THE STUDY SPECIES
Conyza canadensis
Conyza canadensis is an annual weed with a very high individual seed production, pronounced drought tolerance and high plasticity. These traits make this species a successful invader and an economically significant agricultural weed, and as such, an important model species for both invasion biology and weed science. The species is native to North America and non-native to large parts of the rest of the temperate and subtropical world. This cosmopolitan distribution allows studying among-population variation in biotic interactions across large climatic gradients.
C. canadensis has a high capability for rapid evolution given by that it was the first eudicot that evolved glyphosate resistance. This capability for rapid evolution may be promoted by the genome architecture of C. canadensis.
THE MAIN PROJECT
Research scope: Identifying drivers of among-population variation (APV)
Contemporary 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 contemporary evolution is limited because most studies underestimate among-population variation (APV) within and between native and non-native ranges. More specifically, only a few studies on contemporary evolution disentangle how population histories drive APV. Furthermore, integrative frameworks of APV-focused research are lacking but could identify mechanisms of contemporary evolution, particularly with a view on state-of-the-art population genomics, ecometabolomics, and belowground biotic interactions.
Methods
We will perform a greenhouse experiment with 600 seed families from 100 native and 100 non-native populations in a competition × drought treatment combination. For the populations, we will have field data as proxy for population history in terms of competitive regime (i.e., plot biomass), drought regime (i.e., aridity index) and fungal interactions in the rhizosphere (i.e., mutualist-pathogen-ratio). The samples will be analyzed across four integrative work packages (WPs) 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.
WP4: We will genotype the seed families using ddRADseq.
Overall Aims
(1) Principles of rapid evolution:
Investigating how population history determines APV under common garden conditions for competitive ability, drought responses, root exudate profiles, allelopathic activity, resource acquisition patterns and defense mechanisms against fungal pathogens.
(2) Functioning of competitive ability:
Studying correlations between the investigated APVs (i.e., across our interdisciplinary WPs) to unravel how belowground mechanisms determine competitive ability, including genome-wide association studies to identify genomic regions that drive APV in competitive ability.
Add-on studies
We are open for collaborative research on among-population variation in the particular research field of the collaborators´ expertise. We are happy to provide seeds from our samplings and to share information on population history (e.g., field data on drought regime, competitive interactions, soil properties and belowground interactions), ongoing experimental data (e.g., data from the main experiment) and genomic data for the populations. Upcoming and ongoing add-on studies include:
APV in drought responses across four life stages
APV in absolute genome size
APV in plant-herbivore interactions