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AraPop – Our interdisciplinary research approach

Detective work: Looking for Arabidopsis thaliana seedlings on a green space in Cologne, Germany (early March 2017)

Our team

To understand the molecular underpinning of natural variation in urban Arabidopsis thaliana populations, functional plant ecologists (AG Linstädter), evolutionary geneticists (AG de Meaux) and molecular geneticist Andrea Schrader (independent researcher with Prof. Hülskamp) have joint forces.

Our study species

Arabidopsis thaliana is a small, annual mustard plant occurring in ruderal habitats. It has an almost worldwide distribution, a very short generation cycle (6-8 weeks) and a tiny genome. These characteristics have made A. thaliana a popular model plant for genetic and physiological studies. Study plants are typically grown under controlled conditions, such as in climate chambers, greenhouses or field experiments. A. thaliana has the potential to become a model plant for linking questions of functional ecology to questions of functional genomics. To this end, we take advantage of the fact that isolated populations of A. thaliana can be found on our doorsteps, i.e. in urban habitats.

Our key questions

1. How do the specific environmental conditions of urban habitats influence the demography, phenology and ecological performance of A. thaliana populations?

2. Is it more phenotypic plasticity or genetic variation that is responsible for A. thaliana’s local adaptation to real-world habitat conditions?

3. Which genetic and ecological mechanisms underpin local adaptation to urban habitats with their different levels of stress, disturbance and competition?

Our methods

Assessing plant demography, phenology and ecological performance
Using methods of population ecology and functional plant ecology, we currently study eight urban populations within the surroundings of Cologne’s Cluster of Excellence on Plant Sciences (CEPLAS) location. At each site we have established at least ten permanent observation plots. During the growth period, key phenological traits (e.g. time of bolting) of marked A. thaliana plants are recorded during regular visits. Evidence of disturbance (e.g. trampling and herbivory), and demographical parameters are recorded as well. Once per year, plant community composition is assessed.

Disentangling phenotypic plasticity and genetic variation
Here we compare phenological and functional traits of Arabidopsis plants grown under natural and controlled conditions. Data are recorded for plants that are either grown under fully controlled conditions (growth chamber), under conditions of shared environmental variation (common garden experiment) or under the natural environmental conditions of the respective urban habitat. The genetic analysis of our populations is currently in progress.

Location of the eight urban A. thaliana populations in south-western Cologne (Germany) currently studied within the AraPop project