher frequency of diploid populations. Interestingly, only tetraploids have been recorded so far from its introduced range in North America where they became highly invasive. We performed phylogenetic and network analyses of...

Université de Fribourg

Interspecific hybridization in the genus Hieracium s. str.: evidence for bidirectional gene flow and spontaneous allopolyploidization

Mráz, Patrik ; Chrtek, Jindřich ; Fehrer, Judith

In: Plant Systematics and Evolution, 2011, vol. 293, p. 237–245

Although reticulation has indisputably played an important role in the evolutionary history of the genus Hieracium s. str. (Asteraceae), convincingly documented cases of recent interspecific hybridization are very rare. Here we report combined evidence on recent hybridization between two diploid species, Hieracium alpinum and H. transsilvanicum. The hybrid origin of...

Université de Fribourg

Geographical parthenogenesis, genome size variation and pollen production in the arctic-alpine species Hieracium alpinum

Mráz, Patrik ; Chrtek, Jindřich ; Šingliarová, Barbora

In: Botanica Helvetica, 2009, vol. 119, no. 1, p. 41-51

Hieracium alpinum L. (Asteraceae) is an arctic-alpine species distributed throughout Europe with both diploid and triploid cytotypes. We determined the ploidy levels of plants from 23 populations from Austria, Bosnia and Herzegovina, Finland, Italy, Norway, Romania, Slovakia, Switzerland and Ukraine. Data showed a non-overlapping pattern of cytotype distribution: sexually reproducing diploids (2n...