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Université de Fribourg

Sympatric diploid and tetraploid cytotypes of Centaurea stoebe s.l. do not differ in arbuscular mycorrhizal communities and mycorrhizal growth response

Sudová, Radka ; Kohout, Petr ; Kolaříková, Zuzana ; Rydlová, Jana ; Voříšková, Jana ; Suda, Jan ; Španiel, Stanislav ; Müller-Schärer, Heinz ; Mráz, Patrik

In: American Journal of Botany, 2018, vol. 105, no. 12, p. 1995–2007

Genome duplication is associated with multiple changes at different levels, including interactions with pollinators and herbivores. Yet little is known whether polyploidy may also shape belowground interactions.Methods: To elucidate potential ploidy‐specific interactions with arbuscular mycorrhizal fungi (AMF), we compared mycorrhizal colonization and assembly of AMF communities in roots of...

Université de Fribourg

Biological invasion of oxeye daisy (Leucanthemum vulgare) in North America: Pre-adaptation, post-introduction evolution, or both?

Stutz, Sonja ; Mráz, Patrik ; Hinz, Hariet L. ; Müller-Schärer, Heinz ; Schaffner, Urs

In: PLOS ONE, 2018, vol. 13, no. 1, p. e0190705

Species may become invasive after introduction to a new range because phenotypic traits pre-adapt them to spread and become dominant. In addition, adaptation to novel selection pressures in the introduced range may further increase their potential to become invasive. The diploid Leucanthemum vulgare and the tetraploid L. ircutianum are native to Eurasia and have been introduced to North...

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

The population genetics of the fundamental cytotype-shift in invasive Centaurea stoebe s.l.: genetic diversity, genetic differentiation and small-scale genetic structure differ between cytotypes but not between ranges

Rosche, Christoph ; Durka, Walter ; Hensen, Isabell ; Mráz, Patrik ; Hartmann, Matthias ; Müller-Schärer, Heinz ; Lachmuth, Susanne

In: Biological Invasions, 2016, p. 1–16

Polyploids are overrepresented in invasive species. Yet, the role of genetic diversity and drift in colonization success of polyploids remains unclear. Here, we investigate genetic diversity, genetic differentiation and small-scale genetic structure in our model system, the three geo-cytotypes of Centaurea stoebe: monocarpic diploids and polycarpic (allo)tetraploids coexist in the native...

Université de Fribourg

Contrasting spatio-temporal climatic niche dynamics during the eastern and western invasions of spotted knapweed in North America

Broennimann, Olivier ; Mráz, Patrik ; Petitpierre, Blaise ; Guisan, Antoine ; Müller-Schärer, Heinz

In: Journal of Biogeography, 2013///n/a–n/a

Aim: The spotted knapweed (Centaurea stoebe), a plant native to south-east and central Europe, is highly invasive in North America. We investigated the spatio-temporal climatic niche dynamics of the spotted knapweed in North America along two putative eastern and western invasion routes. We then considered the patterns observed in the light of historical, ecological and evolutionary...

Université de Fribourg

Allopatric distribution, ecology and conservation status of the Pilosella alpicola group (Asteraceae)

Šingliarová, Barbora ; Šuvada, Róbert ; Mráz, Patrik

In: Nordic Journal of Botany, 2013, vol. 31, no. 1, p. 122–128

The Pilosella alpicola group comprises four morphologically distinct and geographically vicariant alpine taxa. We performed a thorough herbarium revision and literature survey to infer their distributional pattern(s). Pilosella alpicola s.s. occurs in the Alps in two disjunct areas: the Swiss Valais Alps and the Italian Dolomites. Historical records come also from the Austrian Alps (Gurktaler...

Université de Fribourg

Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones

Mráz, Patrik ; Španiel, Stanislav ; Keller, Andreas ; Bowmann, Gillianne ; Farkas, Alexandre ; Šingliarová, Barbora ; Rohr, Rudolf P. ; Broennimann, Olivier ; Müller-Schärer, Heinz

In: Annals of Botany, 2012, p. -

Background and Aims: In a mixed-ploidy population, strong frequency-dependent mating will lead to the elimination of the less common cytotype, unless prezygotic barriers enhance assortative mating. However, such barriers favouring cytotype coexistence have only rarely been explored. Here, an assessment is made of the mechanisms involved in formation of mixed-ploidy populations and coexistence of...

Université de Fribourg

Biosystematic study of the diploid-polyploid Pilosella alpicola group with variation in breeding system: Patterns and processes

Šingliarová, Barbora ; Hodálová, Iva ; Mráz, Patrik

In: Taxon, 2011, vol. 60, no. 2, p. 450-470

Members of the Pilosella alpicola species group (Asteraceae) are distributed throughout the alpine region of the European mountains (Alps, Carpathians, Balkan mountains). Like other Pilosella species groups (Hieracium subg. Pilosella ), the taxonomy and species' relationships are poorly understood mostly due to widespread facultative apomixis, frequent hybridization and polyploidization—the...

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...