Towards a mechanistic understanding of rapid evolution: An interdisciplinary project to disentangle sources of among-population variation in competitive ability.

• Applicant: Dr. Christoph Rosche
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 451876314

Scope: Rapid evolution is a common occurrence in biological invasions. For example, many common garden experiments report that non-native populations show higher competitive ability than native populations. However, our understanding of rapid evolution is limited because most studies underestimate among-population variation (APV) within and between native and non-native ranges. More specifically, only few studies on rapid evolution disentangle how population histories drive APV. Furthermore, interdisciplinary frameworks of APV-focused research are lacking but could identify mechanisms of rapid evolution, particularly with a view on eco-metabolomics and belowground biotic interactions. We propose addressing rapid evolution of the competitive ability of Conyza canadensis, a species that is well known for its capacity to rapidly respond to environmental changes. Our previous research indicates that C. canadensis experiences large differences for competitive interactions and plant-soil fungal interactions between its native vs. non-native ranges. We also found that APV in plant performance is significantly associated with drought gradients.Methods: We will perform a greenhouse experiment with 162 seed families from 27 native and 27 non-native populations in a competition × drought treatment combination. The samples will be analyzed across three integrative work packages in a coherent manner.WP1: We will assess phenotypic performance to study APV in competitive ability under drought and non-drought conditions. WP2: We will analyze APV in root exudate profiles (mass spectrometry analyses) and APV in allelopathic effects (phytometer analyses). WP3: We will record several root traits and perform amplicon sequencing of root-colonizing fungi to study APV in root-fungal interactions.Overall aims: (1) Testing for rapid evolution in phenotypic competitive ability, drought responses, root exudate profiles, allelopathic activity, resource acquisition patterns and defense mechanisms against fungal pathogens. (2) Improving our knowledge on how belowground mechanisms determine APV in competitive ability by studying the interdependencies of the investigated APVs across our interdisciplinary WPs. Strengths of the study: Our statistical models will disentangle how population histories drive rapid evolution using available field data for competitive regimes, climatic conditions and the soil fungal community. Our ability to do so will be improved by accounting for confounding effects from non-adaptive evolution, spatial autocorrelation, maternal effects and breeding background. We will study APV in research areas where this has received little attention so far (WP2 & WP3). Our multi-tiered approaches are thus anticipated to open novel ways for understanding eco-evolutionary principles and complex interactions between plants, their neighbors and soil fungi. Intense interdisciplinary collaborations will promote project success and stimulate future research.

• DFG Programme: Research Grants