Format: ORAL

Yannick Woudstra1,2,3, Ron Kraaiveld1,4, Alger Jorritsma1, Ernest Rouaud5, Timo van Galen2, Kitty Vijverberg2, Slavica Ivanovic1, Niels C.A.M. Wagemaker4, Roy Erkens5, Heidrun Huber4, Tanja Slotte3, Barbara Gravendeel2,4, Koen J.F. Verhoeven1

1 Netherlands Institute of Ecology, Department of Terrestrial Ecology, Wageningen, The Netherlands 2 Naturalis Biodiversity Center, Ecology & Evolution Group, Leiden, The Netherlands 3 Stockholm University, Department of Ecology, Environment and Plant Science, Stockholm, Sweden 4 Radboud University Nijmegen, Radboud Institute for Biological & Environmental Sciences, Nijmegen, The Netherlands 5 Maastricht University, Maastricht Science Programme, Maastricht, The Netherlands

Urbanisation is a globally increasing and highly impactful form of land-use change. Increased temperatures (the urban heat island effect), habitat fragmentation, light pollution, and other human-induced pressures demand rapid biological adaptation from wild species. To discover the necessary adaptations for surviving urbanisation, we looked at a thriving urban plant species: the common dandelion (Taraxacum officinale F.H.Wigg. s.l.). Along urban-rural transects, we found urban plants to be superior in seedling growth at higher temperatures and flowering response at shorter vernalisation exposure. We also found advancements in flowering time for suburban genotypes, both in the field and in controlled environments. These trends were reflected in sequence divergence patterns for genes involved in the regulation of flowering time and heat resistance, where urban plants displayed highly conserved genotypes. Effects were significantly different between urban habitats, where city park plants presented phenotypes intermediate of urban street and rural field populations. Genetic diversity among individuals was lowest for street plants and highest for rural field plants, likely caused by environmental filtering of genotypes in urban environments. In present-day urban environments, the predicted effects of climate change are already normalised, making cities ideal experimental gardens for studying the necessary biological adaptations. Our approach to study relevant traits in urban plant species from both a phenotypic and genomic point of view is therefore a relevant framework to study the effects of climate change on plant evolution.