plant invasions; herbivory; polyploidy; biological control; biogeographic comparison; Centaurea; evolution
(2013), Cytotype differences modulate eco-geographical differentiation in the widespread plant Centaurea stoebe, in Ecology
, 94(5), 1005-1014.
(2013), Cytotypes of Centaurea stoebe found to differ in root growth using growth pouches, in Weed Research
, 53(3), 159-163.
(2013), Dissecting impact of plant invaders: do invaders behave differently in the new range?, in Ecology
, 98(10), 2124-2130.
(2013), Effects of soil fungi, disturbance and propagule pressure on exotic plant recruitment and establishment at home and abroad, in Journal of Ecology
, 101(4), 924-932.
(2013), Increased seed survival and seedling emergence in a polyploid plant invader, in American journal of botany
, 100(8), 1555-1561.
(2012), Allopolyploid origin of highly invasive Centaurea stoebe sl (Asteraceae), in Molecular Phylogenetics and Evolution
, 62(2), 612-623.
(2012), Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones, in Annals of botany
, 110(3), 615-627.
(2012), Increased phenotypic plasticity to climate may have boosted the invasion success of polyploid Centaurea stoebe, in PloS one
, 7(11), e50284-e50284.
(2012), Increased population growth rate in invasive polyploid Centaurea stoebe in a common garden, in Ecology letters
, 15(9), 947-954.
(2012), Influence of plant phenostage and ploidy level on oviposition and feeding of two specialist herbivores of spotted knapweed, Centaurea stoebe, in Biological Control
, 60(2), 148-153.
(2011), Competition between cytotypes changes across a longitudinal gradient in Centaurea stoebe (Asteraceae), in American Journal of Botany
, 98(12), 1935-1942.
(2011), Escape from competition: neighbors reduce Centaurea stoebe performance at home but not away, in Ecology
, 92(12), 2208-2213.
(2011), Plant invasions, generalist herbivores, and novel defense weapons, in Ecology
, 92(4), 829-835.
(2011), Polyploidy and invasion success: trait trade-offs in native and introduced cytotypes of two Asteraceae species, in Plant Ecology
, 212(2), 315-325.
(2011), Polyploidy in phenotypic space and invasion context: a morphometric study of Centaurea stoebe sl, in International Journal of Plant Sciences
, 172(3), 386-402.
(2010), Evidence for a combination of pre‐adapted traits and rapid adaptive change in the invasive plant Centaurea stoebe, in Journal of Ecology
, 98(4), 800-813.
(2009), Plant origin and ploidy influence gene expression and life cycle characteristics in an invasive weed, in BMC Plant Biology
, 9(1), 33-33.
(2009), Shift in cytotype frequency and niche space in the invasive plant Centaurea maculosa, in Ecology
, 90(5), 1366-1377.
, Contrasting spatio-temporal climatic niche dynamics during the eastern and western invasions of spotted knapweed in North America, in Journal of Biogeography
Biological invasions are recognized as a major component of global change, with profound effects on ecosystem functioning, biodiversity, health and economics. Why human introductions of some species result in increased abundance and competitiveness has turned out to be one of the greatest challenges to ecologists and evolutionary biologists. Many hypotheses have been put forward to explain plant invasions, including the role of herbivore escape and polyploidy.The proposed project will be the first one that considers the importance of polyploidy and herbivores for invasions simultaneously. Our leading hypothesis is that herbivore pressure and assemblage will, at least partially, explain the predominance of specific cytotypes both in the native and introduced range.The Centaurea stoebe L. (syn. C. maculosa Lam.) (Asteraceae) system provides an excellent model system to study these interactions, and we take advantage of the large knowledge already available on this plant and its herbivores. Native to Europe (EU) where it occurs as a diploid (2x) and a tetraploid (4x) cytotype, the species is highly invasive in North America (NA), where nearly exclusively only 4x plants have been found. Several specialist insect herbivores have been introduced to NA for its biological control, with only partial success so far. In a first part, we will conduct a European-wide survey to explore whether the level of herbivory differs between native populations of the two cytotypes, as well as between experimental transplants of the two cytotypes, and if this leads to differential fitness impact. In a second part, we will conduct a series of experiments to analyse interactions between two selected specialist herbivores that have been introduced as biocontrol agents more than 20 years ago, and the three geocytotypes of C. stoebe (EU 2x, EU 4x and NA 4x). For this, we will grow a large set of populations from both the native and introduced range, with known genetic background and cytotype. We will study oviposition and feeding preference, insect performance and host impact, as well as the population dynamics of the geocytotypes in the presence and absence of these herbivores. Furthermore, we will test, whether these herbivores have undergone evolutionary changes in host selection and performance in the new range. In the third part, we will investigate into the role of generalist herbivores for plant invasions. Firstly, we will assess feeding preference of generalist herbivores on seedlings of the three geocytoypes of C. stoebe. Secondly, we will test, whether exotic species experience a generally reduced attack rate by native generalists as compared to native species, and polyploids as compared to diploids. We will select five groups of four taxonomically closely related species within the Asteraceae. Each group will contain a diploid and polyploidy species that is native, and a diploid and polyploidy species exotic to Europe. Conducting parallel experiments in Europe and North America and testing the same plant species as in Europe, but in different roles (as natives/exotics) will allow us to further test the hypothesis that evolutionarily naïve generalists do less well on a specific introduced exotic species than generalists that have evolved tolerance against the same plant species in their communities of origin.Plant invasions offer great natural experiments to investigate rapid ecological and evolutionary change and to gain insight into factors that regulate the distribution and abundance of organisms. The proposed studies should allow us to draw some generalizations on the relative importance of herbivores as a potential key driver or facilitators for the invasion success of polyploid plants. By looking at mechanisms underlying the invasion success of some of the most prominent plant invaders in Europe and North America, and by conducting studies in both ranges, we will also contribute to the further development of potential control measures, especially for biological control using insect herbivores.