Université de Fribourg

Explaining the variation in impacts of non-native plants on local-scale species richness: the role of phylogenetic relatedness

Vilà, Montserrat ; Rohr, Rudolf P. ; Espinar, José L. ; Hulme, Philip E. ; Pergl, Jan ; Roux, Johannes J. Le ; Schaffner, Urs ; Pyšek, Petr

In: Global Ecology and Biogeography, 2014, p. -

Aim: To assess how the magnitude of impacts of non-native plants on species richness of resident plants and animals varies in relation to the traits and phylogenetic position of the non-native as well as characteristics of the invaded site.Location: Global.Methods: Meta-analysis and phylogenetic regressions based on 216 studies were used to examine the effects of 96 non-native plant species on...

Université de Fribourg

Polyploidy in phenotypic space and invasion context: a morphometric study of Centraurea stoebe s.l.

Mráz, Patrik ; Bourchier, Robert S. ; Treier, Urs A. ; Schaffner, Urs ; Müller-Schärer, Heinz

In: International Journal of Plant Sciences, 2011, vol. 172, no. 3, p. 386-402

The taxonomy of the Centaurea stoebe complex is controversial. Diploid and tetraploid plants occur in its native European range, but to date only tetraploids have been recorded from its introduced range in North America. We examined morphological differentiation of C. stoebe using multivariate and univariate approaches to clarify the taxonomic status of the known cytotypes. We measured more...

Université de Fribourg

Evidence for a combination of pre-adapted traits and rapid adaptive change in the invasive plant Centaurea stoebe

Henery, Martin L. ; Bowman, Gillianne ; Mráz, Patrik ; Treier, Urs A. ; Gex-Fabry, Emilie ; Schaffner, Urs ; Müller-Schärer, Heinz

In: Joural of Ecology, 2010, vol. 98, no. 4, p. 800–813

1. Introduced plants have the potential to rapidly evolve traits of ecological importance that may add to their innate potential to become invasive. During invasions, selection may favour genotypes that are already pre-adapted to conditions in the new habitat and, over time, alter the characteristics of subsequent generations. 2. Spotted knapweed (Centaurea stoebe) occurs in two predominantly...

Université de Fribourg

Shift in cytotype frequency and niche space in the invasive plant Centaurea maculosa

Treier, Urs A. ; Broennimann, Olivier ; Normand, Signe ; Guisan, Antoine ; Schaffner, Urs ; Steinger, Thomas ; Müller-Schärer, Heinz

In: Ecology, 2009, vol. 90, no. 5, p. 1366-1377

Polyploidy is often assumed to increase the spread and thus the success of alien plant species, but few empirical studies exist. We tested this hypothesis with Centaurea maculosa Lam., a species native to Europe and introduced into North America approximately 120 years ago where it became highly invasive. We analyzed the ploidy level of more than 2000 plants from 93 native and 48 invasive C....