Format: ORAL

Anastasia Stefanaki1,2,3*, Floris C. Breman2, Freek T. Bakker2, Robin van Velzen2, M. Eric Schranz2, Tinde van Andel2,3

1 Utrecht University Botanic Gardens, Utrecht, The Netherlands 2 Wageningen University, Wageningen, The Netherlands 3 Naturalis Biodiversity Center, Leiden, The Netherlands * a.stefanaki@uu.nl

Tulipa sylvestris is a small yellow tulip that was introduced in northern Europe during the 16th century by botanists. Unlike commercial ornamental tulips that came from Ottoman gardens, T. sylvestris came from the Mediterranean region. It subsequently escaped from gardens to become widely naturalized in Europe, where it is commonly known as the wild tulip. Its introduction path is poorly understood and complex due to naturalization, polyploidization and a complex taxonomy. We combined historical research and population genomics to reconstruct the introduction history of T. sylvestris in Europe. Our historical search was restricted to original 16th-century sources, including herbarium specimens, botanical texts, illustrations and archives. We also performed genomic repeat profiling, and constructed median networks using rDNA and complete chloroplast genomes. DNA was sampled from native and naturalized T. sylvestris populations across Europe and historic herbarium material, including a 16th-century specimen from the Rauwolf herbarium collected in 1563. Our results show that the introduction of T. syvlestris was not a one-time event but happened through several routes in the period between ca. 1550 and 1580. Famous 16th-century botanists were involved, including Conrad Gessner, Ulisse Aldrovandi, Matthias de Lobel and Carolus Clusius. Seeds were introduced first from the garden of Padova in northern Italy to Zurich, Switzerland, in ca. 15541559. This material was most likely not further spread in Europe. Historical and DNA data point out that naturalized T. sylvestris in northern Europe originates from Bologna in northern Italy. Another introduction route via the west Mediterranean is historically connected with Montpellier in southern France. Our findings show that (ancient) DNA is of great value to fill gaps in historical sources. Moreover, we argue that a genetic approach on past crop movements can only reach its full potential when embedded in proper historical context.