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Université de Fribourg

Plant origin and ploidy influence gene expression and life cycle characteristics in an invasive weed

Broz, Amanda K ; Manter, Daniel K ; Bowman, Gillianne ; Müller-Schärer, Heinz ; Vivanco, Jorge M

In: BMC Plant Biology, 2009, vol. 9, p. 33

Background: Ecological, evolutionary and physiological studies have thus far provided an incomplete picture of why some plants become invasive; therefore we used genomic resources to complement and advance this field. In order to gain insight into the invasive mechanism of Centaurea stoebe we compared plants of three geo-cytotypes, native Eurasian diploids, native Eurasian tetraploids and...

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....

Université de Fribourg

Sawdust addition reduces the productivity of nitrogen-enriched mountain grasslands

Spiegelberger, Thomas ; Müller-Schärer, Heinz ; Matthies, Diethart ; Schaffner, Urs

In: Restoration Ecology, 2008///10.1111/j.1526-100X.2008.00424.x

Anthropogenic nutrient enrichment of mountain grasslands has boosted grasses and fast-growing unpalatable plants at the expense of slow-growing species, resulting in a significant loss in biodiversity. A potential tool to reduce nutrient availability and aboveground productivity without destroying the perennial vegetation is carbon (C) addition. However, little is known about its suitability...

Université de Fribourg

Potential contribution of natural enemies to patterns of local adaptation in plants

Crémieux, Lisèle ; Bischoff, Armin ; Šmilauerová, Majka ; Lawson, Clare S. ; Mortimer, Simon R. ; Doležal, Jiří ; Lanta, Vojtěch ; Edwards, Andrew R. ; Brook, Alex J. ; Tscheulin, Thomas ; Macel, Mirka ; Lepš, Jan ; Müller-Schärer, Heinz ; Steinger, Thomas

In: New Phytologist, 2008, vol. 180, no. 2, p. 524 - 533

Genetic differentiation among plant populations and adaptation to local environmental conditions are well documented. However, few studies have examined the potential contribution of plant antagonists, such as insect herbivores and pathogens, to the pattern of local adaptation.Here, a reciprocal transplant experiment was set up at three sites across Europe using two common plant species, Holcus...

Université de Fribourg

The importance of plant provenance and genotypic diversity of seed material used for ecological restoration

Bischoff, Armin ; Steinger, Thomas ; Müller-Schärer, Heinz

In: Restoration Ecology, 2009///doi:10.1111/j.1526-100X.2008.00454.x

The increased translocation of plant species for biodiversity restoration and habitat creation has provoked a debate on provenance and genotypic diversity of the used plant material. Nonlocal provenances are often not adapted to the local environmental conditions, and low population genotypic diversity may result in genetic bottlenecks hampering successful establishment. We tested provenance...

Université de Fribourg

Functional significance of triazine-herbicide resistance in defence of Senecio vulgaris against a rust fungus

Salzmann, Daniel ; Handley, Richard J. ; Müller-Schärer, Heinz

In: Basic and Applied Ecology, 2008, vol. 9, no. 5, p. 577-587

We investigated the functional significance of plant performance (dry mass, photosynthesis) in plant defence (resistance and tolerance) against pathogen infection, and potential negative cross-resistance between herbicide resistance and plant defence against disease. We compared isonuclear triazine-herbicide-resistant (TR) and -susceptible (TS) biotypes of Senecio vulgaris, in the presence and...

Université de Fribourg

Evidence of climatic niche shift during biological invasion

Broennimann, Olivier ; Treier, Urs A. ; Müller-Schärer, Heinz ; Thuiller, W. ; Peterson, A. T. ; Guisan, Antoine

In: Ecology Letters, 2007, vol. 10, no. 8, p. 701-709

Niche-based models calibrated in the native range by relating species observations to climatic variables are commonly used to predict the potential spatial extent of species’ invasion. This climate matching approach relies on the assumption that invasive species conserve their climatic niche in the invaded ranges. We test this assumption by analysing the climatic niche spaces of Spotted...

Université de Fribourg

Modeling the impact of a biocontrol agent, Puccinia lagenophorae, on interactions between a crop, Daucus carota, and a weed, Senecio vulgaris

Frantzen, J. ; Müller-Schärer, Heinz

In: Biological Control, 2006, vol. 37, no. 3, p. 301-306

The impact of a biocontrol agent spreading from a point source on crop–weed interactions was modeled. The model encompassed: (i) severity of crop–weed competition as affected by a rust pathogen, (ii) velocity of spread of the rust pathogen, and (iii) density of infected plants introduced in the weed population as starting points (inoculum sources) for an epidemic. The model was parameterized...

Université de Fribourg

Seed provenance matters — Effects on germination of four plant species used for ecological restoration

Bischoff, Armin ; Vonlanthen, Beatrice ; Steinger, Thomas ; Müller-Schärer, Heinz

In: Basic and Applied Ecology, 2006, vol. 7, no. 4, p. 347-359

The use of local seed provenances is often recommended in restoration and habitat creation because they are thought to be better adapted to local habitat conditions. However, spatial scales and the degree of population differentiation are not well known and germination is often not included in comparisons between provenances. We analysed germination as a key trait of plant development in five...