Fitness consequences of trait-mediated interactions between the invasive plant Impatiens glandulifera, native plants and their pollinators

• Applicants: Professor Dr. Ingo Grass; Dr. Mialy Razanajatovo; Professor Dr. Philipp Schlüter; Privatdozentin Dr. Christine Sabine Sheppard
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 535474543

The proposed project forms aims to narrow the gap between theoretical and empirical research on the effect of biotic interactions on biodiversity dynamics. In this empirical project, we focus on the fitness consequences of interactions between plants and their pollinators. Plant-pollinator interactions can be strongly altered by the arrival of a new dominant species such as an invasive plant. So far, little is known about the impact of invasive plants on pollinator fitness. Moreover, there are conflicting results on how pollinators mediate interactions between invasive and native plants. These pollinator-mediated interactions can either be negative if invaders compete for pollinators or positive if native plants benefit from the spill-over of pollinators attracted to invaders. In this project we aim to reconcile these seemingly conflicting findings by analyzing how traits determine fitness consequences for invasive plants, native plants and pollinators. To this end, we will investigate how intra- and interspecific variation in plant and pollinator traits determine interactions between the invasive plant Impatiens glandulifera, native plant species and the pollinator community. We hypothesize that fitness effects of I. glandulifera on native plants and pollinators range from negative to positive depending on the traits of native plants and pollinators. Our research approach includes experimental measurements of fitness landscapes hypothesized to be shaped by plant-pollinator trait matching and alien-native plant trait similarity. These are complemented by field studies of plant-pollinator communities under natural conditions, investigating interaction networks in landscapes with high vs. Low pollinator diversity. The project mainly focuses on fitness consequences of interspecific trait variation but will complement this by testing for adaptive intraspecific trait differentiation in I. glandulifera. The results from our empirical project will allow us to understand the mechanisms and predict the fitness consequences of the impact of an invasive plant on native plants and pollinators, contributing to the synthesis of the fitness landscapes of the different interaction types studied in FLINT. Extending the concept of fitness landscapes to biotic interactions will enable FLINT to advance theory on the eco-evolutionary dynamics of interaction networks and to synthesize empirical studies on the ecology and evolution of biotic interactions.

• DFG Programme: Research Grants