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Université de Fribourg

Climatic suitability ranking of biological control candidates: a biogeographic approach for ragweed management in Europe

Sun, Yan ; Brönnimann, Olivier ; Roderick, George K. ; Poltavsky, Alexander ; Lommen, Suzanne T. E. ; Müller-Schärer, Heinz

In: Ecosphere, 2017, vol. 8, no. 4, p. -

Biological control using natural antagonists has been a most successful management tool against alien invasive plants that threaten biodiversity. The selection of candidate agents remains a critical step in a biocontrol program before more elaborate and time- consuming experiments are conducted. Here, we propose a biogeographic approach to identify candidates and combinations of candidates to...

Université de Fribourg

Neighbour origin and ploidy level drive impact of an alien invasive plant species in a competitive environment

Sun, Yan ; Müller-Schärer, Heinz ; Schaffner, Urs

In: PLOS ONE, 2016, vol. 11, no. 5, p. e0155712

Our understanding of the potential mechanisms driving the spread and naturalization of alien plant species has increased over the past decades, but specific knowledge on the factors contributing to their increased impact in the introduced range is still urgently needed. The native European plant Centaurea stoebe occurs as two cytotypes with different life histories (monocarpic diploids,...

Université de Fribourg

Origin matters: diversity affects the performance of alien invasive species but not of native species

Sun, Yan ; Müller-Schärer, Heinz ; Maron, John L. ; Schaffner, Urs

In: The American Naturalist, 2015, vol. 185, no. 6, p. 725–736

At local scales, it has often been found that invasibility decreases with increasing resident plant diversity. However, whether resident community diversity similarly resists invasion by alien versus native species is seldom studied. We examined this issue by invading constructed native plant assemblages that varied in species and functional richness with invasive alien or native Asteraceae...

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

Effects of soil fungi, disturbance and propagule pressure on exotic plant recruitment and establishment at home and abroad

Maron, John L. ; Waller, Lauren P. ; Hahn, Min A. ; Diaconu, Alecu ; Pal, Robert W. ; Müller-Schärer, Heinz ; Klironomos, John N. ; Callaway, Ragan M.

In: Journal of Ecology, 2013, p. -

Biogeographic experiments that test how multiple interacting factors influence exotic plant abundance in their home and recipient communities are remarkably rare. We examined the effects of soil fungi, disturbance and propagule pressure on seed germination, seedling recruitment and adult plant establishment of the invasive Centaurea stoebe in its native European and non-native North American...

Université de Fribourg

Dissecting impact of plant invaders: do invaders behave differently in the new range?

Sun, Yan ; Collins, Alexandra R. ; Schaffner, Urs ; Müller-Schärer, Heinz

In: Ecology, 2013, p. -

Knowledge from basic plant ecology suggests that impact of one plant species on another is driven by either competition for the same limiting resources, or by unique plant traits. These processes might be context specific, explaining a differential impact of exotic plant invaders in the native vs. introduced range. With the help of a conceptual framework, we aimed at identifying the relationship...

Université de Fribourg

Cytotype differences modulate eco-geographical differentiation in the widespread plant Centaurea stoebe

Hahn, Min A. ; Müller-Schärer, Heinz

In: Ecology, 2013, vol. 94, no. 5, p. 1005–1014

The evolution of optimal life history strategies is central for the fitness of organisms in a given environment. Besides divergent selection, other factors may determine regional patterns of differentiation and contribute to life history evolution. In a common-garden environment over three years, we examined life history differentiation across different eco-geographical regions and effects of a...

Université de Fribourg

Prospects for biological control of Ambrosia artemisiifolia in Europe: learning from the past

Gerber, E. ; Schaffner, Urs ; Gassmann, A. ; Hinz, H. L. ; Seier, M. ; Müller-Schärer, Heinz

In: Weed Research, 2011, vol. 51, no. 6, p. 559–573

The recent invasion by Ambrosia artemisiifolia (common ragweed) has, like no other plant, raised the awareness of invasive plants in Europe. The main concerns regarding this plant are that it produces a large amount of highly allergenic pollen that causes high rates of sensitisation among humans, but also A. artemisiifolia is increasingly becoming a major weed in agriculture. Recently, chemical...

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

Polyploidy and invasion success: trait trade-offs in native and introduced cytotypes of two Asteraceae species

Thébault, Aurélie ; Gillet, François ; Müller-Schärer, Heinz ; Buttler, Alexandre

In: Plant Ecology, 2010, vol. 212, no. 2, p. 315-325

Invasion success is favoured by the introduction of pre-adapted genotypes. In addition, novel pressures in the introduced range may lead to phenotypic changes related to fitness or competitive ability of introduced plants. Polyploidy appears to be over-represented in invasive plants, but differences between cytotypes in growth strategies including trade-offs among plant traits have received...