Humans have spread plants globally for millennia, inadvertently causing ecological disruptions. Apart from their negative effects, biological invasions provide a unique opportunity to study how species modify their niche when confronted with novel environments. Focusing on the Mediterranean Basin, we assessed (1) which traits influence niche dynamics, and (2) whether niche conservatism or niche shift promotes invasion success. We selected the 80 most widespread alien vascular plant species in Mediterranean Europe and compiled data on their distributions in their native and invaded ranges. We then tested how a species' residence time, biogeographic origin, dispersal ability, functional traits, and intraspecific trait variability (ITV) influence its niche dynamics following invasion. Using already published independent data, we finally assessed whether niche dynamics can explain different dimensions of invasion success (quantified as regional spread or local abundance). We found that niche shifts were common (71% of species) and were mostly driven by species failing to occupy all suitable environments in their invaded range (unfilling), regardless of residence time. Niche unfilling and niche expansion were more important in species with high intraspecific trait variability introduced from non-Mediterranean biomes (temperate or tropical). Niche expansion was also greater in species with long-distance dispersal, a narrow native niche, and bigger seeds. Interestingly, invasion success correlated more with a species' ability to conserve its niche and residence time than with niche expansion. Niche shifts were better predicted by species traits than residence time. For example, high adaptive and acclimatization potential (inferred from high intraspecific trait variability) favored niche shifts in general, and long-distance dispersal favored niche expansion. Understanding how these traits relate to niche dynamics is important since a species' ability to conserve and fill its niche is, in turn, a good predictor of invasion success.

• Keywords
• acclimatization, invasion success, invasive species, niche dynamics, niche filling, phenotypic plasticity, rapid adaptation, species traits,
• MeSH
• Plant Dispersal * MeSH
• Ecosystem * MeSH
• Plants * classification   MeSH
• Introduced Species * MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Europe MeSH
• Mediterranean Region MeSH

In a globalized world, plant invasions are common challenges for native ecosystems. Although a considerable number of invasive plants form arbuscular mycorrhizae, interactions between arbuscular mycorrhizal (AM) fungi and invasive and native plants are not well understood. In this study, we conducted a greenhouse experiment examining how AM fungi affect interactions of co-occurring plant species in the family Asteracea, invasive Echinops sphaerocephalus and native forb of central Europe Inula conyzae. The effects of initial soil disturbance, including the effect of intact or disturbed arbuscular mycorrhizal networks (CMNs), were examined. AM fungi supported the success of invasive E. sphaerocephalus in competition with native I. conyzae, regardless of the initial disturbance of CMNs. The presence of invasive E. sphaerocephalus decreased mycorrhizal colonization in I. conyzae, with a concomitant loss in mycorrhizal benefits. Our results confirm AM fungi represent one important mechanism of plant invasion for E. sphaerocephalus in semi-natural European grasslands.

• MeSH
• Echinops Plant microbiology   physiology   MeSH
• Glomeromycota physiology   MeSH
• Inula microbiology   physiology   MeSH
• Mycorrhizae physiology   MeSH
• Grassland MeSH
• Soil Microbiology MeSH
• Introduced Species * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Europe MeSH